REF/TST: use pytest builtin monkeypatch fixture and remove mock fixture

pandas/conftest.py

@@ -1,6 +1,5 @@
 from datetime import date, time, timedelta
 from decimal import Decimal
-import importlib
 import os
 
 from dateutil.tz import tzlocal, tzutc
@@ -637,20 +636,6 @@ def any_skipna_inferred_dtype(request):
     return inferred_dtype, values
 
 
-@pytest.fixture
-def mock():
-    """
-    Fixture providing the 'mock' module.
-
-    Uses 'unittest.mock' for Python 3. Attempts to import the 3rd party 'mock'
-    package for Python 2, skipping if not present.
-    """
-    if PY3:
-        return importlib.import_module("unittest.mock")
-    else:
-        return pytest.importorskip("mock")
-
-
 @pytest.fixture(params=[getattr(pd.offsets, o) for o in pd.offsets.__all__ if
                         issubclass(getattr(pd.offsets, o), pd.offsets.Tick)])
 def tick_classes(request):

pandas/tests/dtypes/test_inference.py

@@ -197,7 +197,7 @@ def __contains__(self, key):
     assert result is expected
 
 
-def test_is_file_like(mock):
+def test_is_file_like():
     class MockFile(object):
         pass
 
@@ -235,7 +235,6 @@ class MockFile(object):
     # Iterator but no read / write attributes
     data = [1, 2, 3]
     assert not is_file(data)
-    assert not is_file(mock.Mock())
 
 
 @pytest.mark.parametrize(

pandas/tests/io/formats/test_format.py

@@ -305,16 +305,14 @@ def test_repr_non_interactive(self):
             assert not has_truncated_repr(df)
             assert not has_expanded_repr(df)
 
-    def test_repr_truncates_terminal_size(self, mock):
-        # https://github.com/pandas-dev/pandas/issues/21180
-        # TODO: use mock fixutre.
-        # This is being backported, so doing it directly here.
+    def test_repr_truncates_terminal_size(self, monkeypatch):
+        # see gh-21180
 
         terminal_size = (118, 96)
-        p1 = mock.patch('pandas.io.formats.console.get_terminal_size',
-                        return_value=terminal_size)
-        p2 = mock.patch('pandas.io.formats.format.get_terminal_size',
-                        return_value=terminal_size)
+        monkeypatch.setattr('pandas.io.formats.console.get_terminal_size',
+                            lambda: terminal_size)
+        monkeypatch.setattr('pandas.io.formats.format.get_terminal_size',
+                            lambda: terminal_size)
 
         index = range(5)
         columns = pd.MultiIndex.from_tuples([
@@ -323,8 +321,7 @@ def test_repr_truncates_terminal_size(self, mock):
         ])
         df = pd.DataFrame(1, index=index, columns=columns)
 
-        with p1, p2:
-            result = repr(df)
+        result = repr(df)
 
         h1, h2 = result.split('\n')[:2]
         assert 'long' in h1
@@ -334,21 +331,19 @@ def test_repr_truncates_terminal_size(self, mock):
 
         # regular columns
         df2 = pd.DataFrame({"A" * 41: [1, 2], 'B' * 41: [1, 2]})
-        with p1, p2:
-            result = repr(df2)
+        result = repr(df2)
 
         assert df2.columns[0] in result.split('\n')[0]
 
-    def test_repr_truncates_terminal_size_full(self, mock):
+    def test_repr_truncates_terminal_size_full(self, monkeypatch):
         # GH 22984 ensure entire window is filled
         terminal_size = (80, 24)
         df = pd.DataFrame(np.random.rand(1, 7))
-        p1 = mock.patch('pandas.io.formats.console.get_terminal_size',
-                        return_value=terminal_size)
-        p2 = mock.patch('pandas.io.formats.format.get_terminal_size',
-                        return_value=terminal_size)
-        with p1, p2:
-            assert "..." not in str(df)
+        monkeypatch.setattr('pandas.io.formats.console.get_terminal_size',
+                            lambda: terminal_size)
+        monkeypatch.setattr('pandas.io.formats.format.get_terminal_size',
+                            lambda: terminal_size)
+        assert "..." not in str(df)
 
     def test_repr_max_columns_max_rows(self):
         term_width, term_height = get_terminal_size()

pandas/tests/io/parser/test_common.py

@@ -1814,13 +1814,16 @@ class InvalidBuffer(object):
         parser.read_csv(InvalidBuffer())
 
 
-def test_invalid_file_buffer_mock(all_parsers, mock):
+def test_invalid_file_buffer_mock(all_parsers):
     # see gh-15337
     parser = all_parsers
     msg = "Invalid file path or buffer object type"
 
+    class Mock():
+        pass
+
     with pytest.raises(ValueError, match=msg):
-        parser.read_csv(mock.Mock())
+        parser.read_csv(Mock())
 
 
 def test_valid_file_buffer_seems_invalid(all_parsers):

pandas/tests/io/test_gcs.py

@@ -17,43 +17,51 @@ def test_is_gcs_url():
 
 
 @td.skip_if_no('gcsfs')
-def test_read_csv_gcs(mock):
+def test_read_csv_gcs(monkeypatch):
     df1 = DataFrame({'int': [1, 3], 'float': [2.0, np.nan], 'str': ['t', 's'],
                      'dt': date_range('2018-06-18', periods=2)})
-    with mock.patch('gcsfs.GCSFileSystem') as MockFileSystem:
-        instance = MockFileSystem.return_value
-        instance.open.return_value = StringIO(df1.to_csv(index=False))
-        df2 = read_csv('gs://test/test.csv', parse_dates=['dt'])
+
+    class MockGCSFileSystem():
+        def open(*args):
+            return StringIO(df1.to_csv(index=False))
+
+    monkeypatch.setattr('gcsfs.GCSFileSystem', MockGCSFileSystem)
+    df2 = read_csv('gs://test/test.csv', parse_dates=['dt'])
 
     assert_frame_equal(df1, df2)
 
 
 @td.skip_if_no('gcsfs')
-def test_to_csv_gcs(mock):
+def test_to_csv_gcs(monkeypatch):
     df1 = DataFrame({'int': [1, 3], 'float': [2.0, np.nan], 'str': ['t', 's'],
                      'dt': date_range('2018-06-18', periods=2)})
-    with mock.patch('gcsfs.GCSFileSystem') as MockFileSystem:
-        s = StringIO()
-        instance = MockFileSystem.return_value
-        instance.open.return_value = s
+    s = StringIO()
+
+    class MockGCSFileSystem():
+        def open(*args):
+            return s
 
-        df1.to_csv('gs://test/test.csv', index=True)
-        df2 = read_csv(StringIO(s.getvalue()), parse_dates=['dt'], index_col=0)
+    monkeypatch.setattr('gcsfs.GCSFileSystem', MockGCSFileSystem)
+    df1.to_csv('gs://test/test.csv', index=True)
+    df2 = read_csv(StringIO(s.getvalue()), parse_dates=['dt'], index_col=0)
 
     assert_frame_equal(df1, df2)
 
 
 @td.skip_if_no('gcsfs')
-def test_gcs_get_filepath_or_buffer(mock):
+def test_gcs_get_filepath_or_buffer(monkeypatch):
     df1 = DataFrame({'int': [1, 3], 'float': [2.0, np.nan], 'str': ['t', 's'],
                      'dt': date_range('2018-06-18', periods=2)})
-    with mock.patch('pandas.io.gcs.get_filepath_or_buffer') as MockGetFilepath:
-        MockGetFilepath.return_value = (StringIO(df1.to_csv(index=False)),
-                                        None, None, False)
-        df2 = read_csv('gs://test/test.csv', parse_dates=['dt'])
+
+    def mock_get_filepath_or_buffer(*args, **kwargs):
+        return (StringIO(df1.to_csv(index=False)),
+                None, None, False)
+
+    monkeypatch.setattr('pandas.io.gcs.get_filepath_or_buffer',
+                        mock_get_filepath_or_buffer)
+    df2 = read_csv('gs://test/test.csv', parse_dates=['dt'])
 
     assert_frame_equal(df1, df2)
-    assert MockGetFilepath.called
 
 
 @pytest.mark.skipif(td.safe_import('gcsfs'),

pandas/tests/plotting/test_frame.py

@@ -2988,21 +2988,21 @@ def test_secondary_axis_font_size(self, method):
         self._check_ticks_props(axes=ax.right_ax,
                                 ylabelsize=fontsize)
 
-    def test_misc_bindings(self, mock):
+    def test_misc_bindings(self, monkeypatch):
         df = pd.DataFrame(randn(10, 10), columns=list('abcdefghij'))
-        p1 = mock.patch('pandas.plotting._misc.scatter_matrix',
-                        return_value=2)
-        p2 = mock.patch('pandas.plotting._misc.andrews_curves',
-                        return_value=2)
-        p3 = mock.patch('pandas.plotting._misc.parallel_coordinates',
-                        return_value=2)
-        p4 = mock.patch('pandas.plotting._misc.radviz',
-                        return_value=2)
-        with p1, p2, p3, p4:
-            assert df.plot.scatter_matrix() == 2
-            assert df.plot.andrews_curves('a') == 2
-            assert df.plot.parallel_coordinates('a') == 2
-            assert df.plot.radviz('a') == 2
+        monkeypatch.setattr('pandas.plotting._misc.scatter_matrix',
+                            lambda x: 2)
+        monkeypatch.setattr('pandas.plotting._misc.andrews_curves',
+                            lambda x, y: 2)
+        monkeypatch.setattr('pandas.plotting._misc.parallel_coordinates',
+                            lambda x, y: 2)
+        monkeypatch.setattr('pandas.plotting._misc.radviz',
+                            lambda x, y: 2)
+
+        assert df.plot.scatter_matrix() == 2
+        assert df.plot.andrews_curves('a') == 2
+        assert df.plot.parallel_coordinates('a') == 2
+        assert df.plot.radviz('a') == 2
 
 
 def _generate_4_axes_via_gridspec():

pandas/tests/plotting/test_series.py

@@ -878,18 +878,18 @@ def test_custom_business_day_freq(self):
 
         _check_plot_works(s.plot)
 
-    def test_misc_bindings(self, mock):
+    def test_misc_bindings(self, monkeypatch):
         s = Series(randn(10))
-        p1 = mock.patch('pandas.plotting._misc.lag_plot',
-                        return_value=2)
-        p2 = mock.patch('pandas.plotting._misc.autocorrelation_plot',
-                        return_value=2)
-        p3 = mock.patch('pandas.plotting._misc.bootstrap_plot',
-                        return_value=2)
-        with p1, p2, p3:
-            assert s.plot.lag() == 2
-            assert s.plot.autocorrelation() == 2
-            assert s.plot.bootstrap() == 2
+        monkeypatch.setattr('pandas.plotting._misc.lag_plot',
+                            lambda x: 2)
+        monkeypatch.setattr('pandas.plotting._misc.autocorrelation_plot',
+                            lambda x: 2)
+        monkeypatch.setattr('pandas.plotting._misc.bootstrap_plot',
+                            lambda x: 2)
+
+        assert s.plot.lag() == 2
+        assert s.plot.autocorrelation() == 2
+        assert s.plot.bootstrap() == 2
 
     @pytest.mark.xfail
     def test_plot_accessor_updates_on_inplace(self):