1 files changed, 57 insertions, 0 deletions
diff --git a/tests/basics/string_fstring.py b/tests/basics/string_fstring.py
new file mode 100644
index 000000000..efb7e5a8e
--- /dev/null
+++ b/tests/basics/string_fstring.py
@@ -0,0 +1,57 @@
+def f():
+    return 4
+def g(_):
+    return 5
+def h():
+    return 6
+
+print(f'no interpolation')
+print(f"no interpolation")
+print(f"""no interpolation""")
+
+x, y = 1, 2
+print(f'{x}')
+print(f'{x:08x}')
+print(f'{x=}')
+print(f'{x=:08x}')
+print(f'a {x} b {y} c')
+print(f'a {x:08x} b {y} c')
+print(f'a {x=} b {y} c')
+print(f'a {x=:08x} b {y} c')
+
+print(f'a {"hello"} b')
+print(f'a {f() + g("foo") + h()} b')
+print(f'a {f() + g("foo") + h()=} b')
+print(f'a {f() + g("foo") + h()=:08x} b')
+
+def foo(a, b):
+    return f'{x}{y}{a}{b}'
+print(foo(7, 8))
+
+# PEP-0498 specifies that '\\' and '#' must be disallowed explicitly, whereas
+# MicroPython relies on the syntax error as a result of the substitution.
+
+print(f"\\")
+print(f'#')
+try:
+    eval("f'{\}'")
+except SyntaxError:
+    print('SyntaxError')
+try:
+    eval("f'{#}'")
+except SyntaxError:
+    print('SyntaxError')
+
+
+# PEP-0498 specifies that handling of double braces '{{' or '}}' should
+# behave like str.format.
+print(f'{{}}')
+print(f'{{{4*10}}}', '{40}')
+
+# A single closing brace, unlike str.format should raise a syntax error.
+# MicroPython instead raises ValueError at runtime from the substitution.
+try:
+    eval("f'{{}'")
+except (ValueError, SyntaxError):
+    # MicroPython incorrectly raises ValueError here.
+    print('SyntaxError')