PEP 646: Add tests for syntax changes

mrahtz · Dec 3, 2021 · Jan 3, 2022 · Dec 7, 2021 · Dec 7, 2021 · Dec 7, 2021
commit b725671a14dd66d48a537a9b1e201561d7b5f7ea
diff --git a/Lib/test/test_pep646_syntax.py b/Lib/test/test_pep646_syntax.py
@@ -0,0 +1,158 @@
+doctests = """
+
+Setup
+
+    >>> class A:
+    ...    def __class_getitem__(cls, x):
+    ...        return ParameterisedA(x)
+    >>> class ParameterisedA:
+    ...    def __init__(self, params):
+    ...        self._params = params
+    ...    def __repr__(self):
+    ...        return f"A[{self._params}]"
+    ...    def __iter__(self):
+    ...        for p in self._params:
+    ...            yield p
+    >>> class B:
+    ...    def __iter__(self):
+    ...        yield StarredB()
+    ...    def __repr__(self):
+    ...        return "B"
+    >>> class StarredB:
+    ...    def __repr__(self):
+    ...        return "StarredB"
+    >>> b = B()
+
+Slices that are supposed to work, starring our custom B class
+
+    >>> A[*b]
+    A[(StarredB,)]
+    >>> A[*b, *b]
+    A[(StarredB, StarredB)]
+    >>> A[b, *b]
+    A[(B, StarredB)]
+    >>> A[*b, b]
+    A[(StarredB, B)]
+    >>> A[b, b, *b]
+    A[(B, B, StarredB)]
+    >>> A[*b, b, b]
+    A[(StarredB, B, B)]
+    >>> A[b, *b, b]
+    A[(B, StarredB, B)]
+    >>> A[b, b, *b, b]
+    A[(B, B, StarredB, B)]
+    >>> A[b, *b, b, b]
+    A[(B, StarredB, B, B)]
+    >>> A[A[b, *b, b]]
+    A[A[(B, StarredB, B)]]
+    >>> A[*A[b, *b, b]]
+    A[(B, StarredB, B)]
+    >>> A[b, ...]
+    A[(B, Ellipsis)]
+    >>> A[*A[b, ...]]
+    A[(B, Ellipsis)]
+
+Slices that are supposed to work, starring a list
+
+    >>> l = [1, 2, 3]
+    >>> A[*l]
+    A[(1, 2, 3)]
+    >>> A[*l, 4]
+    A[(1, 2, 3, 4)]
+    >>> A[0, *l]
+    A[(0, 1, 2, 3)]
+    >>> A[1:2, *l]
+    A[(slice(1, 2, None), 1, 2, 3)]
+    >>> repr(A[1:2, *l]) == repr(A[1:2, 1, 2, 3])
+    True
+
+Slices that are supposed to work, starring a tuple
+
+    >>> t = (1, 2, 3)
+    >>> A[*t]
+    A[(1, 2, 3)]
+    >>> A[*t, 4]
+    A[(1, 2, 3, 4)]
+    >>> A[0, *t]
+    A[(0, 1, 2, 3)]
+    >>> A[1:2, *t]
+    A[(slice(1, 2, None), 1, 2, 3)]
+    >>> repr(A[1:2, *t]) == repr(A[1:2, 1, 2, 3])
+    True
+
+Starring an expression (rather than a name) in a slice
+
+    >>> def returns_list():
+    ...     return [1, 2, 3]
+    >>> A[returns_list()]
+    A[[1, 2, 3]]
+    >>> A[returns_list(), 4]
+    A[([1, 2, 3], 4)]
+    >>> A[*returns_list()]
+    A[(1, 2, 3)]
+    >>> A[*returns_list(), 4]
+    A[(1, 2, 3, 4)]
+    >>> A[0, *returns_list()]
+    A[(0, 1, 2, 3)]
+    >>> A[*returns_list(), *returns_list()]
+    A[(1, 2, 3, 1, 2, 3)]
+
+Slices that should fail
+
+    >>> A[:*b]
+    Traceback (most recent call last):
+        ...
+    SyntaxError: invalid syntax
+    >>> A[*b:]
+    Traceback (most recent call last):
+        ...
+    SyntaxError: invalid syntax
+    >>> A[*b:*b]
+    Traceback (most recent call last):
+        ...
+    SyntaxError: invalid syntax
+    >>> A[**b]
+    Traceback (most recent call last):
+        ...
+    SyntaxError: invalid syntax
+
+*args annotated as starred expression
+
+    >>> def f1(*args: *b): pass
+    >>> f1.__annotations__
+    {'args': StarredB}
+
+    >>> def f2(*args: *b, arg1): pass
+    >>> f2.__annotations__
+    {'args': StarredB}
+
+    >>> def f3(*args: *b, arg1: int): pass
+    >>> f3.__annotations__
+    {'args': StarredB, 'arg1': <class 'int'>}
+
+    >>> def f4(*args: *b, arg1: int = 2): pass
+    >>> f4.__annotations__
+    {'args': StarredB, 'arg1': <class 'int'>}
+
+Other uses of starred expressions as annotations should fail
+
+    >>> def f6(x: *b): pass
+    Traceback (most recent call last):
+        ...
+    SyntaxError: invalid syntax
+    >>> x: *b
+    Traceback (most recent call last):
+        ...
+    SyntaxError: invalid syntax
+
+"""
+
+__test__ = {'doctests' : doctests}
+
+def test_main(verbose=False):
+    from test import support
+    from test import test_pep646
+    support.run_doctest(test_pep646, verbose)
+
+if __name__ == "__main__":
+    test_main(verbose=True)