1 files changed, 157 insertions, 0 deletions
diff --git a/Lib/test/test_unpack_ex.py b/Lib/test/test_unpack_ex.py
new file mode 100644
index 0000000..557e449
--- /dev/null
+++ b/Lib/test/test_unpack_ex.py
@@ -0,0 +1,157 @@
+# Tests for extended unpacking, starred expressions.
+
+doctests = """
+
+Unpack tuple
+
+    >>> t = (1, 2, 3)
+    >>> a, *b, c = t
+    >>> a == 1 and b == [2] and c == 3
+    True
+
+Unpack list
+
+    >>> l = [4, 5, 6]
+    >>> a, *b = l
+    >>> a == 4 and b == [5, 6]
+    True
+
+Unpack implied tuple
+
+    >>> *a, = 7, 8, 9
+    >>> a == [7, 8, 9]
+    True
+
+Unpack string... fun!
+
+    >>> a, *b = 'one'
+    >>> a == 'o' and b == ['n', 'e']
+    True
+
+Unpack long sequence
+
+    >>> a, b, c, *d, e, f, g = range(10)
+    >>> (a, b, c, d, e, f, g) == (0, 1, 2, [3, 4, 5, 6], 7, 8, 9)
+    True
+
+Unpack short sequence
+
+    >>> a, *b, c = (1, 2)
+    >>> a == 1 and c == 2 and b == []
+    True
+
+Unpack generic sequence
+
+    >>> class Seq:
+    ...     def __getitem__(self, i):
+    ...         if i >= 0 and i < 3: return i
+    ...         raise IndexError
+    ...
+    >>> a, *b = Seq()
+    >>> a == 0 and b == [1, 2]
+    True
+
+Unpack in for statement
+
+    >>> for a, *b, c in [(1,2,3), (4,5,6,7)]:
+    ...     print(a, b, c)
+    ...
+    1 [2] 3
+    4 [5, 6] 7
+
+Unpack in list
+
+    >>> [a, *b, c] = range(5)
+    >>> a == 0 and b == [1, 2, 3] and c == 4
+    True
+
+Multiple targets
+
+    >>> a, *b, c = *d, e = range(5)
+    >>> a == 0 and b == [1, 2, 3] and c == 4 and d == [0, 1, 2, 3] and e == 4
+    True
+
+Now for some failures
+
+Unpacking non-sequence
+
+    >>> a, *b = 7
+    Traceback (most recent call last):
+      ...
+    TypeError: 'int' object is not iterable
+
+Unpacking sequence too short
+
+    >>> a, *b, c, d, e = Seq()
+    Traceback (most recent call last):
+      ...
+    ValueError: need more than 3 values to unpack
+
+Unpacking a sequence where the test for too long raises a different kind of
+error
+
+    >>> class BozoError(Exception):
+    ...     pass
+    ...
+    >>> class BadSeq:
+    ...     def __getitem__(self, i):
+    ...         if i >= 0 and i < 3:
+    ...             return i
+    ...         elif i == 3:
+    ...             raise BozoError
+    ...         else:
+    ...             raise IndexError
+    ...
+
+Trigger code while not expecting an IndexError (unpack sequence too long, wrong
+error)
+
+    >>> a, *b, c, d, e = BadSeq()
+    Traceback (most recent call last):
+      ...
+    test.test_unpack_ex.BozoError
+
+Now some general starred expressions (all fail).
+
+    >>> a, *b, c, *d, e = range(10) # doctest:+ELLIPSIS
+    Traceback (most recent call last):
+      ...
+    SyntaxError: two starred expressions in assignment (...)
+
+    >>> [*b, *c] = range(10) # doctest:+ELLIPSIS
+    Traceback (most recent call last):
+      ...
+    SyntaxError: two starred expressions in assignment (...)
+
+    >>> *a = range(10) # doctest:+ELLIPSIS
+    Traceback (most recent call last):
+      ...
+    SyntaxError: starred assignment target must be in a list or tuple (...)
+
+    >>> *a # doctest:+ELLIPSIS
+    Traceback (most recent call last):
+      ...
+    SyntaxError: can use starred expression only as assignment target (...)
+
+    >>> *1 # doctest:+ELLIPSIS
+    Traceback (most recent call last):
+      ...
+    SyntaxError: can use starred expression only as assignment target (...)
+
+    >>> x = *a # doctest:+ELLIPSIS
+    Traceback (most recent call last):
+      ...
+    SyntaxError: can use starred expression only as assignment target (...)
+
+"""
+
+__test__ = {'doctests' : doctests}
+
+def test_main(verbose=False):
+    import sys
+    from test import test_support
+    from test import test_unpack_ex
+    test_support.run_doctest(test_unpack_ex, verbose)
+
+if __name__ == "__main__":
+    test_main(verbose=True)