Merge tag 'v1.9.1' into parse-bytecode

Fixes for stmhal USB mass storage, lwIP bindings and VFS regressions

This release provides an important fix for the USB mass storage device in
the stmhal port by implementing the SCSI SYNCHRONIZE_CACHE command, which
is now require by some Operating Systems.  There are also fixes for the
lwIP bindings to improve non-blocking sockets and error codes.  The VFS has
some regressions fixed including the ability to statvfs the root.

All changes are listed below.

py core:
- modbuiltins: add core-provided version of input() function
- objstr: catch case of negative "maxsplit" arg to str.rsplit()
- persistentcode: allow to compile with complex numbers disabled
- objstr: allow to compile with obj-repr D, and unicode disabled
- modsys: allow to compile with obj-repr D and PY_ATTRTUPLE disabled
- provide mp_decode_uint_skip() to help reduce stack usage
- makeqstrdefs.py: make script run correctly with Python 2.6
- objstringio: if created from immutable object, follow copy on write policy

extmod:
- modlwip: connect: for non-blocking mode, return EINPROGRESS
- modlwip: fix error codes for duplicate calls to connect()
- modlwip: accept: fix error code for non-blocking mode
- vfs: allow to statvfs the root directory
- vfs: allow "buffering" and "encoding" args to VFS's open()
- modframebuf: fix signed/unsigned comparison pendantic warning

lib:
- libm: use isfinite instead of finitef, for C99 compatibility
- utils/interrupt_char: remove support for KBD_EXCEPTION disabled

tests:
- basics/string_rsplit: add tests for negative "maxsplit" argument
- float: convert "sys.exit()" to "raise SystemExit"
- float/builtin_float_minmax: PEP8 fixes
- basics: convert "sys.exit()" to "raise SystemExit"
- convert remaining "sys.exit()" to "raise SystemExit"

unix port:
- convert to use core-provided version of built-in import()
- Makefile: replace references to make with $(MAKE)

windows port:
- convert to use core-provided version of built-in import()

qemu-arm port:
- Makefile: adjust object-file lists to get correct dependencies
- enable micropython.mem_*() functions to allow more tests

stmhal port:
- boards: enable DAC for NUCLEO_F767ZI board
- add support for NUCLEO_F446RE board
- pass USB handler as parameter to allow more than one USB handler
- usb: use local USB handler variable in Start-of-Frame handler
- usb: make state for USB device private to top-level USB driver
- usbdev: for MSC implement SCSI SYNCHRONIZE_CACHE command
- convert from using stmhal's input() to core provided version

cc3200 port:
- convert from using stmhal's input() to core provided version

teensy port:
- convert from using stmhal's input() to core provided version

esp8266 port:
- Makefile: replace references to make with $(MAKE)
- Makefile: add clean-modules target
- convert from using stmhal's input() to core provided version

zephyr port:
- modusocket: getaddrinfo: Fix mp_obj_len() usage
- define MICROPY_PY_SYS_PLATFORM (to "zephyr")
- machine_pin: use native Zephyr types for Zephyr API calls

docs:
- machine.Pin: remove out_value() method
- machine.Pin: add on() and off() methods
- esp8266: consistently replace Pin.high/low methods with .on/off
- esp8266/quickref: polish Pin.on()/off() examples
- network: move confusingly-named cc3200 Server class to its reference
- uos: deconditionalize, remove minor port-specific details
- uos: move cc3200 port legacy VFS mounting functions to its ref doc
- machine: sort machine classes in logical order, not alphabetically
- network: first step to describe standard network class interface

examples:
- embedding: use core-provided KeyboardInterrupt object

178 files changed, 266 insertions, 374 deletions

diff --git a/tests/basics/array1.py b/tests/basics/array1.py
index 43f775b79..bad879035 100644
--- a/tests/basics/array1.py
+++ b/tests/basics/array1.py
@@ -1,9 +1,8 @@
 try:
     import array
 except ImportError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 a = array.array('B', [1, 2, 3])
 print(a, len(a))
diff --git a/tests/basics/array_add.py b/tests/basics/array_add.py
index 41cd77b42..76ce59f76 100644
--- a/tests/basics/array_add.py
+++ b/tests/basics/array_add.py
@@ -2,9 +2,8 @@
 try:
     import array
 except ImportError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 a1 = array.array('I', [1])
 a2 = array.array('I', [2])
diff --git a/tests/basics/array_construct.py b/tests/basics/array_construct.py
index cafa57784..2221de990 100644
--- a/tests/basics/array_construct.py
+++ b/tests/basics/array_construct.py
@@ -3,9 +3,8 @@
 try:
     from array import array
 except ImportError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 # tuple, list
 print(array('b', (1, 2)))
diff --git a/tests/basics/array_construct2.py b/tests/basics/array_construct2.py
index d1c1a6c70..c305b7f01 100644
--- a/tests/basics/array_construct2.py
+++ b/tests/basics/array_construct2.py
@@ -1,9 +1,8 @@
 try:
     from array import array
 except ImportError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 # construct from something with unknown length (requires generators)
 print(array('i', (i for i in range(10))))
diff --git a/tests/basics/array_construct_endian.py b/tests/basics/array_construct_endian.py
index bf34b05d1..990d7b1ea 100644
--- a/tests/basics/array_construct_endian.py
+++ b/tests/basics/array_construct_endian.py
@@ -3,9 +3,8 @@
 try:
     from array import array
 except ImportError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 # raw copy from bytes, bytearray
 print(array('h', b'12'))
diff --git a/tests/basics/array_intbig.py b/tests/basics/array_intbig.py
index 4a3b2a0d4..5702a8ae6 100644
--- a/tests/basics/array_intbig.py
+++ b/tests/basics/array_intbig.py
@@ -3,9 +3,8 @@
 try:
     from array import array
 except ImportError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 print(array('L', [0, 2**32-1]))
 print(array('l', [-2**31, 0, 2**31-1]))
diff --git a/tests/basics/array_micropython.py b/tests/basics/array_micropython.py
index 0c1df0923..e26ad7ae9 100644
--- a/tests/basics/array_micropython.py
+++ b/tests/basics/array_micropython.py
@@ -2,9 +2,8 @@
 try:
     import array
 except ImportError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 # arrays of objects
 a = array.array('O')
diff --git a/tests/basics/attrtuple1.py b/tests/basics/attrtuple1.py
index 597bfc2a3..78a0fbed1 100644
--- a/tests/basics/attrtuple1.py
+++ b/tests/basics/attrtuple1.py
@@ -8,9 +8,8 @@ t = sys.implementation
 try:
     t.name
 except AttributeError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 
 # test printing of attrtuple
diff --git a/tests/basics/builtin_delattr.py b/tests/basics/builtin_delattr.py
index 9b38837e4..65bd0f210 100644
--- a/tests/basics/builtin_delattr.py
+++ b/tests/basics/builtin_delattr.py
@@ -2,9 +2,8 @@
 try:
     delattr
 except:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 class A: pass
 a = A()
diff --git a/tests/basics/builtin_help.py b/tests/basics/builtin_help.py
index d554f308d..6ec39653f 100644
--- a/tests/basics/builtin_help.py
+++ b/tests/basics/builtin_help.py
@@ -4,8 +4,7 @@ try:
     help
 except NameError:
     print("SKIP")
-    import sys
-    sys.exit()
+    raise SystemExit
 
 help() # no args
 help(help) # help for a function
diff --git a/tests/basics/builtin_minmax.py b/tests/basics/builtin_minmax.py
index a925b3fe9..184398e64 100644
--- a/tests/basics/builtin_minmax.py
+++ b/tests/basics/builtin_minmax.py
@@ -3,9 +3,8 @@ try:
     min
     max
 except:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 print(min(0,1))
 print(min(1,0))
diff --git a/tests/basics/builtin_override.py b/tests/basics/builtin_override.py
index f3632e59a..9f91341ed 100644
--- a/tests/basics/builtin_override.py
+++ b/tests/basics/builtin_override.py
@@ -6,9 +6,8 @@ import builtins
 try:
     builtins.abs = lambda x: x + 1
 except AttributeError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 print(abs(1))
 
diff --git a/tests/basics/builtin_pow3.py b/tests/basics/builtin_pow3.py
index dec7253bb..69b57e548 100644
--- a/tests/basics/builtin_pow3.py
+++ b/tests/basics/builtin_pow3.py
@@ -4,9 +4,8 @@
 try:
     print(pow(3, 4, 7))
 except NotImplementedError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 # 3 arg pow is defined to only work on integers
 try:
diff --git a/tests/basics/builtin_pow3_intbig.py b/tests/basics/builtin_pow3_intbig.py
index 9f482cbde..bedc8b36b 100644
--- a/tests/basics/builtin_pow3_intbig.py
+++ b/tests/basics/builtin_pow3_intbig.py
@@ -4,9 +4,8 @@
 try:
     print(pow(3, 4, 7))
 except NotImplementedError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 print(pow(555557, 1000002, 1000003))
 
diff --git a/tests/basics/builtin_property.py b/tests/basics/builtin_property.py
index ff4ff073c..89c3d4936 100644
--- a/tests/basics/builtin_property.py
+++ b/tests/basics/builtin_property.py
@@ -2,9 +2,8 @@
 try:
     property
 except:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 # create a property object explicitly
 property()
diff --git a/tests/basics/builtin_range_attrs.py b/tests/basics/builtin_range_attrs.py
index 9327c802a..05d666d13 100644
--- a/tests/basics/builtin_range_attrs.py
+++ b/tests/basics/builtin_range_attrs.py
@@ -3,9 +3,8 @@
 try:
     range(0).start
 except AttributeError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 # attrs
 print(range(1, 2, 3).start)
diff --git a/tests/basics/builtin_reversed.py b/tests/basics/builtin_reversed.py
index 59e9c7821..f43505a8b 100644
--- a/tests/basics/builtin_reversed.py
+++ b/tests/basics/builtin_reversed.py
@@ -2,9 +2,8 @@
 try:
     reversed
 except:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 # list
 print(list(reversed([])))
diff --git a/tests/basics/builtin_sorted.py b/tests/basics/builtin_sorted.py
index 68855b61b..6435f86d0 100644
--- a/tests/basics/builtin_sorted.py
+++ b/tests/basics/builtin_sorted.py
@@ -3,9 +3,8 @@ try:
     sorted
     set
 except:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 print(sorted(set(range(100))))
 print(sorted(set(range(100)), key=lambda x: x + 100*(x % 2)))
diff --git a/tests/basics/bytearray_construct_array.py b/tests/basics/bytearray_construct_array.py
index 6d45cafda..bde5fa08b 100644
--- a/tests/basics/bytearray_construct_array.py
+++ b/tests/basics/bytearray_construct_array.py
@@ -2,9 +2,8 @@
 try:
     from array import array
 except ImportError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 # arrays
 print(bytearray(array('b', [1, 2])))
diff --git a/tests/basics/bytearray_construct_endian.py b/tests/basics/bytearray_construct_endian.py
index f68f9b89d..0002f19c5 100644
--- a/tests/basics/bytearray_construct_endian.py
+++ b/tests/basics/bytearray_construct_endian.py
@@ -2,9 +2,8 @@
 try:
     from array import array
 except ImportError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 # arrays
 print(bytearray(array('h', [1, 2])))
diff --git a/tests/basics/bytearray_slice_assign.py b/tests/basics/bytearray_slice_assign.py
index c4b5c43e3..48f5938a5 100644
--- a/tests/basics/bytearray_slice_assign.py
+++ b/tests/basics/bytearray_slice_assign.py
@@ -2,8 +2,7 @@ try:
     bytearray()[:] = bytearray()
 except TypeError:
     print("SKIP")
-    import sys
-    sys.exit()
+    raise SystemExit
 
 # test slices; only 2 argument version supported by Micro Python at the moment
 x = bytearray(range(10))
diff --git a/tests/basics/bytes_add_array.py b/tests/basics/bytes_add_array.py
index 2b8cbccef..b17556d83 100644
--- a/tests/basics/bytes_add_array.py
+++ b/tests/basics/bytes_add_array.py
@@ -2,9 +2,8 @@
 try:
     import array
 except ImportError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 # should be byteorder-neutral
 print(b"123" + array.array('h', [0x1515]))
diff --git a/tests/basics/bytes_add_endian.py b/tests/basics/bytes_add_endian.py
index 1bbd0f2c3..8cfffa7b6 100644
--- a/tests/basics/bytes_add_endian.py
+++ b/tests/basics/bytes_add_endian.py
@@ -2,8 +2,7 @@
 try:
     import array
 except ImportError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 print(b"123" + array.array('i', [1]))
diff --git a/tests/basics/bytes_compare_array.py b/tests/basics/bytes_compare_array.py
index ad41d1d37..ad378de70 100644
--- a/tests/basics/bytes_compare_array.py
+++ b/tests/basics/bytes_compare_array.py
@@ -1,9 +1,8 @@
 try:
     import array
 except ImportError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 print(array.array('b', [1, 2]) in b'\x01\x02\x03')
 # CPython gives False here
diff --git a/tests/basics/bytes_construct_array.py b/tests/basics/bytes_construct_array.py
index 72c2d0c58..453eb5901 100644
--- a/tests/basics/bytes_construct_array.py
+++ b/tests/basics/bytes_construct_array.py
@@ -2,9 +2,8 @@
 try:
     from array import array
 except ImportError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 # arrays
 print(bytes(array('b', [1, 2])))
diff --git a/tests/basics/bytes_construct_endian.py b/tests/basics/bytes_construct_endian.py
index 77e0eaaa5..cf1a9f408 100644
--- a/tests/basics/bytes_construct_endian.py
+++ b/tests/basics/bytes_construct_endian.py
@@ -3,9 +3,8 @@
 try:
     from array import array
 except ImportError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 # arrays
 print(bytes(array('h', [1, 2])))
diff --git a/tests/basics/bytes_partition.py b/tests/basics/bytes_partition.py
index 7d3ffaaaa..5b503f544 100644
--- a/tests/basics/bytes_partition.py
+++ b/tests/basics/bytes_partition.py
@@ -2,8 +2,7 @@ try:
     str.partition
 except AttributeError:
     print("SKIP")
-    import sys
-    sys.exit()
+    raise SystemExit
 
 print(b"asdf".partition(b'g'))
 print(b"asdf".partition(b'a'))
diff --git a/tests/basics/class_delattr_setattr.py b/tests/basics/class_delattr_setattr.py
index 0d061aee6..190b4875b 100644
--- a/tests/basics/class_delattr_setattr.py
+++ b/tests/basics/class_delattr_setattr.py
@@ -6,9 +6,8 @@ try:
         def __delattr__(self, attr): pass
     del Test().noexist
 except AttributeError:
-    import sys
     print('SKIP')
-    sys.exit()
+    raise SystemExit
 
 # this class just prints the calls to see if they were executed
 class A():
diff --git a/tests/basics/class_descriptor.py b/tests/basics/class_descriptor.py
index 7f295f071..eb88ba7b9 100644
--- a/tests/basics/class_descriptor.py
+++ b/tests/basics/class_descriptor.py
@@ -21,9 +21,8 @@ m = Main()
 try:
     m.__class__
 except AttributeError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 r = m.Forward
 if 'Descriptor' in repr(r.__class__):
diff --git a/tests/basics/class_new.py b/tests/basics/class_new.py
index 0198456b2..9a7072ad0 100644
--- a/tests/basics/class_new.py
+++ b/tests/basics/class_new.py
@@ -3,9 +3,8 @@ try:
     # nothing to test.
     object.__new__
 except AttributeError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 class A:
     def __new__(cls):
         print("A.__new__")
diff --git a/tests/basics/class_store_class.py b/tests/basics/class_store_class.py
index 00a291586..797f88f85 100644
--- a/tests/basics/class_store_class.py
+++ b/tests/basics/class_store_class.py
@@ -8,9 +8,8 @@ except ImportError:
     try:
         from ucollections import namedtuple
     except ImportError:
-        import sys
         print("SKIP")
-        sys.exit()
+        raise SystemExit
 
 _DefragResultBase = namedtuple('DefragResult', [ 'foo', 'bar' ])
 
diff --git a/tests/basics/class_super_object.py b/tests/basics/class_super_object.py
index a841d34ab..1fddbb38f 100644
--- a/tests/basics/class_super_object.py
+++ b/tests/basics/class_super_object.py
@@ -4,9 +4,8 @@ try:
     # nothing to test.
     object.__init__
 except AttributeError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 class Test(object):
     def __init__(self):
diff --git a/tests/basics/dict_fromkeys2.py b/tests/basics/dict_fromkeys2.py
index 7ea0cc5b3..dce1e8ef5 100644
--- a/tests/basics/dict_fromkeys2.py
+++ b/tests/basics/dict_fromkeys2.py
@@ -1,9 +1,8 @@
 try:
     reversed
 except:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 # argument to fromkeys has no __len__
 d = dict.fromkeys(reversed(range(1)))
diff --git a/tests/basics/enumerate.py b/tests/basics/enumerate.py
index 3cc1350a0..4f8239bf7 100644
--- a/tests/basics/enumerate.py
+++ b/tests/basics/enumerate.py
@@ -1,9 +1,8 @@
 try:
     enumerate
 except:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 print(list(enumerate([])))
 print(list(enumerate([1, 2, 3])))
diff --git a/tests/basics/errno1.py b/tests/basics/errno1.py
index eae1bbe1b..63930b767 100644
--- a/tests/basics/errno1.py
+++ b/tests/basics/errno1.py
@@ -4,8 +4,7 @@ try:
     import uerrno
 except ImportError:
     print("SKIP")
-    import sys
-    sys.exit()
+    raise SystemExit
 
 # check that constants exist and are integers
 print(type(uerrno.EIO))
diff --git a/tests/basics/filter.py b/tests/basics/filter.py
index d0b36733c..c6d97cf9b 100644
--- a/tests/basics/filter.py
+++ b/tests/basics/filter.py
@@ -1,9 +1,8 @@
 try:
     filter
 except:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 print(list(filter(lambda x: x & 1, range(-3, 4))))
 print(list(filter(None, range(-3, 4))))
diff --git a/tests/basics/frozenset1.py b/tests/basics/frozenset1.py
index 7a4a33540..7bec24c29 100644
--- a/tests/basics/frozenset1.py
+++ b/tests/basics/frozenset1.py
@@ -4,8 +4,7 @@ try:
     frozenset
 except NameError:
     print("SKIP")
-    import sys
-    sys.exit()
+    raise SystemExit
 
 s = frozenset()
 print(s)
diff --git a/tests/basics/frozenset_add.py b/tests/basics/frozenset_add.py
index 415a8c2e1..fe24fbaf1 100644
--- a/tests/basics/frozenset_add.py
+++ b/tests/basics/frozenset_add.py
@@ -2,8 +2,7 @@ try:
     frozenset
 except NameError:
     print("SKIP")
-    import sys
-    sys.exit()
+    raise SystemExit
 
 s = frozenset({1, 2, 3, 4})
 try:
diff --git a/tests/basics/frozenset_binop.py b/tests/basics/frozenset_binop.py
index 5cc07e9e1..61af07a23 100644
--- a/tests/basics/frozenset_binop.py
+++ b/tests/basics/frozenset_binop.py
@@ -2,8 +2,7 @@ try:
     frozenset
 except NameError:
     print("SKIP")
-    import sys
-    sys.exit()
+    raise SystemExit
 
 sets = [
     frozenset(), frozenset({1}), frozenset({1, 2}), frozenset({1, 2, 3}), frozenset({2, 3}),
diff --git a/tests/basics/frozenset_copy.py b/tests/basics/frozenset_copy.py
index 92e115d34..c90f541a1 100644
--- a/tests/basics/frozenset_copy.py
+++ b/tests/basics/frozenset_copy.py
@@ -2,8 +2,7 @@ try:
     frozenset
 except NameError:
     print("SKIP")
-    import sys
-    sys.exit()
+    raise SystemExit
 
 s = frozenset({1, 2, 3, 4})
 t = s.copy()
diff --git a/tests/basics/frozenset_difference.py b/tests/basics/frozenset_difference.py
index 3d142f959..bc8b9c21c 100644
--- a/tests/basics/frozenset_difference.py
+++ b/tests/basics/frozenset_difference.py
@@ -2,8 +2,7 @@ try:
     frozenset
 except NameError:
     print("SKIP")
-    import sys
-    sys.exit()
+    raise SystemExit
 
 l = [1, 2, 3, 4]
 s = frozenset(l)
diff --git a/tests/basics/frozenset_set.py b/tests/basics/frozenset_set.py
index b334694b5..3bf456acf 100644
--- a/tests/basics/frozenset_set.py
+++ b/tests/basics/frozenset_set.py
@@ -2,8 +2,7 @@ try:
     frozenset
 except NameError:
     print("SKIP")
-    import sys
-    sys.exit()
+    raise SystemExit
 
 # Examples from https://docs.python.org/3/library/stdtypes.html#set
 # "Instances of set are compared to instances of frozenset based on their
diff --git a/tests/basics/fun_error2.py b/tests/basics/fun_error2.py
index c4d2c0b64..2a00396e6 100644
--- a/tests/basics/fun_error2.py
+++ b/tests/basics/fun_error2.py
@@ -3,8 +3,7 @@ try:
     enumerate
 except:
     print("SKIP")
-    import sys
-    sys.exit()
+    raise SystemExit
 
 def test_exc(code, exc):
     try:
diff --git a/tests/basics/gc1.py b/tests/basics/gc1.py
index be6c6faed..dcbe0bfcf 100644
--- a/tests/basics/gc1.py
+++ b/tests/basics/gc1.py
@@ -4,8 +4,7 @@ try:
     import gc
 except ImportError:
     print("SKIP")
-    import sys
-    sys.exit()
+    raise SystemExit
 
 print(gc.isenabled())
 gc.disable()
diff --git a/tests/basics/memoryview1.py b/tests/basics/memoryview1.py
index a771acdda..c4cc6ffab 100644
--- a/tests/basics/memoryview1.py
+++ b/tests/basics/memoryview1.py
@@ -2,9 +2,8 @@
 try:
     memoryview
 except:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 # test reading from bytes
 b = b'1234'
diff --git a/tests/basics/memoryview2.py b/tests/basics/memoryview2.py
index 4b5af852b..06a7be59f 100644
--- a/tests/basics/memoryview2.py
+++ b/tests/basics/memoryview2.py
@@ -3,9 +3,8 @@ try:
     from array import array
     memoryview
 except:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 print(list(memoryview(b'\x7f\x80\x81\xff')))
 print(list(memoryview(array('b', [0x7f, -0x80]))))
diff --git a/tests/basics/memoryview_gc.py b/tests/basics/memoryview_gc.py
index 9d4857e36..d366cbbb1 100644
--- a/tests/basics/memoryview_gc.py
+++ b/tests/basics/memoryview_gc.py
@@ -2,9 +2,8 @@
 try:
     memoryview
 except:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 b = bytearray(10)
 m = memoryview(b)[1:]
diff --git a/tests/basics/memoryview_intbig.py b/tests/basics/memoryview_intbig.py
index 180f15d18..a76d9cbec 100644
--- a/tests/basics/memoryview_intbig.py
+++ b/tests/basics/memoryview_intbig.py
@@ -3,9 +3,8 @@ try:
     from array import array
     memoryview
 except:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 print(list(memoryview(array('i', [0x7f000000, -0x80000000]))))
 print(list(memoryview(array('I', [0x7f000000, 0x80000000, 0x81000000, 0xffffffff]))))
diff --git a/tests/basics/namedtuple1.py b/tests/basics/namedtuple1.py
index 132dcf96b..b9a007240 100644
--- a/tests/basics/namedtuple1.py
+++ b/tests/basics/namedtuple1.py
@@ -4,9 +4,8 @@ try:
     except ImportError:
         from ucollections import namedtuple
 except ImportError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 T = namedtuple("Tup", ["foo", "bar"])
 # CPython prints fully qualified name, what we don't bother to do so far
@@ -76,7 +75,7 @@ T4 = namedtuple("TupTuple", ("foo", "bar"))
 t = T4(1, 2)
 print(t.foo, t.bar)
 
-# Try single string with comma field seperator
+# Try single string with comma field separator
 # Not implemented so far
 #T2 = namedtuple("TupComma", "foo,bar")
 #t = T2(1, 2)
diff --git a/tests/basics/object_dict.py b/tests/basics/object_dict.py
index e6fb7b3d9..7bf7094e3 100644
--- a/tests/basics/object_dict.py
+++ b/tests/basics/object_dict.py
@@ -1,4 +1,3 @@
-import sys
 
 class Foo:
 
@@ -9,6 +8,6 @@ class Foo:
 o = Foo()
 if not hasattr(o, "__dict__"):
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 print(o.__dict__ == {'a': 1, 'b': 'bar'})
diff --git a/tests/basics/object_new.py b/tests/basics/object_new.py
index 568feccda..a9c9482cb 100644
--- a/tests/basics/object_new.py
+++ b/tests/basics/object_new.py
@@ -7,9 +7,8 @@ try:
     # nothing to test.
     object.__new__
 except AttributeError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 class Foo:
 
diff --git a/tests/basics/op_error_memoryview.py b/tests/basics/op_error_memoryview.py
index 658ededc8..8d4403f77 100644
--- a/tests/basics/op_error_memoryview.py
+++ b/tests/basics/op_error_memoryview.py
@@ -2,9 +2,8 @@
 try:
     memoryview
 except:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 def test_exc(code, exc):
     try:
diff --git a/tests/basics/ordereddict1.py b/tests/basics/ordereddict1.py
index 7147968c5..d1633f0bb 100644
--- a/tests/basics/ordereddict1.py
+++ b/tests/basics/ordereddict1.py
@@ -5,8 +5,7 @@ except ImportError:
         from ucollections import OrderedDict
     except ImportError:
         print("SKIP")
-        import sys
-        sys.exit()
+        raise SystemExit
 
 d = OrderedDict([(10, 20), ("b", 100), (1, 2)])
 print(len(d))
diff --git a/tests/basics/ordereddict_eq.py b/tests/basics/ordereddict_eq.py
index 274660877..c69daf880 100644
--- a/tests/basics/ordereddict_eq.py
+++ b/tests/basics/ordereddict_eq.py
@@ -5,8 +5,7 @@ except ImportError:
         from ucollections import OrderedDict
     except ImportError:
         print("SKIP")
-        import sys
-        sys.exit()
+        raise SystemExit
 
 x = OrderedDict()
 y = OrderedDict()
diff --git a/tests/basics/parser.py b/tests/basics/parser.py
index 8fb2a49bf..626b67ad7 100644
--- a/tests/basics/parser.py
+++ b/tests/basics/parser.py
@@ -4,8 +4,7 @@ try:
     compile
 except NameError:
     print("SKIP")
-    import sys
-    sys.exit()
+    raise SystemExit
 
 # completely empty string
 # uPy and CPy differ for this case
diff --git a/tests/basics/set_type.py b/tests/basics/set_type.py
index d790fa062..787a99e81 100644
--- a/tests/basics/set_type.py
+++ b/tests/basics/set_type.py
@@ -5,9 +5,8 @@
 try:
     set
 except NameError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 print(set)
 
diff --git a/tests/basics/slice_attrs.py b/tests/basics/slice_attrs.py
index 67456ff8e..e85ead4ba 100644
--- a/tests/basics/slice_attrs.py
+++ b/tests/basics/slice_attrs.py
@@ -8,9 +8,8 @@ class A:
 try:
     t = A()[1:2]
 except:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 
 A()[1:2:3]
diff --git a/tests/basics/special_methods2.py b/tests/basics/special_methods2.py
index 3623b30dc..ba7cf27cd 100644
--- a/tests/basics/special_methods2.py
+++ b/tests/basics/special_methods2.py
@@ -100,9 +100,8 @@ cud2 = Cud()
 try:
     +cud1
 except TypeError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 # the following require MICROPY_PY_ALL_SPECIAL_METHODS
 +cud1
diff --git a/tests/basics/string_center.py b/tests/basics/string_center.py
index a2739201a..40e8af4b8 100644
--- a/tests/basics/string_center.py
+++ b/tests/basics/string_center.py
@@ -1,9 +1,8 @@
 try:
     str.center
 except:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 print("foo".center(0))
 print("foo".center(1))
diff --git a/tests/basics/string_partition.py b/tests/basics/string_partition.py
index b3b2f0907..bc36388fd 100644
--- a/tests/basics/string_partition.py
+++ b/tests/basics/string_partition.py
@@ -2,8 +2,7 @@ try:
     str.partition
 except AttributeError:
     print("SKIP")
-    import sys
-    sys.exit()
+    raise SystemExit
 
 print("asdf".partition('g'))
 print("asdf".partition('a'))
diff --git a/tests/basics/string_rpartition.py b/tests/basics/string_rpartition.py
index 84e0031fb..6d65dfaf2 100644
--- a/tests/basics/string_rpartition.py
+++ b/tests/basics/string_rpartition.py
@@ -2,8 +2,7 @@ try:
     str.partition
 except AttributeError:
     print("SKIP")
-    import sys
-    sys.exit()
+    raise SystemExit
 
 print("asdf".rpartition('g'))
 print("asdf".rpartition('a'))
diff --git a/tests/basics/string_rsplit.py b/tests/basics/string_rsplit.py
index 563b64f1c..b92b8f359 100644
--- a/tests/basics/string_rsplit.py
+++ b/tests/basics/string_rsplit.py
@@ -52,3 +52,7 @@ print("/*10/*11/*12/*".rsplit("/*", 4))
 print("/*10/*11/*12/*".rsplit("/*", 5))
 
 print(b"abcabc".rsplit(b"bc", 2))
+
+# negative "maxsplit" should delegate to .split()
+print('abaca'.rsplit('a', -1))
+print('abaca'.rsplit('a', -2))
diff --git a/tests/basics/string_splitlines.py b/tests/basics/string_splitlines.py
index 1d08f6e6d..c4c3fcb80 100644
--- a/tests/basics/string_splitlines.py
+++ b/tests/basics/string_splitlines.py
@@ -3,9 +3,8 @@
 try:
     str.splitlines
 except:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 # test \n as newline
 print("foo\nbar".splitlines())
diff --git a/tests/basics/struct1.py b/tests/basics/struct1.py
index bb6877c78..a442beb1e 100644
--- a/tests/basics/struct1.py
+++ b/tests/basics/struct1.py
@@ -4,9 +4,8 @@ except:
     try:
         import struct
     except ImportError:
-        import sys
         print("SKIP")
-        sys.exit()
+        raise SystemExit
 
 print(struct.calcsize("<bI"))
 print(struct.unpack("<bI", b"\x80\0\0\x01\0"))
diff --git a/tests/basics/struct1_intbig.py b/tests/basics/struct1_intbig.py
index 7f4c3ce12..b1fec527e 100644
--- a/tests/basics/struct1_intbig.py
+++ b/tests/basics/struct1_intbig.py
@@ -4,9 +4,8 @@ except:
     try:
         import struct
     except ImportError:
-        import sys
         print("SKIP")
-        sys.exit()
+        raise SystemExit
 
 # check maximum pack on 32-bit machine
 print(struct.pack("<I", 2**32 - 1))
diff --git a/tests/basics/struct2.py b/tests/basics/struct2.py
index e3f8bbebf..d8234d0d3 100644
--- a/tests/basics/struct2.py
+++ b/tests/basics/struct2.py
@@ -6,9 +6,8 @@ except:
     try:
         import struct
     except ImportError:
-        import sys
         print("SKIP")
-        sys.exit()
+        raise SystemExit
 
 print(struct.calcsize('0s'))
 print(struct.unpack('0s', b''))
diff --git a/tests/basics/struct_micropython.py b/tests/basics/struct_micropython.py
index 53306dad6..4b9dfe137 100644
--- a/tests/basics/struct_micropython.py
+++ b/tests/basics/struct_micropython.py
@@ -6,9 +6,8 @@ except:
     try:
         import struct
     except ImportError:
-        import sys
         print("SKIP")
-        sys.exit()
+        raise SystemExit
 
 class A():
     pass
diff --git a/tests/basics/subclass_classmethod.py b/tests/basics/subclass_classmethod.py
index 48f164b36..00a2ebd7c 100644
--- a/tests/basics/subclass_classmethod.py
+++ b/tests/basics/subclass_classmethod.py
@@ -8,9 +8,8 @@ class Base:
 try:
     Base.__name__
 except AttributeError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 class Sub(Base):
     pass
diff --git a/tests/basics/sys1.py b/tests/basics/sys1.py
index 29ef974d1..0d74a1292 100644
--- a/tests/basics/sys1.py
+++ b/tests/basics/sys1.py
@@ -20,7 +20,7 @@ except AttributeError:
     print(True)
 
 try:
-    sys.exit()
+    raise SystemExit
 except SystemExit as e:
     print("SystemExit", e.args)
 
diff --git a/tests/basics/try_reraise2.py b/tests/basics/try_reraise2.py
index d9434397c..5648d2467 100644
--- a/tests/basics/try_reraise2.py
+++ b/tests/basics/try_reraise2.py
@@ -1,4 +1,4 @@
-# Reraise not the latest occured exception
+# Reraise not the latest occurred exception
 def f():
     try:
         raise ValueError("val", 3)
diff --git a/tests/basics/zip.py b/tests/basics/zip.py
index 958addb7a..66f2544e5 100644
--- a/tests/basics/zip.py
+++ b/tests/basics/zip.py
@@ -3,8 +3,7 @@ try:
     set
 except NameError:
     print("SKIP")
-    import sys
-    sys.exit()
+    raise SystemExit
 
 print(list(zip()))
 print(list(zip([1], set([2, 3]))))
diff --git a/tests/extmod/btree1.py b/tests/extmod/btree1.py
index 2127554db..59638ef0a 100644
--- a/tests/extmod/btree1.py
+++ b/tests/extmod/btree1.py
@@ -4,8 +4,7 @@ try:
     import uerrno
 except ImportError:
     print("SKIP")
-    import sys
-    sys.exit()
+    raise SystemExit
 
 #f = open("_test.db", "w+b")
 f = uio.BytesIO()
diff --git a/tests/extmod/framebuf1.py b/tests/extmod/framebuf1.py
index 990b0b120..2c1366522 100644
--- a/tests/extmod/framebuf1.py
+++ b/tests/extmod/framebuf1.py
@@ -2,8 +2,7 @@ try:
     import framebuf
 except ImportError:
     print("SKIP")
-    import sys
-    sys.exit()
+    raise SystemExit
 
 w = 5
 h = 16
diff --git a/tests/extmod/framebuf16.py b/tests/extmod/framebuf16.py
index 3aa1d34de..fe81f7f93 100644
--- a/tests/extmod/framebuf16.py
+++ b/tests/extmod/framebuf16.py
@@ -2,8 +2,7 @@ try:
     import framebuf
 except ImportError:
     print("SKIP")
-    import sys
-    sys.exit()
+    raise SystemExit
 
 def printbuf():
     print("--8<--")
diff --git a/tests/extmod/framebuf4.py b/tests/extmod/framebuf4.py
index 641f5bfc5..8358fa55b 100644
--- a/tests/extmod/framebuf4.py
+++ b/tests/extmod/framebuf4.py
@@ -2,8 +2,7 @@ try:
     import framebuf
 except ImportError:
     print("SKIP")
-    import sys
-    sys.exit()
+    raise SystemExit
 
 def printbuf():
     print("--8<--")
diff --git a/tests/extmod/machine1.py b/tests/extmod/machine1.py
index e0c561168..6ff38cc05 100644
--- a/tests/extmod/machine1.py
+++ b/tests/extmod/machine1.py
@@ -8,8 +8,7 @@ try:
     machine.mem8
 except:
     print("SKIP")
-    import sys
-    sys.exit()
+    raise SystemExit
 
 print(machine.mem8)
 
diff --git a/tests/extmod/machine_pinbase.py b/tests/extmod/machine_pinbase.py
index 5e82823ec..e91775504 100644
--- a/tests/extmod/machine_pinbase.py
+++ b/tests/extmod/machine_pinbase.py
@@ -6,8 +6,7 @@ try:
     machine.PinBase
 except AttributeError:
     print("SKIP")
-    import sys
-    sys.exit()
+    raise SystemExit
 
 
 class MyPin(machine.PinBase):
diff --git a/tests/extmod/machine_pulse.py b/tests/extmod/machine_pulse.py
index 6491b5409..d525974e0 100644
--- a/tests/extmod/machine_pulse.py
+++ b/tests/extmod/machine_pulse.py
@@ -7,8 +7,7 @@ try:
     machine.time_pulse_us
 except AttributeError:
     print("SKIP")
-    import sys
-    sys.exit()
+    raise SystemExit
 
 
 class ConstPin(machine.PinBase):
diff --git a/tests/extmod/machine_signal.py b/tests/extmod/machine_signal.py
index 96b8f43c7..53f4f5890 100644
--- a/tests/extmod/machine_signal.py
+++ b/tests/extmod/machine_signal.py
@@ -9,8 +9,7 @@ try:
     machine.Signal
 except AttributeError:
     print("SKIP")
-    import sys
-    sys.exit()
+    raise SystemExit
 
 class Pin(machine.PinBase):
     def __init__(self):
diff --git a/tests/extmod/time_ms_us.py b/tests/extmod/time_ms_us.py
index 2078f1bb5..31f07d31b 100644
--- a/tests/extmod/time_ms_us.py
+++ b/tests/extmod/time_ms_us.py
@@ -1,10 +1,9 @@
-import sys
 import utime
 try:
     utime.sleep_ms
 except AttributeError:
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 utime.sleep_ms(1)
 utime.sleep_us(1)
diff --git a/tests/extmod/ubinascii_a2b_base64.py b/tests/extmod/ubinascii_a2b_base64.py
index 58eb0b50b..b35f26591 100644
--- a/tests/extmod/ubinascii_a2b_base64.py
+++ b/tests/extmod/ubinascii_a2b_base64.py
@@ -4,9 +4,8 @@ try:
     except ImportError:
         import binascii
 except ImportError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 print(binascii.a2b_base64(b''))
 print(binascii.a2b_base64(b'Zg=='))
diff --git a/tests/extmod/ubinascii_b2a_base64.py b/tests/extmod/ubinascii_b2a_base64.py
index 1c0c30311..f4bb69fe0 100644
--- a/tests/extmod/ubinascii_b2a_base64.py
+++ b/tests/extmod/ubinascii_b2a_base64.py
@@ -4,9 +4,8 @@ try:
     except ImportError:
         import binascii
 except ImportError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 print(binascii.b2a_base64(b''))
 print(binascii.b2a_base64(b'f'))
diff --git a/tests/extmod/ubinascii_crc32.py b/tests/extmod/ubinascii_crc32.py
index b82c44d6b..89664a9b3 100644
--- a/tests/extmod/ubinascii_crc32.py
+++ b/tests/extmod/ubinascii_crc32.py
@@ -4,16 +4,14 @@ try:
     except ImportError:
         import binascii
 except ImportError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 try:
     binascii.crc32
 except AttributeError:
     print("SKIP")
-    import sys
-    sys.exit()
+    raise SystemExit
 
 print(hex(binascii.crc32(b'The quick brown fox jumps over the lazy dog')))
 print(hex(binascii.crc32(b'\x00' * 32)))
diff --git a/tests/extmod/ubinascii_hexlify.py b/tests/extmod/ubinascii_hexlify.py
index 5d70bda96..bc9928747 100644
--- a/tests/extmod/ubinascii_hexlify.py
+++ b/tests/extmod/ubinascii_hexlify.py
@@ -4,9 +4,8 @@ try:
     except ImportError:
         import binascii
 except ImportError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 print(binascii.hexlify(b'\x00\x01\x02\x03\x04\x05\x06\x07'))
 print(binascii.hexlify(b'\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f'))
diff --git a/tests/extmod/ubinascii_micropython.py b/tests/extmod/ubinascii_micropython.py
index 96f566bd1..a4c00a2cb 100644
--- a/tests/extmod/ubinascii_micropython.py
+++ b/tests/extmod/ubinascii_micropython.py
@@ -4,9 +4,8 @@ try:
     except ImportError:
         import binascii
 except ImportError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 # two arguments supported in uPy but not CPython
 a = binascii.hexlify(b'123', ':')
diff --git a/tests/extmod/ubinascii_unhexlify.py b/tests/extmod/ubinascii_unhexlify.py
index e669789ba..865abfe3a 100644
--- a/tests/extmod/ubinascii_unhexlify.py
+++ b/tests/extmod/ubinascii_unhexlify.py
@@ -4,9 +4,8 @@ try:
     except ImportError:
         import binascii
 except ImportError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 print(binascii.unhexlify(b'0001020304050607'))
 print(binascii.unhexlify(b'08090a0b0c0d0e0f'))
diff --git a/tests/extmod/uctypes_32bit_intbig.py b/tests/extmod/uctypes_32bit_intbig.py
index a082dc370..6b4d3d76c 100644
--- a/tests/extmod/uctypes_32bit_intbig.py
+++ b/tests/extmod/uctypes_32bit_intbig.py
@@ -3,9 +3,8 @@
 try:
     import uctypes
 except ImportError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 buf = b"12345678abcd"
 struct = uctypes.struct(
diff --git a/tests/extmod/uctypes_array_assign_le.py b/tests/extmod/uctypes_array_assign_le.py
index bae467d09..6afa7e0a2 100644
--- a/tests/extmod/uctypes_array_assign_le.py
+++ b/tests/extmod/uctypes_array_assign_le.py
@@ -1,9 +1,8 @@
 try:
     import uctypes
 except ImportError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 desc = {
     # arr is array at offset 0, of UINT8 elements, array size is 2
diff --git a/tests/extmod/uctypes_array_assign_native_le.py b/tests/extmod/uctypes_array_assign_native_le.py
index f0ecc0dad..a538bf9ad 100644
--- a/tests/extmod/uctypes_array_assign_native_le.py
+++ b/tests/extmod/uctypes_array_assign_native_le.py
@@ -3,11 +3,11 @@ try:
     import uctypes
 except ImportError:
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 if sys.byteorder != "little":
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 desc = {
     # arr is array at offset 0, of UINT8 elements, array size is 2
diff --git a/tests/extmod/uctypes_array_assign_native_le_intbig.py b/tests/extmod/uctypes_array_assign_native_le_intbig.py
index f29a3b66e..84dfba0e2 100644
--- a/tests/extmod/uctypes_array_assign_native_le_intbig.py
+++ b/tests/extmod/uctypes_array_assign_native_le_intbig.py
@@ -3,11 +3,11 @@ try:
     import uctypes
 except ImportError:
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 if sys.byteorder != "little":
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 desc = {
     # arr is array at offset 0, of UINT8 elements, array size is 2
diff --git a/tests/extmod/uctypes_bytearray.py b/tests/extmod/uctypes_bytearray.py
index bf7845ab2..61c7da271 100644
--- a/tests/extmod/uctypes_bytearray.py
+++ b/tests/extmod/uctypes_bytearray.py
@@ -1,9 +1,8 @@
 try:
     import uctypes
 except ImportError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 desc = {
     "arr": (uctypes.ARRAY | 0, uctypes.UINT8 | 2),
diff --git a/tests/extmod/uctypes_le.py b/tests/extmod/uctypes_le.py
index 829beda58..7df5ac090 100644
--- a/tests/extmod/uctypes_le.py
+++ b/tests/extmod/uctypes_le.py
@@ -1,9 +1,8 @@
 try:
     import uctypes
 except ImportError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 desc = {
     "s0": uctypes.UINT16 | 0,
diff --git a/tests/extmod/uctypes_le_float.py b/tests/extmod/uctypes_le_float.py
index a61305ba8..84ff2b84c 100644
--- a/tests/extmod/uctypes_le_float.py
+++ b/tests/extmod/uctypes_le_float.py
@@ -1,9 +1,8 @@
 try:
     import uctypes
 except ImportError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 desc = {
     "f32": uctypes.FLOAT32 | 0,
diff --git a/tests/extmod/uctypes_native_float.py b/tests/extmod/uctypes_native_float.py
index 80cb54383..acef47036 100644
--- a/tests/extmod/uctypes_native_float.py
+++ b/tests/extmod/uctypes_native_float.py
@@ -1,9 +1,8 @@
 try:
     import uctypes
 except ImportError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 desc = {
     "f32": uctypes.FLOAT32 | 0,
diff --git a/tests/extmod/uctypes_native_le.py b/tests/extmod/uctypes_native_le.py
index 5900224d4..8bba03b38 100644
--- a/tests/extmod/uctypes_native_le.py
+++ b/tests/extmod/uctypes_native_le.py
@@ -6,11 +6,11 @@ try:
     import uctypes
 except ImportError:
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 if sys.byteorder != "little":
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 
 desc = {
diff --git a/tests/extmod/uctypes_print.py b/tests/extmod/uctypes_print.py
index 76a009dc7..c310238e5 100644
--- a/tests/extmod/uctypes_print.py
+++ b/tests/extmod/uctypes_print.py
@@ -2,9 +2,8 @@
 try:
     import uctypes
 except ImportError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 # we use an address of "0" because we just want to print something deterministic
 # and don't actually need to set/get any values in the struct
diff --git a/tests/extmod/uctypes_ptr_le.py b/tests/extmod/uctypes_ptr_le.py
index e8a6243ce..056e45650 100644
--- a/tests/extmod/uctypes_ptr_le.py
+++ b/tests/extmod/uctypes_ptr_le.py
@@ -3,11 +3,11 @@ try:
     import uctypes
 except ImportError:
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 if sys.byteorder != "little":
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 desc = {
     "ptr": (uctypes.PTR | 0, uctypes.UINT8),
diff --git a/tests/extmod/uctypes_ptr_native_le.py b/tests/extmod/uctypes_ptr_native_le.py
index 9b016c04d..24508b1cb 100644
--- a/tests/extmod/uctypes_ptr_native_le.py
+++ b/tests/extmod/uctypes_ptr_native_le.py
@@ -3,11 +3,11 @@ try:
     import uctypes
 except ImportError:
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 if sys.byteorder != "little":
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 
 desc = {
diff --git a/tests/extmod/uctypes_sizeof.py b/tests/extmod/uctypes_sizeof.py
index 266cd0694..5a6adb437 100644
--- a/tests/extmod/uctypes_sizeof.py
+++ b/tests/extmod/uctypes_sizeof.py
@@ -1,9 +1,8 @@
 try:
     import uctypes
 except ImportError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 desc = {
     # arr is array at offset 0, of UINT8 elements, array size is 2
diff --git a/tests/extmod/uctypes_sizeof_native.py b/tests/extmod/uctypes_sizeof_native.py
index f676c8c6d..32c740e77 100644
--- a/tests/extmod/uctypes_sizeof_native.py
+++ b/tests/extmod/uctypes_sizeof_native.py
@@ -1,9 +1,8 @@
 try:
     import uctypes
 except ImportError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 S1 = {}
 assert uctypes.sizeof(S1) == 0
diff --git a/tests/extmod/uhashlib_sha1.py b/tests/extmod/uhashlib_sha1.py
index f12fc649a..4f7066899 100644
--- a/tests/extmod/uhashlib_sha1.py
+++ b/tests/extmod/uhashlib_sha1.py
@@ -1,4 +1,3 @@
-import sys
 try:
     import uhashlib as hashlib
 except ImportError:
@@ -8,14 +7,14 @@ except ImportError:
         # This is neither uPy, nor cPy, so must be uPy with
         # uhashlib module disabled.
         print("SKIP")
-        sys.exit()
+        raise SystemExit
 
 try:
     hashlib.sha1
 except AttributeError:
     # SHA1 is only available on some ports
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 sha1 = hashlib.sha1(b'hello')
 sha1.update(b'world')
diff --git a/tests/extmod/uhashlib_sha256.py b/tests/extmod/uhashlib_sha256.py
index ff51f2ffa..3200e8f5c 100644
--- a/tests/extmod/uhashlib_sha256.py
+++ b/tests/extmod/uhashlib_sha256.py
@@ -1,4 +1,3 @@
-import sys
 try:
     import uhashlib as hashlib
 except ImportError:
@@ -8,7 +7,7 @@ except ImportError:
         # This is neither uPy, nor cPy, so must be uPy with
         # uhashlib module disabled.
         print("SKIP")
-        sys.exit()
+        raise SystemExit
 
 
 h = hashlib.sha256()
diff --git a/tests/extmod/uheapq1.py b/tests/extmod/uheapq1.py
index 4b0e5de57..7c1fe4e1e 100644
--- a/tests/extmod/uheapq1.py
+++ b/tests/extmod/uheapq1.py
@@ -4,9 +4,8 @@ except:
     try:
         import heapq
     except ImportError:
-        import sys
         print("SKIP")
-        sys.exit()
+        raise SystemExit
 
 try:
     heapq.heappop([])
diff --git a/tests/extmod/ujson_dumps.py b/tests/extmod/ujson_dumps.py
index 4a02f5170..d73271801 100644
--- a/tests/extmod/ujson_dumps.py
+++ b/tests/extmod/ujson_dumps.py
@@ -4,9 +4,8 @@ except ImportError:
     try:
         import json
     except ImportError:
-        import sys
         print("SKIP")
-        sys.exit()
+        raise SystemExit
 
 print(json.dumps(False))
 print(json.dumps(True))
diff --git a/tests/extmod/ujson_dumps_extra.py b/tests/extmod/ujson_dumps_extra.py
index a52e8224c..21a388c32 100644
--- a/tests/extmod/ujson_dumps_extra.py
+++ b/tests/extmod/ujson_dumps_extra.py
@@ -3,8 +3,7 @@
 try:
     import ujson
 except ImportError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 print(ujson.dumps(b'1234'))
diff --git a/tests/extmod/ujson_dumps_float.py b/tests/extmod/ujson_dumps_float.py
index d949ea6dd..e8cceb6f1 100644
--- a/tests/extmod/ujson_dumps_float.py
+++ b/tests/extmod/ujson_dumps_float.py
@@ -4,8 +4,7 @@ except ImportError:
     try:
         import json
     except ImportError:
-        import sys
         print("SKIP")
-        sys.exit()
+        raise SystemExit
 
 print(json.dumps(1.2))
diff --git a/tests/extmod/ujson_load.py b/tests/extmod/ujson_load.py
index 901132a5f..9725ab2dd 100644
--- a/tests/extmod/ujson_load.py
+++ b/tests/extmod/ujson_load.py
@@ -6,9 +6,8 @@ except:
         from io import StringIO
         import json
     except ImportError:
-        import sys
         print("SKIP")
-        sys.exit()
+        raise SystemExit
 
 print(json.load(StringIO('null')))
 print(json.load(StringIO('"abc\\u0064e"')))
diff --git a/tests/extmod/ujson_loads.py b/tests/extmod/ujson_loads.py
index b2e18e3af..adba3c068 100644
--- a/tests/extmod/ujson_loads.py
+++ b/tests/extmod/ujson_loads.py
@@ -4,9 +4,8 @@ except ImportError:
     try:
         import json
     except ImportError:
-        import sys
         print("SKIP")
-        sys.exit()
+        raise SystemExit
 
 def my_print(o):
     if isinstance(o, dict):
diff --git a/tests/extmod/ujson_loads_float.py b/tests/extmod/ujson_loads_float.py
index b20a412ff..f1b8cc364 100644
--- a/tests/extmod/ujson_loads_float.py
+++ b/tests/extmod/ujson_loads_float.py
@@ -4,9 +4,8 @@ except ImportError:
     try:
         import json
     except ImportError:
-        import sys
         print("SKIP")
-        sys.exit()
+        raise SystemExit
 
 def my_print(o):
     print('%.3f' % o)
diff --git a/tests/extmod/urandom_basic.py b/tests/extmod/urandom_basic.py
index 885b8517f..57e6b26cb 100644
--- a/tests/extmod/urandom_basic.py
+++ b/tests/extmod/urandom_basic.py
@@ -4,9 +4,8 @@ except ImportError:
     try:
         import random
     except ImportError:
-        import sys
         print("SKIP")
-        sys.exit()
+        raise SystemExit
 
 # check getrandbits returns a value within the bit range
 for b in (1, 2, 3, 4, 16, 32):
diff --git a/tests/extmod/urandom_extra.py b/tests/extmod/urandom_extra.py
index 925dd0dbc..f5a34e168 100644
--- a/tests/extmod/urandom_extra.py
+++ b/tests/extmod/urandom_extra.py
@@ -4,16 +4,14 @@ except ImportError:
     try:
         import random
     except ImportError:
-        import sys
         print("SKIP")
-        sys.exit()
+        raise SystemExit
 
 try:
     random.randint
 except AttributeError:
-    import sys
     print('SKIP')
-    sys.exit()
+    raise SystemExit
 
 print('randrange')
 for i in range(50):
diff --git a/tests/extmod/ure1.py b/tests/extmod/ure1.py
index a867f1751..1f38b8087 100644
--- a/tests/extmod/ure1.py
+++ b/tests/extmod/ure1.py
@@ -4,9 +4,8 @@ except ImportError:
     try:
         import re
     except ImportError:
-        import sys
         print("SKIP")
-        sys.exit()
+        raise SystemExit
 
 r = re.compile(".+")
 m = r.match("abc")
diff --git a/tests/extmod/ure_debug.py b/tests/extmod/ure_debug.py
index 252df21e3..cfb264bb6 100644
--- a/tests/extmod/ure_debug.py
+++ b/tests/extmod/ure_debug.py
@@ -2,8 +2,7 @@
 try:
     import ure
 except ImportError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 ure.compile('^a|b[0-9]\w$', ure.DEBUG)
diff --git a/tests/extmod/ure_error.py b/tests/extmod/ure_error.py
index 3f16f9158..f52f735c7 100644
--- a/tests/extmod/ure_error.py
+++ b/tests/extmod/ure_error.py
@@ -6,9 +6,8 @@ except ImportError:
     try:
         import re
     except ImportError:
-        import sys
         print("SKIP")
-        sys.exit()
+        raise SystemExit
 
 def test_re(r):
     try:
diff --git a/tests/extmod/ure_group.py b/tests/extmod/ure_group.py
index 98aae2a73..4e39468c5 100644
--- a/tests/extmod/ure_group.py
+++ b/tests/extmod/ure_group.py
@@ -6,9 +6,8 @@ except ImportError:
     try:
         import re
     except ImportError:
-        import sys
         print("SKIP")
-        sys.exit()
+        raise SystemExit
 
 def print_groups(match):
     print('----')
diff --git a/tests/extmod/ure_namedclass.py b/tests/extmod/ure_namedclass.py
index e233f17c8..215d09613 100644
--- a/tests/extmod/ure_namedclass.py
+++ b/tests/extmod/ure_namedclass.py
@@ -6,9 +6,8 @@ except ImportError:
     try:
         import re
     except ImportError:
-        import sys
         print("SKIP")
-        sys.exit()
+        raise SystemExit
 
 def print_groups(match):
     print('----')
diff --git a/tests/extmod/ure_split.py b/tests/extmod/ure_split.py
index 1e411c27c..317ca9892 100644
--- a/tests/extmod/ure_split.py
+++ b/tests/extmod/ure_split.py
@@ -4,9 +4,8 @@ except ImportError:
     try:
         import re
     except ImportError:
-        import sys
         print("SKIP")
-        sys.exit()
+        raise SystemExit
 
 r = re.compile(" ")
 s = r.split("a b c foobar")
diff --git a/tests/extmod/ure_split_empty.py b/tests/extmod/ure_split_empty.py
index ad6334eba..76ce97ea6 100644
--- a/tests/extmod/ure_split_empty.py
+++ b/tests/extmod/ure_split_empty.py
@@ -7,9 +7,8 @@
 try:
     import ure as re
 except ImportError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 r = re.compile(" *")
 s = r.split("a b    c   foobar")
diff --git a/tests/extmod/ure_split_notimpl.py b/tests/extmod/ure_split_notimpl.py
index eca3ea512..da6e9652d 100644
--- a/tests/extmod/ure_split_notimpl.py
+++ b/tests/extmod/ure_split_notimpl.py
@@ -1,9 +1,8 @@
 try:
     import ure as re
 except ImportError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 r = re.compile('( )')
 try:
diff --git a/tests/extmod/ussl_basic.py b/tests/extmod/ussl_basic.py
index e9d435bca..9f8019a0b 100644
--- a/tests/extmod/ussl_basic.py
+++ b/tests/extmod/ussl_basic.py
@@ -5,8 +5,7 @@ try:
     import ussl as ssl
 except ImportError:
     print("SKIP")
-    import sys
-    sys.exit()
+    raise SystemExit
 
 # create in client mode
 try:
diff --git a/tests/extmod/utimeq1.py b/tests/extmod/utimeq1.py
index 68d69e25e..dc7f3b660 100644
--- a/tests/extmod/utimeq1.py
+++ b/tests/extmod/utimeq1.py
@@ -5,8 +5,7 @@ try:
     from utimeq import utimeq
 except ImportError:
     print("SKIP")
-    import sys
-    sys.exit()
+    raise SystemExit
 
 DEBUG = 0
 
diff --git a/tests/extmod/utimeq_stable.py b/tests/extmod/utimeq_stable.py
index 9f6ba76d4..9fb522d51 100644
--- a/tests/extmod/utimeq_stable.py
+++ b/tests/extmod/utimeq_stable.py
@@ -2,8 +2,7 @@ try:
     from utimeq import utimeq
 except ImportError:
     print("SKIP")
-    import sys
-    sys.exit()
+    raise SystemExit
 
 h = utimeq(10)
 
diff --git a/tests/extmod/uzlib_decompio.py b/tests/extmod/uzlib_decompio.py
index 6f07c048c..112a82597 100644
--- a/tests/extmod/uzlib_decompio.py
+++ b/tests/extmod/uzlib_decompio.py
@@ -2,9 +2,8 @@ try:
     import uzlib as zlib
     import uio as io
 except ImportError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 
 # Raw DEFLATE bitstream
diff --git a/tests/extmod/uzlib_decompio_gz.py b/tests/extmod/uzlib_decompio_gz.py
index 7572e9693..02087f763 100644
--- a/tests/extmod/uzlib_decompio_gz.py
+++ b/tests/extmod/uzlib_decompio_gz.py
@@ -2,9 +2,8 @@ try:
     import uzlib as zlib
     import uio as io
 except ImportError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 
 # gzip bitstream
diff --git a/tests/extmod/uzlib_decompress.py b/tests/extmod/uzlib_decompress.py
index 10121ee7e..63247955c 100644
--- a/tests/extmod/uzlib_decompress.py
+++ b/tests/extmod/uzlib_decompress.py
@@ -4,9 +4,8 @@ except ImportError:
     try:
         import uzlib as zlib
     except ImportError:
-        import sys
         print("SKIP")
-        sys.exit()
+        raise SystemExit
 
 PATTERNS = [
     # Packed results produced by CPy's zlib.compress()
diff --git a/tests/extmod/vfs_basic.py b/tests/extmod/vfs_basic.py
index a3b2f3c29..4fc67d34b 100644
--- a/tests/extmod/vfs_basic.py
+++ b/tests/extmod/vfs_basic.py
@@ -9,8 +9,7 @@ try:
     uos.mount
 except (ImportError, AttributeError):
     print("SKIP")
-    import sys
-    sys.exit()
+    raise SystemExit
 
 
 class Filesystem:
@@ -57,6 +56,9 @@ for path in uos.listdir('/'):
 # stat root dir
 print(uos.stat('/'))
 
+# statvfs root dir; verify that f_namemax has a sensible size
+print(uos.statvfs('/')[9] >= 32)
+
 # getcwd when in root dir
 print(uos.getcwd())
 
@@ -128,6 +130,8 @@ except OSError:
 
 # root dir
 uos.mount(Filesystem(3), '/')
+print(uos.stat('/'))
+print(uos.statvfs('/'))
 print(uos.listdir())
 open('test')
 
diff --git a/tests/extmod/vfs_basic.py.exp b/tests/extmod/vfs_basic.py.exp
index 8a23aa8ae..0ae2c2cc9 100644
--- a/tests/extmod/vfs_basic.py.exp
+++ b/tests/extmod/vfs_basic.py.exp
@@ -1,4 +1,5 @@
 (16384, 0, 0, 0, 0, 0, 0, 0, 0, 0)
+True
 /
 1 mount False False
 ['test_mnt']
@@ -36,6 +37,9 @@ OSError
 2 umount
 OSError
 3 mount False False
+(16384, 0, 0, 0, 0, 0, 0, 0, 0, 0)
+3 statvfs /
+(3,)
 3 ilistdir /
 ['a3']
 3 open test r
diff --git a/tests/extmod/vfs_fat_fileio1.py b/tests/extmod/vfs_fat_fileio1.py
index 9036df7a5..d19df120b 100644
--- a/tests/extmod/vfs_fat_fileio1.py
+++ b/tests/extmod/vfs_fat_fileio1.py
@@ -1,4 +1,3 @@
-import sys
 try:
     import uerrno
     try:
@@ -8,13 +7,13 @@ try:
         import uos
 except ImportError:
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 try:
     uos.VfsFat
 except AttributeError:
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 
 class RAMFS:
@@ -46,7 +45,7 @@ try:
     bdev = RAMFS(50)
 except MemoryError:
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 uos.VfsFat.mkfs(bdev)
 vfs = uos.VfsFat(bdev)
diff --git a/tests/extmod/vfs_fat_fileio2.py b/tests/extmod/vfs_fat_fileio2.py
index b2a0ba70f..b5adb75c9 100644
--- a/tests/extmod/vfs_fat_fileio2.py
+++ b/tests/extmod/vfs_fat_fileio2.py
@@ -1,4 +1,3 @@
-import sys
 try:
     import uerrno
     try:
@@ -8,13 +7,13 @@ try:
         import uos
 except ImportError:
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 try:
     uos.VfsFat
 except AttributeError:
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 
 class RAMFS:
@@ -46,7 +45,7 @@ try:
     bdev = RAMFS(50)
 except MemoryError:
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 uos.VfsFat.mkfs(bdev)
 vfs = uos.VfsFat(bdev)
diff --git a/tests/extmod/vfs_fat_more.py b/tests/extmod/vfs_fat_more.py
index dacb21553..baec96787 100644
--- a/tests/extmod/vfs_fat_more.py
+++ b/tests/extmod/vfs_fat_more.py
@@ -1,4 +1,3 @@
-import sys
 import uerrno
 try:
     try:
@@ -8,13 +7,13 @@ try:
         import uos
 except ImportError:
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 try:
     uos.VfsFat
 except AttributeError:
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 
 class RAMFS:
@@ -47,7 +46,7 @@ try:
     bdev2 = RAMFS(50)
 except MemoryError:
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 # first we umount any existing mount points the target may have
 try:
diff --git a/tests/extmod/vfs_fat_oldproto.py b/tests/extmod/vfs_fat_oldproto.py
index 3e66758c3..ef4f1da78 100644
--- a/tests/extmod/vfs_fat_oldproto.py
+++ b/tests/extmod/vfs_fat_oldproto.py
@@ -1,4 +1,3 @@
-import sys
 try:
     import uerrno
     try:
@@ -7,13 +6,13 @@ try:
         import uos
 except ImportError:
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 try:
     uos.VfsFat
 except AttributeError:
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 class RAMFS_OLD:
 
@@ -43,7 +42,7 @@ try:
     bdev = RAMFS_OLD(50)
 except MemoryError:
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 uos.VfsFat.mkfs(bdev)
 vfs = uos.VfsFat(bdev)
diff --git a/tests/extmod/vfs_fat_ramdisk.py b/tests/extmod/vfs_fat_ramdisk.py
index fe72a8bef..801c69786 100644
--- a/tests/extmod/vfs_fat_ramdisk.py
+++ b/tests/extmod/vfs_fat_ramdisk.py
@@ -1,4 +1,3 @@
-import sys
 try:
     import uerrno
     try:
@@ -7,13 +6,13 @@ try:
         import uos
 except ImportError:
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 try:
     uos.VfsFat
 except AttributeError:
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 
 class RAMFS:
@@ -45,7 +44,7 @@ try:
     bdev = RAMFS(50)
 except MemoryError:
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 uos.VfsFat.mkfs(bdev)
 
diff --git a/tests/extmod/websocket_basic.py b/tests/extmod/websocket_basic.py
index 770836c8e..9a80503a0 100644
--- a/tests/extmod/websocket_basic.py
+++ b/tests/extmod/websocket_basic.py
@@ -3,9 +3,8 @@ try:
     import uerrno
     import websocket
 except ImportError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 # put raw data in the stream and do a websocket read
 def ws_read(msg, sz):
diff --git a/tests/float/array_construct.py b/tests/float/array_construct.py
index 7e01fd476..938675835 100644
--- a/tests/float/array_construct.py
+++ b/tests/float/array_construct.py
@@ -3,9 +3,8 @@
 try:
     from array import array
 except ImportError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 print(array('f', array('h', [1, 2])))
 print(array('d', array('f', [1, 2])))
diff --git a/tests/float/builtin_float_minmax.py b/tests/float/builtin_float_minmax.py
index 42cfa6382..266ed133d 100644
--- a/tests/float/builtin_float_minmax.py
+++ b/tests/float/builtin_float_minmax.py
@@ -3,31 +3,30 @@ try:
     min
     max
 except:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
-print(min(0,1.0))
-print(min(1.0,0))
-print(min(0,-1.0))
-print(min(-1.0,0))
+print(min(0, 1.0))
+print(min(1.0, 0))
+print(min(0, -1.0))
+print(min(-1.0, 0))
 
-print(max(0,1.0))
-print(max(1.0,0))
-print(max(0,-1.0))
-print(max(-1.0,0))
+print(max(0, 1.0))
+print(max(1.0, 0))
+print(max(0, -1.0))
+print(max(-1.0, 0))
 
-print(min(1.5,-1.5))
-print(min(-1.5,1.5))
+print(min(1.5, -1.5))
+print(min(-1.5, 1.5))
 
-print(max(1.5,-1.5))
-print(max(-1.5,1.5))
+print(max(1.5, -1.5))
+print(max(-1.5, 1.5))
 
-print(min([1,2.9,4,0,-1,2]))
-print(max([1,2.9,4,0,-1,2]))
+print(min([1, 2.9, 4, 0, -1, 2]))
+print(max([1, 2.9, 4, 0, -1, 2]))
 
-print(min([1,2.9,4,6.5,-1,2]))
-print(max([1,2.9,4,6.5,-1,2]))
-print(min([1,2.9,4,-6.5,-1,2]))
-print(max([1,2.9,4,-6.5,-1,2]))
+print(min([1, 2.9, 4, 6.5, -1, 2]))
+print(max([1, 2.9, 4, 6.5, -1, 2]))
+print(min([1, 2.9, 4, -6.5, -1, 2]))
+print(max([1, 2.9, 4, -6.5, -1, 2]))
 
diff --git a/tests/float/bytearray_construct.py b/tests/float/bytearray_construct.py
index db946a99d..e960d624e 100644
--- a/tests/float/bytearray_construct.py
+++ b/tests/float/bytearray_construct.py
@@ -3,8 +3,7 @@
 try:
     from array import array
 except ImportError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 print(bytearray(array('f', [1, 2.3])))
diff --git a/tests/float/bytes_construct.py b/tests/float/bytes_construct.py
index 8664d7296..0e4482e43 100644
--- a/tests/float/bytes_construct.py
+++ b/tests/float/bytes_construct.py
@@ -3,8 +3,7 @@
 try:
     from array import array
 except ImportError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 print(bytes(array('f', [1, 2.3])))
diff --git a/tests/float/cmath_fun.py b/tests/float/cmath_fun.py
index 3ebcf5918..ae5921c30 100644
--- a/tests/float/cmath_fun.py
+++ b/tests/float/cmath_fun.py
@@ -4,8 +4,7 @@ try:
     from cmath import *
 except ImportError:
     print("SKIP")
-    import sys
-    sys.exit()
+    raise SystemExit
 
 # make sure these constants exist in cmath
 print("%.5g" % e)
diff --git a/tests/float/cmath_fun_special.py b/tests/float/cmath_fun_special.py
index 422964dd7..471fda8c0 100644
--- a/tests/float/cmath_fun_special.py
+++ b/tests/float/cmath_fun_special.py
@@ -5,8 +5,7 @@ try:
     log10
 except (ImportError, NameError):
     print("SKIP")
-    import sys
-    sys.exit()
+    raise SystemExit
 
 test_values_non_zero = []
 base_values = (0.0, 0.5, 1.2345, 10.)
diff --git a/tests/float/float_array.py b/tests/float/float_array.py
index 8bc963444..8c8edcff7 100644
--- a/tests/float/float_array.py
+++ b/tests/float/float_array.py
@@ -1,9 +1,8 @@
 try:
     from array import array
 except ImportError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 def test(a):
     print(a)
diff --git a/tests/float/float_struct.py b/tests/float/float_struct.py
index a36ccce38..c4c186b89 100644
--- a/tests/float/float_struct.py
+++ b/tests/float/float_struct.py
@@ -5,9 +5,8 @@ try:
     except:
         import struct
 except ImportError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 i = 1. + 1/2
 # TODO: it looks like '=' format modifier is not yet supported
diff --git a/tests/float/math_fun.py b/tests/float/math_fun.py
index d9f179587..80d20bd8a 100644
--- a/tests/float/math_fun.py
+++ b/tests/float/math_fun.py
@@ -4,8 +4,7 @@ try:
     from math import *
 except ImportError:
     print("SKIP")
-    import sys
-    sys.exit()
+    raise SystemExit
 
 test_values = [-100., -1.23456, -1, -0.5, 0.0, 0.5, 1.23456, 100.]
 test_values_small = [-10., -1.23456, -1, -0.5, 0.0, 0.5, 1.23456, 10.] # so we don't overflow 32-bit precision
diff --git a/tests/float/math_fun_bool.py b/tests/float/math_fun_bool.py
index 57232857a..30ab14a52 100644
--- a/tests/float/math_fun_bool.py
+++ b/tests/float/math_fun_bool.py
@@ -4,8 +4,7 @@ try:
     from math import isfinite, isnan, isinf
 except ImportError:
     print("SKIP")
-    import sys
-    sys.exit()
+    raise SystemExit
 
 test_values = [1, 0, -1, 1.0, 0.0, -1.0, float('NaN'), float('Inf'), 
                -float('NaN'), -float('Inf')]
diff --git a/tests/float/math_fun_int.py b/tests/float/math_fun_int.py
index ee54f0995..5cadbb1e5 100644
--- a/tests/float/math_fun_int.py
+++ b/tests/float/math_fun_int.py
@@ -4,8 +4,7 @@ try:
     import math
 except ImportError:
     print("SKIP")
-    import sys
-    sys.exit()
+    raise SystemExit
 
 for fun in (math.ceil, math.floor, math.trunc):
     for x in (-1.6, -0.2, 0, 0.6, 1.4, float('inf'), float('nan')):
diff --git a/tests/float/math_fun_intbig.py b/tests/float/math_fun_intbig.py
index 962c10daa..697ca7a6d 100644
--- a/tests/float/math_fun_intbig.py
+++ b/tests/float/math_fun_intbig.py
@@ -4,8 +4,7 @@ try:
     import math
 except ImportError:
     print("SKIP")
-    import sys
-    sys.exit()
+    raise SystemExit
 
 for fun in (math.ceil, math.floor, math.trunc):
     for x in (-1e25, 1e25):
diff --git a/tests/float/math_fun_special.py b/tests/float/math_fun_special.py
index 32249b423..c3665a7cd 100644
--- a/tests/float/math_fun_special.py
+++ b/tests/float/math_fun_special.py
@@ -5,8 +5,7 @@ try:
     erf
 except (ImportError, NameError):
     print("SKIP")
-    import sys
-    sys.exit()
+    raise SystemExit
 
 test_values = [-8., -2.5, -1, -0.5, 0.0, 0.5, 2.5, 8.,]
 pos_test_values = [0.001, 0.1, 0.5, 1.0, 1.5, 10.,]
diff --git a/tests/io/buffered_writer.py b/tests/io/buffered_writer.py
index bb7b4e8db..c2cedb991 100644
--- a/tests/io/buffered_writer.py
+++ b/tests/io/buffered_writer.py
@@ -4,9 +4,8 @@ try:
     io.BytesIO
     io.BufferedWriter
 except AttributeError:
-    import sys
     print('SKIP')
-    sys.exit()
+    raise SystemExit
 
 bts = io.BytesIO()
 buf = io.BufferedWriter(bts, 8)
diff --git a/tests/io/bytesio_cow.py b/tests/io/bytesio_cow.py
new file mode 100644
index 000000000..92654a000
--- /dev/null
+++ b/tests/io/bytesio_cow.py
@@ -0,0 +1,20 @@
+# Make sure that write operations on io.BytesIO don't
+# change original object it was constructed from.
+try:
+    import uio as io
+except ImportError:
+    import io
+
+b = b"foobar"
+
+a = io.BytesIO(b)
+a.write(b"1")
+print(b)
+print(a.getvalue())
+
+b = bytearray(b"foobar")
+
+a = io.BytesIO(b)
+a.write(b"1")
+print(b)
+print(a.getvalue())
diff --git a/tests/io/open_append.py b/tests/io/open_append.py
index 2120b72f0..a696823bc 100644
--- a/tests/io/open_append.py
+++ b/tests/io/open_append.py
@@ -1,4 +1,3 @@
-import sys
 try:
     import uos as os
 except ImportError:
@@ -6,7 +5,7 @@ except ImportError:
 
 if not hasattr(os, "unlink"):
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 # cleanup in case testfile exists
 try:
diff --git a/tests/io/open_plus.py b/tests/io/open_plus.py
index 98598ee67..bba96fa2f 100644
--- a/tests/io/open_plus.py
+++ b/tests/io/open_plus.py
@@ -1,4 +1,3 @@
-import sys
 try:
     import uos as os
 except ImportError:
@@ -6,7 +5,7 @@ except ImportError:
 
 if not hasattr(os, "unlink"):
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 # cleanup in case testfile exists
 try:
diff --git a/tests/io/resource_stream.py b/tests/io/resource_stream.py
index 86975f118..37d985bf1 100644
--- a/tests/io/resource_stream.py
+++ b/tests/io/resource_stream.py
@@ -5,7 +5,7 @@ try:
     uio.resource_stream
 except AttributeError:
     print('SKIP')
-    sys.exit()
+    raise SystemExit
 
 buf = uio.resource_stream("data", "file2")
 print(buf.read())
diff --git a/tests/io/write_ext.py b/tests/io/write_ext.py
index 19b616174..5a6eaa35c 100644
--- a/tests/io/write_ext.py
+++ b/tests/io/write_ext.py
@@ -5,9 +5,8 @@ import uio
 try:
     uio.BytesIO
 except AttributeError:
-    import sys
     print('SKIP')
-    sys.exit()
+    raise SystemExit
 
 buf = uio.BytesIO()
 
diff --git a/tests/jni/list.py b/tests/jni/list.py
index 6725abb5a..d58181d0b 100644
--- a/tests/jni/list.py
+++ b/tests/jni/list.py
@@ -1,10 +1,9 @@
-import sys
 import jni
 try:
     ArrayList = jni.cls("java/util/ArrayList")
 except:
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 l = ArrayList()
 print(l)
diff --git a/tests/jni/object.py b/tests/jni/object.py
index 6cf936c4d..aa67615ec 100644
--- a/tests/jni/object.py
+++ b/tests/jni/object.py
@@ -1,10 +1,9 @@
-import sys
 import jni
 try:
     Integer = jni.cls("java/lang/Integer")
 except:
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 # Create object
 i = Integer(42)
diff --git a/tests/jni/system_out.py b/tests/jni/system_out.py
index 7a1f18030..86c4b9e11 100644
--- a/tests/jni/system_out.py
+++ b/tests/jni/system_out.py
@@ -1,9 +1,8 @@
-import sys
 try:
     import jni
     System = jni.cls("java/lang/System")
 except:
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 System.out.println("Hello, Java!")
diff --git a/tests/micropython/heapalloc_bytesio.py b/tests/micropython/heapalloc_bytesio.py
index 2a8d50abe..4aae2abf0 100644
--- a/tests/micropython/heapalloc_bytesio.py
+++ b/tests/micropython/heapalloc_bytesio.py
@@ -1,9 +1,8 @@
 try:
     import uio
 except ImportError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 import micropython
 
diff --git a/tests/micropython/heapalloc_bytesio2.py b/tests/micropython/heapalloc_bytesio2.py
new file mode 100644
index 000000000..cd76f5807
--- /dev/null
+++ b/tests/micropython/heapalloc_bytesio2.py
@@ -0,0 +1,20 @@
+# Creating BytesIO from immutable object should not immediately
+# copy its content.
+try:
+    import uio
+    import micropython
+    micropython.mem_total
+except (ImportError, AttributeError):
+    print("SKIP")
+    raise SystemExit
+
+
+data = b"1234" * 256
+
+before = micropython.mem_total()
+
+buf = uio.BytesIO(data)
+
+after = micropython.mem_total()
+
+print(after - before < len(data))
diff --git a/tests/micropython/heapalloc_bytesio2.py.exp b/tests/micropython/heapalloc_bytesio2.py.exp
new file mode 100644
index 000000000..0ca95142b
--- /dev/null
+++ b/tests/micropython/heapalloc_bytesio2.py.exp
@@ -0,0 +1 @@
+True
diff --git a/tests/micropython/heapalloc_iter.py b/tests/micropython/heapalloc_iter.py
index 45d3519e4..79461f999 100644
--- a/tests/micropython/heapalloc_iter.py
+++ b/tests/micropython/heapalloc_iter.py
@@ -2,9 +2,8 @@
 try:
     import array
 except ImportError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 try:
     from micropython import heap_lock, heap_unlock
diff --git a/tests/micropython/heapalloc_traceback.py b/tests/micropython/heapalloc_traceback.py
index b3795293f..f4212b6ce 100644
--- a/tests/micropython/heapalloc_traceback.py
+++ b/tests/micropython/heapalloc_traceback.py
@@ -5,9 +5,8 @@ import sys
 try:
     import uio
 except ImportError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 # preallocate exception instance with some room for a traceback
 global_exc = StopIteration()
diff --git a/tests/micropython/heapalloc_traceback.py.exp b/tests/micropython/heapalloc_traceback.py.exp
index facd0af13..291bbd697 100644
--- a/tests/micropython/heapalloc_traceback.py.exp
+++ b/tests/micropython/heapalloc_traceback.py.exp
@@ -1,5 +1,5 @@
 StopIteration
 Traceback (most recent call last):
-  File  , line 23, in test
+  File  , line 22, in test
 StopIteration: 
 
diff --git a/tests/micropython/kbd_intr.py b/tests/micropython/kbd_intr.py
index a7ce7464b..879c9a229 100644
--- a/tests/micropython/kbd_intr.py
+++ b/tests/micropython/kbd_intr.py
@@ -6,8 +6,7 @@ try:
     micropython.kbd_intr
 except AttributeError:
     print('SKIP')
-    import sys
-    sys.exit()
+    raise SystemExit
 
 # just check we can actually call it
 micropython.kbd_intr(3)
diff --git a/tests/micropython/schedule.py b/tests/micropython/schedule.py
index 3d584eea4..74f90cb2d 100644
--- a/tests/micropython/schedule.py
+++ b/tests/micropython/schedule.py
@@ -6,8 +6,7 @@ try:
     micropython.schedule
 except AttributeError:
     print('SKIP')
-    import sys
-    sys.exit()
+    raise SystemExit
 
 # Basic test of scheduling a function.
 
diff --git a/tests/misc/non_compliant.py b/tests/misc/non_compliant.py
index 31074ab01..b4c90e9fc 100644
--- a/tests/misc/non_compliant.py
+++ b/tests/misc/non_compliant.py
@@ -4,9 +4,8 @@ try:
     import array
     import ustruct
 except ImportError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 # when super can't find self
 try:
diff --git a/tests/misc/print_exception.py b/tests/misc/print_exception.py
index b833a7981..9ab8e728b 100644
--- a/tests/misc/print_exception.py
+++ b/tests/misc/print_exception.py
@@ -6,7 +6,7 @@ try:
         import io
 except ImportError:
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 if hasattr(sys, 'print_exception'):
     print_exception = sys.print_exception
diff --git a/tests/misc/recursive_data.py b/tests/misc/recursive_data.py
index 383018945..3b7fa5095 100644
--- a/tests/misc/recursive_data.py
+++ b/tests/misc/recursive_data.py
@@ -2,9 +2,8 @@
 try:
     import uio as io
 except ImportError:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 l = [1, 2, 3, None]
 l[-1] = l
diff --git a/tests/misc/recursive_iternext.py b/tests/misc/recursive_iternext.py
index d90f17716..edb5a843f 100644
--- a/tests/misc/recursive_iternext.py
+++ b/tests/misc/recursive_iternext.py
@@ -6,9 +6,8 @@ try:
     max
     zip
 except:
-    import sys
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 # We need to pick an N that is large enough to hit the recursion
 # limit, but not too large that we run out of heap memory.
diff --git a/tests/misc/sys_exc_info.py b/tests/misc/sys_exc_info.py
index de5b82562..4bb2c61e8 100644
--- a/tests/misc/sys_exc_info.py
+++ b/tests/misc/sys_exc_info.py
@@ -3,7 +3,7 @@ try:
     sys.exc_info
 except:
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 def f():
     print(sys.exc_info()[0:2])
diff --git a/tests/pyb/can.py b/tests/pyb/can.py
index 617eb7ccc..0fd8c8368 100644
--- a/tests/pyb/can.py
+++ b/tests/pyb/can.py
@@ -2,8 +2,7 @@ try:
     from pyb import CAN
 except ImportError:
     print('SKIP')
-    import sys
-    sys.exit()
+    raise SystemExit
 
 import pyb
 
@@ -158,7 +157,7 @@ print(can.recv(1))
 
 del can
 
-# Testing asyncronous send
+# Testing asynchronous send
 can = CAN(1, CAN.LOOPBACK)
 can.setfilter(0, CAN.MASK16, 0, (0, 0, 0, 0))
 
diff --git a/tests/pyb/dac.py b/tests/pyb/dac.py
index 942f30354..6f03bbc64 100644
--- a/tests/pyb/dac.py
+++ b/tests/pyb/dac.py
@@ -2,8 +2,7 @@ import pyb
 
 if not hasattr(pyb, 'DAC'):
     print('SKIP')
-    import sys
-    sys.exit()
+    raise SystemExit
 
 dac = pyb.DAC(1)
 print(dac)
diff --git a/tests/pyb/pyb_f405.py b/tests/pyb/pyb_f405.py
index 3c81fe109..2f161ae09 100644
--- a/tests/pyb/pyb_f405.py
+++ b/tests/pyb/pyb_f405.py
@@ -4,8 +4,7 @@ import os, pyb
 
 if not 'STM32F405' in os.uname().machine:
     print('SKIP')
-    import sys
-    sys.exit()
+    raise SystemExit
 
 print(pyb.freq())
 print(type(pyb.rng()))
diff --git a/tests/pyb/pyb_f411.py b/tests/pyb/pyb_f411.py
index 328653965..50de30282 100644
--- a/tests/pyb/pyb_f411.py
+++ b/tests/pyb/pyb_f411.py
@@ -4,7 +4,6 @@ import os, pyb
 
 if not 'STM32F411' in os.uname().machine:
     print('SKIP')
-    import sys
-    sys.exit()
+    raise SystemExit
 
 print(pyb.freq())
diff --git a/tests/thread/stress_aes.py b/tests/thread/stress_aes.py
index ecc963c92..df75e616c 100644
--- a/tests/thread/stress_aes.py
+++ b/tests/thread/stress_aes.py
@@ -8,7 +8,7 @@
 #
 # The AES code comes first (code originates from a C version authored by D.P.George)
 # and then the test harness at the bottom.  It can be tuned to be more/less
-# agressive by changing the amount of data to encrypt, the number of loops and
+# aggressive by changing the amount of data to encrypt, the number of loops and
 # the number of threads.
 #
 # MIT license; Copyright (c) 2016 Damien P. George on behalf of Pycom Ltd
diff --git a/tests/unix/extra_coverage.py b/tests/unix/extra_coverage.py
index 870e7d5f2..7a496aa87 100644
--- a/tests/unix/extra_coverage.py
+++ b/tests/unix/extra_coverage.py
@@ -2,8 +2,7 @@ try:
     extra_coverage
 except NameError:
     print("SKIP")
-    import sys
-    sys.exit()
+    raise SystemExit
 
 import uerrno
 import uio
diff --git a/tests/unix/ffi_callback.py b/tests/unix/ffi_callback.py
index 7f8af15b3..23b058bce 100644
--- a/tests/unix/ffi_callback.py
+++ b/tests/unix/ffi_callback.py
@@ -1,9 +1,8 @@
-import sys
 try:
     import ffi
 except ImportError:
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 
 def ffi_open(names):
diff --git a/tests/unix/ffi_float.py b/tests/unix/ffi_float.py
index cc12fa7ad..c92a39bcd 100644
--- a/tests/unix/ffi_float.py
+++ b/tests/unix/ffi_float.py
@@ -1,10 +1,9 @@
 # test ffi float support
-import sys
 try:
     import ffi
 except ImportError:
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 
 def ffi_open(names):
diff --git a/tests/unix/ffi_float2.py b/tests/unix/ffi_float2.py
index d635a2714..721eb4d19 100644
--- a/tests/unix/ffi_float2.py
+++ b/tests/unix/ffi_float2.py
@@ -1,10 +1,9 @@
 # test ffi float support
-import sys
 try:
     import ffi
 except ImportError:
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 
 def ffi_open(names):
@@ -25,7 +24,7 @@ try:
     tgammaf = libm.func('f', 'tgammaf', 'f')
 except OSError:
     print("SKIP")
-    sys.exit()
+    raise SystemExit
 
 for fun in (tgammaf,):
     for val in (0.5, 1, 1.0, 1.5, 4, 4.0):
diff --git a/tests/wipy/uart.py b/tests/wipy/uart.py
index a3a1c14e8..8e794015d 100644
--- a/tests/wipy/uart.py
+++ b/tests/wipy/uart.py
@@ -95,7 +95,7 @@ print(uart1.read() == None)
 print(uart1.write(b'123') == 3)
 print(uart0.read() == b'123')
 
-# no pin assignemnt
+# no pin assignment
 uart0 = UART(0, 1000000, pins=(None, None))
 print(uart0.write(b'123456789') == 9)
 print(uart1.read() == None)