CLN: Clean test moments for expanding (pandas-dev#30566)

Author: charlesdong1991

pandas/tests/window/moments/test_moments_expanding.py

@@ -173,19 +173,24 @@ def test_expanding_corr_pairwise_diff_length(self):
         tm.assert_frame_equal(result3, expected)
         tm.assert_frame_equal(result4, expected)
 
+    @pytest.mark.parametrize("has_min_periods", [True, False])
     @pytest.mark.parametrize(
         "func,static_comp",
         [("sum", np.sum), ("mean", np.mean), ("max", np.max), ("min", np.min)],
         ids=["sum", "mean", "max", "min"],
     )
-    def test_expanding_func(self, func, static_comp):
+    def test_expanding_func(self, func, static_comp, has_min_periods):
         def expanding_func(x, min_periods=1, center=False, axis=0):
             exp = x.expanding(min_periods=min_periods, center=center, axis=axis)
             return getattr(exp, func)()
 
         self._check_expanding(expanding_func, static_comp, preserve_nan=False)
+        self._check_expanding_has_min_periods(
+            expanding_func, static_comp, has_min_periods
+        )
 
-    def test_expanding_apply(self, raw):
+    @pytest.mark.parametrize("has_min_periods", [True, False])
+    def test_expanding_apply(self, raw, has_min_periods):
         def expanding_mean(x, min_periods=1):
 
             exp = x.expanding(min_periods=min_periods)
@@ -195,19 +200,20 @@ def expanding_mean(x, min_periods=1):
         # TODO(jreback), needed to add preserve_nan=False
         # here to make this pass
         self._check_expanding(expanding_mean, np.mean, preserve_nan=False)
+        self._check_expanding_has_min_periods(expanding_mean, np.mean, has_min_periods)
 
+    def test_expanding_apply_empty_series(self, raw):
         ser = Series([], dtype=np.float64)
         tm.assert_series_equal(ser, ser.expanding().apply(lambda x: x.mean(), raw=raw))
 
+    def test_expanding_apply_min_periods_0(self, raw):
         # GH 8080
         s = Series([None, None, None])
         result = s.expanding(min_periods=0).apply(lambda x: len(x), raw=raw)
         expected = Series([1.0, 2.0, 3.0])
         tm.assert_series_equal(result, expected)
 
-    def _check_expanding(
-        self, func, static_comp, has_min_periods=True, preserve_nan=True
-    ):
+    def _check_expanding(self, func, static_comp, preserve_nan=True):
 
         series_result = func(self.series)
         assert isinstance(series_result, Series)
@@ -220,6 +226,7 @@ def _check_expanding(
         if preserve_nan:
             assert result.iloc[self._nan_locs].isna().all()
 
+    def _check_expanding_has_min_periods(self, func, static_comp, has_min_periods):
         ser = Series(randn(50))
 
         if has_min_periods:
@@ -245,17 +252,9 @@ def _check_expanding(
             result = func(ser)
             tm.assert_almost_equal(result.iloc[-1], static_comp(ser[:50]))
 
-    def test_moment_functions_zero_length(self):
-        # GH 8056
-        s = Series(dtype=np.float64)
-        s_expected = s
-        df1 = DataFrame()
-        df1_expected = df1
-        df2 = DataFrame(columns=["a"])
-        df2["a"] = df2["a"].astype("float64")
-        df2_expected = df2
-
-        functions = [
+    @pytest.mark.parametrize(
+        "f",
+        [
             lambda x: x.expanding().count(),
             lambda x: x.expanding(min_periods=5).cov(x, pairwise=False),
             lambda x: x.expanding(min_periods=5).corr(x, pairwise=False),
@@ -271,23 +270,35 @@ def test_moment_functions_zero_length(self):
             lambda x: x.expanding(min_periods=5).median(),
             lambda x: x.expanding(min_periods=5).apply(sum, raw=False),
             lambda x: x.expanding(min_periods=5).apply(sum, raw=True),
-        ]
-        for f in functions:
-            try:
-                s_result = f(s)
-                tm.assert_series_equal(s_result, s_expected)
+        ],
+    )
+    def test_moment_functions_zero_length(self, f):
+        # GH 8056
+        s = Series(dtype=np.float64)
+        s_expected = s
+        df1 = DataFrame()
+        df1_expected = df1
+        df2 = DataFrame(columns=["a"])
+        df2["a"] = df2["a"].astype("float64")
+        df2_expected = df2
 
-                df1_result = f(df1)
-                tm.assert_frame_equal(df1_result, df1_expected)
+        s_result = f(s)
+        tm.assert_series_equal(s_result, s_expected)
 
-                df2_result = f(df2)
-                tm.assert_frame_equal(df2_result, df2_expected)
-            except (ImportError):
+        df1_result = f(df1)
+        tm.assert_frame_equal(df1_result, df1_expected)
 
-                # scipy needed for rolling_window
-                continue
+        df2_result = f(df2)
+        tm.assert_frame_equal(df2_result, df2_expected)
 
-    def test_moment_functions_zero_length_pairwise(self):
+    @pytest.mark.parametrize(
+        "f",
+        [
+            lambda x: (x.expanding(min_periods=5).cov(x, pairwise=True)),
+            lambda x: (x.expanding(min_periods=5).corr(x, pairwise=True)),
+        ],
+    )
+    def test_moment_functions_zero_length_pairwise(self, f):
 
         df1 = DataFrame()
         df2 = DataFrame(columns=Index(["a"], name="foo"), index=Index([], name="bar"))
@@ -303,16 +314,12 @@ def test_moment_functions_zero_length_pairwise(self):
             columns=Index(["a"], name="foo"),
             dtype="float64",
         )
-        functions = [
-            lambda x: (x.expanding(min_periods=5).cov(x, pairwise=True)),
-            lambda x: (x.expanding(min_periods=5).corr(x, pairwise=True)),
-        ]
-        for f in functions:
-            df1_result = f(df1)
-            tm.assert_frame_equal(df1_result, df1_expected)
 
-            df2_result = f(df2)
-            tm.assert_frame_equal(df2_result, df2_expected)
+        df1_result = f(df1)
+        tm.assert_frame_equal(df1_result, df1_expected)
+
+        df2_result = f(df2)
+        tm.assert_frame_equal(df2_result, df2_expected)
 
     @pytest.mark.slow
     @pytest.mark.parametrize("min_periods", [0, 1, 2, 3, 4])