TST: bare pytest raises

pandas/tests/io/excel/test_readers.py

@@ -426,7 +426,8 @@ def test_reader_dtype(self, read_ext):
         expected["c"] = ["001", "002", "003", "004"]
         tm.assert_frame_equal(actual, expected)
 
-        with pytest.raises(ValueError):
+        msg = "Unable to convert column d to type int64"
+        with pytest.raises(ValueError, match=msg):
             pd.read_excel(basename + read_ext, dtype={"d": "int64"})
 
     @pytest.mark.parametrize(
@@ -822,13 +823,15 @@ def test_excel_old_index_format(self, read_ext):
 
     def test_read_excel_bool_header_arg(self, read_ext):
         # GH 6114
+        msg = "Passing a bool to header is invalid"
         for arg in [True, False]:
-            with pytest.raises(TypeError):
+            with pytest.raises(TypeError, match=msg):
                 pd.read_excel("test1" + read_ext, header=arg)
 
     def test_read_excel_chunksize(self, read_ext):
         # GH 8011
-        with pytest.raises(NotImplementedError):
+        msg = "chunksize keyword of read_excel is not implemented"
+        with pytest.raises(NotImplementedError, match=msg):
             pd.read_excel("test1" + read_ext, chunksize=100)
 
     def test_read_excel_skiprows_list(self, read_ext):

pandas/tests/io/excel/test_writers.py

@@ -330,7 +330,8 @@ def test_excel_sheet_by_name_raise(self, path):
 
         tm.assert_frame_equal(gt, df)
 
-        with pytest.raises(xlrd.XLRDError):
+        msg = "No sheet named <'0'>"
+        with pytest.raises(xlrd.XLRDError, match=msg):
             pd.read_excel(xl, "0")
 
     def test_excel_writer_context_manager(self, frame, path):
@@ -973,7 +974,11 @@ def roundtrip(data, header=True, parser_hdr=0, index=True):
         # This if will be removed once multi-column Excel writing
         # is implemented. For now fixing gh-9794.
         if c_idx_nlevels > 1:
-            with pytest.raises(NotImplementedError):
+            msg = (
+                "Writing to Excel with MultiIndex columns and no index "
+                "\\('index'=False\\) is not yet implemented."
+            )
+            with pytest.raises(NotImplementedError, match=msg):
                 roundtrip(df, use_headers, index=False)
         else:
             res = roundtrip(df, use_headers)

pandas/tests/io/excel/test_xlwt.py

@@ -18,7 +18,12 @@ def test_excel_raise_error_on_multiindex_columns_and_no_index(ext):
         [("site", ""), ("2014", "height"), ("2014", "weight")]
     )
     df = DataFrame(np.random.randn(10, 3), columns=cols)
-    with pytest.raises(NotImplementedError):
+
+    msg = (
+        "Writing to Excel with MultiIndex columns and no index "
+        "\\('index'=False\\) is not yet implemented."
+    )
+    with pytest.raises(NotImplementedError, match=msg):
         with tm.ensure_clean(ext) as path:
             df.to_excel(path, index=False)
 

pandas/tests/io/formats/test_format.py

@@ -1508,7 +1508,8 @@ def test_to_string_specified_header(self):
 
         assert df_s == expected
 
-        with pytest.raises(ValueError):
+        msg = "Writing 2 cols but got 1 aliases"
+        with pytest.raises(ValueError, match=msg):
             df.to_string(header=["X"])
 
     def test_to_string_no_index(self):

pandas/tests/io/formats/test_style.py

@@ -37,7 +37,8 @@ def h(x, foo="bar"):
         ]
 
     def test_init_non_pandas(self):
-        with pytest.raises(TypeError):
+        msg = "``data`` must be a Series or DataFrame"
+        with pytest.raises(TypeError, match=msg):
             Styler([1, 2, 3])
 
     def test_init_series(self):
@@ -1013,7 +1014,8 @@ def test_bar_align_zero_nans(self):
 
     def test_bar_bad_align_raises(self):
         df = pd.DataFrame({"A": [-100, -60, -30, -20]})
-        with pytest.raises(ValueError):
+        msg = "`align` must be one of {'left', 'zero',' mid'}"
+        with pytest.raises(ValueError, match=msg):
             df.style.bar(align="poorly", color=["#d65f5f", "#5fba7d"])
 
     def test_format_with_na_rep(self):
@@ -1082,7 +1084,8 @@ def test_format_non_numeric_na(self):
     def test_format_with_bad_na_rep(self):
         # GH 21527 28358
         df = pd.DataFrame([[None, None], [1.1, 1.2]], columns=["A", "B"])
-        with pytest.raises(TypeError):
+        msg = "Expected a string, got -1 instead"
+        with pytest.raises(TypeError, match=msg):
             df.style.format(None, na_rep=-1)
 
     def test_highlight_null(self, null_color="red"):
@@ -1110,10 +1113,11 @@ def test_highlight_null_subset(self):
 
     def test_nonunique_raises(self):
         df = pd.DataFrame([[1, 2]], columns=["A", "A"])
-        with pytest.raises(ValueError):
+        msg = "style is not supported for non-unique indices."
+        with pytest.raises(ValueError, match=msg):
             df.style
 
-        with pytest.raises(ValueError):
+        with pytest.raises(ValueError, match=msg):
             Styler(df)
 
     def test_caption(self):
@@ -1260,9 +1264,12 @@ def test_display_format(self):
 
     def test_display_format_raises(self):
         df = pd.DataFrame(np.random.randn(2, 2))
-        with pytest.raises(TypeError):
+        msg = "Expected a template string or callable, got 5 instead"
+        with pytest.raises(TypeError, match=msg):
             df.style.format(5)
-        with pytest.raises(TypeError):
+
+        msg = "Expected a template string or callable, got True instead"
+        with pytest.raises(TypeError, match=msg):
             df.style.format(True)
 
     def test_display_set_precision(self):
@@ -1335,35 +1342,39 @@ def test_display_dict(self):
 
     def test_bad_apply_shape(self):
         df = pd.DataFrame([[1, 2], [3, 4]])
-        with pytest.raises(ValueError):
+        msg = "returned the wrong shape"
+        with pytest.raises(ValueError, match=msg):
             df.style._apply(lambda x: "x", subset=pd.IndexSlice[[0, 1], :])
 
-        with pytest.raises(ValueError):
+        with pytest.raises(ValueError, match=msg):
             df.style._apply(lambda x: [""], subset=pd.IndexSlice[[0, 1], :])
 
-        with pytest.raises(ValueError):
+        with pytest.raises(ValueError, match=msg):
             df.style._apply(lambda x: ["", "", "", ""])
 
-        with pytest.raises(ValueError):
+        with pytest.raises(ValueError, match=msg):
             df.style._apply(lambda x: ["", "", ""], subset=1)
 
-        with pytest.raises(ValueError):
+        msg = "Length mismatch: Expected axis has 3 elements"
+        with pytest.raises(ValueError, match=msg):
             df.style._apply(lambda x: ["", "", ""], axis=1)
 
     def test_apply_bad_return(self):
         def f(x):
             return ""
 
         df = pd.DataFrame([[1, 2], [3, 4]])
-        with pytest.raises(TypeError):
+        msg = "must return a DataFrame when passed to `Styler.apply` with axis=None"
+        with pytest.raises(TypeError, match=msg):
             df.style._apply(f, axis=None)
 
     def test_apply_bad_labels(self):
         def f(x):
             return pd.DataFrame(index=[1, 2], columns=["a", "b"])
 
         df = pd.DataFrame([[1, 2], [3, 4]])
-        with pytest.raises(ValueError):
+        msg = "must have identical index and columns as the input"
+        with pytest.raises(ValueError, match=msg):
             df.style._apply(f, axis=None)
 
     def test_get_level_lengths(self):

pandas/tests/io/formats/test_to_latex.py

@@ -664,7 +664,8 @@ def test_to_latex_specified_header(self):
 
         assert withoutescape_result == withoutescape_expected
 
-        with pytest.raises(ValueError):
+        msg = "Writing 2 cols but got 1 aliases"
+        with pytest.raises(ValueError, match=msg):
             df.to_latex(header=["A"])
 
     def test_to_latex_decimal(self, float_frame):