Add support to display diffs for AsyncMock error messages

src/pytest_mock/plugin.py

@@ -47,6 +47,8 @@ def __init__(self, config):
         self.MagicMock = mock_module.MagicMock
         self.NonCallableMock = mock_module.NonCallableMock
         self.PropertyMock = mock_module.PropertyMock
+        if hasattr(mock_module, "AsyncMock"):
+            self.AsyncMock = mock_module.AsyncMock
         self.call = mock_module.call
         self.ANY = mock_module.ANY
         self.DEFAULT = mock_module.DEFAULT
@@ -275,6 +277,41 @@ def wrap_assert_called(*args, **kwargs):
     assert_wrapper(_mock_module_originals["assert_called"], *args, **kwargs)
 
 
+def wrap_assert_not_awaited(*args, **kwargs):
+    __tracebackhide__ = True
+    assert_wrapper(_mock_module_originals["assert_not_awaited"], *args, **kwargs)
+
+
+def wrap_assert_awaited_with(*args, **kwargs):
+    __tracebackhide__ = True
+    assert_wrapper(_mock_module_originals["assert_awaited_with"], *args, **kwargs)
+
+
+def wrap_assert_awaited_once(*args, **kwargs):
+    __tracebackhide__ = True
+    assert_wrapper(_mock_module_originals["assert_awaited_once"], *args, **kwargs)
+
+
+def wrap_assert_awaited_once_with(*args, **kwargs):
+    __tracebackhide__ = True
+    assert_wrapper(_mock_module_originals["assert_awaited_once_with"], *args, **kwargs)
+
+
+def wrap_assert_has_awaits(*args, **kwargs):
+    __tracebackhide__ = True
+    assert_wrapper(_mock_module_originals["assert_has_awaits"], *args, **kwargs)
+
+
+def wrap_assert_any_await(*args, **kwargs):
+    __tracebackhide__ = True
+    assert_wrapper(_mock_module_originals["assert_any_await"], *args, **kwargs)
+
+
+def wrap_assert_awaited(*args, **kwargs):
+    __tracebackhide__ = True
+    assert_wrapper(_mock_module_originals["assert_awaited"], *args, **kwargs)
+
+
 def wrap_assert_methods(config):
     """
     Wrap assert methods of mock module so we can hide their traceback and
@@ -305,6 +342,25 @@ def wrap_assert_methods(config):
         patcher.start()
         _mock_module_patches.append(patcher)
 
+    async_wrappers = {
+        "assert_awaited": wrap_assert_awaited,
+        "assert_awaited_once": wrap_assert_awaited_once,
+        "assert_awaited_with": wrap_assert_awaited_with,
+        "assert_awaited_once_with": wrap_assert_awaited_once_with,
+        "assert_any_await": wrap_assert_any_await,
+        "assert_has_awaits": wrap_assert_has_awaits,
+        "assert_not_awaited": wrap_assert_not_awaited,
+    }
+    for method, wrapper in async_wrappers.items():
+        try:
+            original = getattr(mock_module.AsyncMock, method)
+        except AttributeError:  # pragma: no cover
+            continue
+        _mock_module_originals[method] = original
+        patcher = mock_module.patch.object(mock_module.AsyncMock, method, wrapper)
+        patcher.start()
+        _mock_module_patches.append(patcher)
+
     if hasattr(config, "add_cleanup"):
         add_cleanup = config.add_cleanup
     else:

tests/test_pytest_mock.py

@@ -708,6 +708,43 @@ def test(mocker):
     result.stdout.fnmatch_lines(expected_lines)
 
 
+@pytest.mark.skipif(
+    sys.version_info < (3, 8), reason="AsyncMock is present on 3.8 and above"
+)
+@pytest.mark.usefixtures("needs_assert_rewrite")
+def test_detailed_introspection_async(testdir):
+    """Check that the "mock_use_standalone" is being used.
+    """
+    testdir.makepyfile(
+        """
+        import pytest
+
+        @pytest.mark.asyncio
+        async def test(mocker):
+            m = mocker.AsyncMock()
+            await m('fo')
+            m.assert_awaited_once_with('', bar=4)
+    """
+    )
+    result = testdir.runpytest("-s")
+    expected_lines = [
+        "*AssertionError: expected await not found.",
+        "*Expected: mock('', bar=4)",
+        "*Actual: mock('fo')",
+        "*pytest introspection follows:*",
+        "*Args:",
+        "*assert ('fo',) == ('',)",
+        "*At index 0 diff: 'fo' != ''*",
+        "*Use -v to get the full diff*",
+        "*Kwargs:*",
+        "*assert {} == {'bar': 4}*",
+        "*Right contains* more item*",
+        "*{'bar': 4}*",
+        "*Use -v to get the full diff*",
+    ]
+    result.stdout.fnmatch_lines(expected_lines)
+
+
 def test_missing_introspection(testdir):
     testdir.makepyfile(
         """