Support from_type(Tuple[()])

hypothesis-python/RELEASE.rst

@@ -0,0 +1,4 @@
+RELEASE_TYPE: patch
+
+This patch allows :func:`~hypothesis.strategies.from_type` to handle the
+empty tuple type, :class:`typing.Tuple[()] <python:typing.Tuple>`.

hypothesis-python/src/hypothesis/searchstrategy/types.py

@@ -83,6 +83,8 @@ def from_typing_type(thing):
         if getattr(thing, '__tuple_use_ellipsis__', False) or \
                 len(elem_types) == 2 and elem_types[-1] is Ellipsis:
             return st.lists(st.from_type(elem_types[0])).map(tuple)
+        elif len(elem_types) == 1 and elem_types[0] == ():
+            return st.tuples()  # Empty tuple; see issue #1583
         return st.tuples(*map(st.from_type, elem_types))
     if isinstance(thing, typing.TypeVar):
         if getattr(thing, '__bound__', None) is not None:

hypothesis-python/tests/py3/test_lookup.py

@@ -441,3 +441,9 @@ def test_resolving_recursive_type():
         # https://github.com/HypothesisWorks/hypothesis-python/issues/1074
         assert sys.version_info[:2] == (3, 5)
         pytest.skip('Could not find type hints to resolve')
+
+
+@given(from_type(typing.Tuple[()]))
+def test_resolves_empty_Tuple_issue_1583_regression(ex):
+    # See e.g. https://github.com/python/mypy/commit/71332d58
+    assert ex == ()