Improve pytest quality of life

mypy/state.py

@@ -14,5 +14,7 @@ def strict_optional_set(value: bool) -> Iterator[None]:
     global strict_optional
     saved = strict_optional
     strict_optional = value
-    yield
-    strict_optional = saved
+    try:
+        yield
+    finally:
+        strict_optional = saved

mypy/test/helpers.py

@@ -5,7 +5,7 @@
 import shutil
 import contextlib
 
-from typing import List, Iterable, Dict, Tuple, Callable, Any, Optional, Iterator
+from typing import List, Iterable, Dict, Tuple, Callable, Any, Iterator
 
 from mypy import defaults
 import mypy.api as api
@@ -50,6 +50,7 @@ def assert_string_arrays_equal(expected: List[str], actual: List[str],
 
     Display any differences in a human-readable form.
     """
+    __tracebackhide__ = True
 
     actual = clean_up(actual)
     actual = [line.replace("can't", "cannot") for line in actual]
@@ -326,18 +327,6 @@ def retry_on_error(func: Callable[[], Any], max_wait: float = 1.0) -> None:
                 raise
             time.sleep(wait_time)
 
-# TODO: assert_true and assert_false are redundant - use plain assert
-
-
-def assert_true(b: bool, msg: Optional[str] = None) -> None:
-    if not b:
-        raise AssertionError(msg)
-
-
-def assert_false(b: bool, msg: Optional[str] = None) -> None:
-    if b:
-        raise AssertionError(msg)
-
 
 def good_repr(obj: object) -> str:
     if isinstance(obj, str):
@@ -352,6 +341,7 @@ def good_repr(obj: object) -> str:
 
 
 def assert_equal(a: object, b: object, fmt: str = '{} != {}') -> None:
+    __tracebackhide__ = True
     if a != b:
         raise AssertionError(fmt.format(good_repr(a), good_repr(b)))
 
@@ -364,6 +354,7 @@ def typename(t: type) -> str:
 
 
 def assert_type(typ: type, value: object) -> None:
+    __tracebackhide__ = True
     if type(value) != typ:
         raise AssertionError('Invalid type {}, expected {}'.format(
             typename(type(value)), typename(typ)))

mypy/test/testsubtypes.py

@@ -1,4 +1,4 @@
-from mypy.test.helpers import Suite, assert_true, skip
+from mypy.test.helpers import Suite, skip
 from mypy.nodes import CONTRAVARIANT, INVARIANT, COVARIANT
 from mypy.subtypes import is_subtype
 from mypy.test.typefixture import TypeFixture, InterfaceTypeFixture
@@ -188,10 +188,10 @@ def test_type_callable_subtyping(self) -> None:
     #  * generic function types
 
     def assert_subtype(self, s: Type, t: Type) -> None:
-        assert_true(is_subtype(s, t), '{} not subtype of {}'.format(s, t))
+        assert is_subtype(s, t), '{} not subtype of {}'.format(s, t)
 
     def assert_not_subtype(self, s: Type, t: Type) -> None:
-        assert_true(not is_subtype(s, t), '{} subtype of {}'.format(s, t))
+        assert not is_subtype(s, t), '{} subtype of {}'.format(s, t)
 
     def assert_strict_subtype(self, s: Type, t: Type) -> None:
         self.assert_subtype(s, t)