TST: Use pytest or decorator instead of checking ImportError (#45152)

* TST: Use pytest or decorator instead of checking ImportError

* simplify test

Author: mroeschke

pandas/tests/computation/test_compat.py

@@ -9,36 +9,24 @@
 
 
 def test_compat():
-    # test we have compat with our version of nu
+    # test we have compat with our version of numexpr
 
     from pandas.core.computation.check import NUMEXPR_INSTALLED
 
-    try:
-        import numexpr as ne
+    ne = pytest.importorskip("numexpr")
 
-        ver = ne.__version__
-        if Version(ver) < Version(VERSIONS["numexpr"]):
-            assert not NUMEXPR_INSTALLED
-        else:
-            assert NUMEXPR_INSTALLED
-    except ImportError:
-        pytest.skip("not testing numexpr version compat")
+    ver = ne.__version__
+    if Version(ver) < Version(VERSIONS["numexpr"]):
+        assert not NUMEXPR_INSTALLED
+    else:
+        assert NUMEXPR_INSTALLED
 
 
 @pytest.mark.parametrize("engine", ENGINES)
 @pytest.mark.parametrize("parser", expr.PARSERS)
 def test_invalid_numexpr_version(engine, parser):
-    def testit():
-        a, b = 1, 2  # noqa:F841
-        res = pd.eval("a + b", engine=engine, parser=parser)
-        assert res == 3
-
     if engine == "numexpr":
-        try:
-            import numexpr as ne  # noqa:F401
-        except ImportError:
-            pytest.skip("no numexpr")
-        else:
-            testit()
-    else:
-        testit()
+        pytest.importorskip("numexpr")
+    a, b = 1, 2  # noqa:F841
+    res = pd.eval("a + b", engine=engine, parser=parser)
+    assert res == 3

pandas/tests/frame/test_reductions.py

@@ -285,16 +285,11 @@ def test_stat_op_api(self, float_frame, float_string_frame):
         assert_stat_op_api("sem", float_frame, float_string_frame)
         assert_stat_op_api("median", float_frame, float_string_frame)
 
-        try:
-            from scipy.stats import (  # noqa:F401
-                kurtosis,
-                skew,
-            )
-
-            assert_stat_op_api("skew", float_frame, float_string_frame)
-            assert_stat_op_api("kurt", float_frame, float_string_frame)
-        except ImportError:
-            pass
+    @pytest.mark.filterwarnings("ignore:Dropping of nuisance:FutureWarning")
+    @td.skip_if_no_scipy
+    def test_stat_op_api_skew_kurt(self, float_frame, float_string_frame):
+        assert_stat_op_api("skew", float_frame, float_string_frame)
+        assert_stat_op_api("kurt", float_frame, float_string_frame)
 
     def test_stat_op_calc(self, float_frame_with_na, mixed_float_frame):
         def count(s):
@@ -315,20 +310,6 @@ def std(x):
         def sem(x):
             return np.std(x, ddof=1) / np.sqrt(len(x))
 
-        def skewness(x):
-            from scipy.stats import skew  # noqa:F811
-
-            if len(x) < 3:
-                return np.nan
-            return skew(x, bias=False)
-
-        def kurt(x):
-            from scipy.stats import kurtosis  # noqa:F811
-
-            if len(x) < 4:
-                return np.nan
-            return kurtosis(x, bias=False)
-
         assert_stat_op_calc(
             "nunique",
             nunique,
@@ -371,16 +352,24 @@ def kurt(x):
             check_dates=True,
         )
 
-        try:
-            from scipy import (  # noqa:F401
-                kurtosis,
-                skew,
-            )
+    @td.skip_if_no_scipy
+    def test_stat_op_calc_skew_kurtosis(self, float_frame_with_na):
+        def skewness(x):
+            from scipy.stats import skew
+
+            if len(x) < 3:
+                return np.nan
+            return skew(x, bias=False)
+
+        def kurt(x):
+            from scipy.stats import kurtosis
+
+            if len(x) < 4:
+                return np.nan
+            return kurtosis(x, bias=False)
 
-            assert_stat_op_calc("skew", skewness, float_frame_with_na)
-            assert_stat_op_calc("kurt", kurt, float_frame_with_na)
-        except ImportError:
-            pass
+        assert_stat_op_calc("skew", skewness, float_frame_with_na)
+        assert_stat_op_calc("kurt", kurt, float_frame_with_na)
 
     # TODO: Ensure warning isn't emitted in the first place
     # ignore mean of empty slice and all-NaN