tests/import/builtin_ext.py: Add test for built-in module override.

This verifies the behavior:
 - Exact matches of built-ins bypass filesystem.
 - u-prefix modules can be overridden from the filesystem.
 - Builtin import can be forced using either u-prefix or sys.path=[].

This work was funded through GitHub Sponsors.

Signed-off-by: Jim Mussared <jim.mussared@gmail.com>

1 files changed, 36 insertions, 0 deletions

diff --git a/tests/import/builtin_ext.py b/tests/import/builtin_ext.py
new file mode 100644
index 000000000..dd8f95cbc
--- /dev/null
+++ b/tests/import/builtin_ext.py
@@ -0,0 +1,36 @@
+import sys
+
+print(sys, hasattr(sys, "__file__"))
+
+sys.path.clear()
+sys.path.append("ext")
+
+# All three should only get builtins, despite sys.py, usys.py, and
+# micropython.py being in the path.
+import micropython
+
+print(micropython, hasattr(micropython, "__file__"))
+import sys
+
+print(sys, hasattr(sys, "__file__"))
+import usys
+
+print(usys, hasattr(usys, "__file__"))
+
+# This should get os.py, which uses uos to get the builtin.
+import os
+
+print(os, hasattr(os, "__file__"), os.sep, os.extra)
+
+# This should get time.py, which uses empty sys.path to get the builtin.
+import time
+
+print(time, hasattr(time, "__file__"), time.sleep, time.extra)
+
+# These should get the builtins.
+import uos
+
+print(uos, hasattr(uos, "__file__"), hasattr(uos, "extra"))
+import utime
+
+print(utime, hasattr(utime, "__file__"), hasattr(utime, "extra"))