TST: add messages to pytest.raises

pandas/tests/arrays/boolean/test_function.py

@@ -54,7 +54,8 @@ def test_ufuncs_binary(ufunc):
     tm.assert_extension_array_equal(result, expected)
 
     # not handled types
-    with pytest.raises(TypeError):
+    msg = r"operand type\(s\) all returned NotImplemented from __array_ufunc__"
+    with pytest.raises(TypeError, match=msg):
         ufunc(a, "test")
 
 
@@ -76,7 +77,8 @@ def test_ufuncs_unary(ufunc):
 @pytest.mark.parametrize("values", [[True, False], [True, None]])
 def test_ufunc_reduce_raises(values):
     a = pd.array(values, dtype="boolean")
-    with pytest.raises(NotImplementedError):
+    msg = "The 'reduce' method is not supported"
+    with pytest.raises(NotImplementedError, match=msg):
         np.add.reduce(a)
 
 

pandas/tests/indexes/ranges/test_constructors.py

@@ -149,9 +149,9 @@ def test_constructor_corner(self):
         tm.assert_index_equal(index, Index(arr))
 
         # non-int raise Exception
-        with pytest.raises(TypeError):
+        with pytest.raises(TypeError, match=r"Wrong type \<class 'str'\>"):
             RangeIndex("1", "10", "1")
-        with pytest.raises(TypeError):
+        with pytest.raises(TypeError, match=r"Wrong type \<class 'float'\>"):
             RangeIndex(1.1, 10.2, 1.3)
 
         # invalid passed type

pandas/tests/indexes/ranges/test_range.py

@@ -117,7 +117,8 @@ def test_delete(self):
         tm.assert_index_equal(result, expected)
         assert result.name == expected.name
 
-        with pytest.raises((IndexError, ValueError)):
+        msg = "index 5 is out of bounds for axis 0 with size 5"
+        with pytest.raises((IndexError, ValueError), match=msg):
             # either depending on numpy version
             result = idx.delete(len(idx))
 

pandas/tests/indexing/multiindex/test_chaining_and_caching.py

@@ -23,7 +23,8 @@ def test_detect_chained_assignment():
     multiind = MultiIndex.from_tuples(tuples, names=["part", "side"])
     zed = DataFrame(events, index=["a", "b"], columns=multiind)
 
-    with pytest.raises(com.SettingWithCopyError):
+    msg = "A value is trying to be set on a copy of a slice from a DataFrame"
+    with pytest.raises(com.SettingWithCopyError, match=msg):
         zed["eyes"]["right"].fillna(value=555, inplace=True)
 
 

pandas/tests/indexing/test_partial.py

@@ -43,10 +43,12 @@ def test_partial_setting(self):
         # iloc/iat raise
         s = s_orig.copy()
 
-        with pytest.raises(IndexError):
+        msg = "iloc cannot enlarge its target object"
+        with pytest.raises(IndexError, match=msg):
             s.iloc[3] = 5.0
 
-        with pytest.raises(IndexError):
+        msg = "index 3 is out of bounds for axis 0 with size 3"
+        with pytest.raises(IndexError, match=msg):
             s.iat[3] = 5.0
 
         # ## frame ##
@@ -58,10 +60,12 @@ def test_partial_setting(self):
         # iloc/iat raise
         df = df_orig.copy()
 
-        with pytest.raises(IndexError):
+        msg = "iloc cannot enlarge its target object"
+        with pytest.raises(IndexError, match=msg):
             df.iloc[4, 2] = 5.0
 
-        with pytest.raises(IndexError):
+        msg = "index 2 is out of bounds for axis 0 with size 2"
+        with pytest.raises(IndexError, match=msg):
             df.iat[4, 2] = 5.0
 
         # row setting where it exists
@@ -162,7 +166,8 @@ def test_partial_setting_mixed_dtype(self):
         # list-like must conform
         df = DataFrame(columns=["A", "B"])
 
-        with pytest.raises(ValueError):
+        msg = "cannot set a row with mismatched columns"
+        with pytest.raises(ValueError, match=msg):
             df.loc[0] = [1, 2, 3]
 
         # TODO: #15657, these are left as object and not coerced
@@ -330,10 +335,12 @@ def test_partial_set_invalid(self):
         df = orig.copy()
 
         # don't allow not string inserts
-        with pytest.raises(TypeError):
+        msg = "cannot insert DatetimeIndex with incompatible label"
+
+        with pytest.raises(TypeError, match=msg):
             df.loc[100.0, :] = df.iloc[0]
 
-        with pytest.raises(TypeError):
+        with pytest.raises(TypeError, match=msg):
             df.loc[100, :] = df.iloc[0]
 
         # allow object conversion here
@@ -375,13 +382,16 @@ def test_partial_set_empty_frame(self):
         # frame
         df = DataFrame()
 
-        with pytest.raises(ValueError):
+        msg = "cannot set a frame with no defined columns"
+
+        with pytest.raises(ValueError, match=msg):
             df.loc[1] = 1
 
-        with pytest.raises(ValueError):
+        with pytest.raises(ValueError, match=msg):
             df.loc[1] = Series([1], index=["foo"])
 
-        with pytest.raises(ValueError):
+        msg = "cannot set a frame with no defined index and a scalar"
+        with pytest.raises(ValueError, match=msg):
             df.loc[:, 1] = 1
 
         # these work as they don't really change

pandas/tests/series/indexing/test_alter_index.py

@@ -283,7 +283,8 @@ def test_reindex_datetimeindexes_tz_naive_and_aware():
     idx = date_range("20131101", tz="America/Chicago", periods=7)
     newidx = date_range("20131103", periods=10, freq="H")
     s = Series(range(7), index=idx)
-    with pytest.raises(TypeError):
+    msg = "Cannot compare tz-naive and tz-aware timestamps"
+    with pytest.raises(TypeError, match=msg):
         s.reindex(newidx, method="ffill")