From 577bb83da99ea35e5bbf7e9edccf198b3d79403f Mon Sep 17 00:00:00 2001
From: Simon Hawkins <simonjayhawkins@gmail.com>
Date: Tue, 26 Feb 2019 12:52:39 +0000
Subject: [PATCH 1/5] STY: use pytest.raises context manager (indexes)

---
 .../tests/indexes/interval/test_interval.py   | 38 ++++++---
 pandas/tests/indexes/test_base.py             | 32 ++++++--
 pandas/tests/indexes/test_category.py         | 77 +++++++++++--------
 pandas/tests/indexes/test_common.py           | 20 ++++-
 pandas/tests/indexes/test_numeric.py          | 68 +++++++++++-----
 .../indexes/timedeltas/test_arithmetic.py     | 26 +++++--
 .../indexes/timedeltas/test_construction.py   | 11 ++-
 pandas/tests/indexes/timedeltas/test_ops.py   |  4 +-
 .../timedeltas/test_partial_slicing.py        |  4 +-
 .../indexes/timedeltas/test_timedelta.py      | 10 ++-
 pandas/tests/indexes/timedeltas/test_tools.py | 18 +++--
 11 files changed, 216 insertions(+), 92 deletions(-)

diff --git a/pandas/tests/indexes/interval/test_interval.py b/pandas/tests/indexes/interval/test_interval.py
index e4f25ff143273..ba451da10573a 100644
--- a/pandas/tests/indexes/interval/test_interval.py
+++ b/pandas/tests/indexes/interval/test_interval.py
@@ -403,13 +403,16 @@ def test_get_item(self, closed):
 
     # To be removed, replaced by test_interval_new.py (see #16316, #16386)
     def test_get_loc_value(self):
-        pytest.raises(KeyError, self.index.get_loc, 0)
+        with pytest.raises(KeyError, match="^0$"):
+            self.index.get_loc(0)
         assert self.index.get_loc(0.5) == 0
         assert self.index.get_loc(1) == 0
         assert self.index.get_loc(1.5) == 1
         assert self.index.get_loc(2) == 1
-        pytest.raises(KeyError, self.index.get_loc, -1)
-        pytest.raises(KeyError, self.index.get_loc, 3)
+        with pytest.raises(KeyError, match="^-1$"):
+            self.index.get_loc(-1)
+        with pytest.raises(KeyError, match="^3$"):
+            self.index.get_loc(3)
 
         idx = IntervalIndex.from_tuples([(0, 2), (1, 3)])
         assert idx.get_loc(0.5) == 0
@@ -419,10 +422,12 @@ def test_get_loc_value(self):
         tm.assert_numpy_array_equal(np.sort(idx.get_loc(2)),
                                     np.array([0, 1], dtype='intp'))
         assert idx.get_loc(3) == 1
-        pytest.raises(KeyError, idx.get_loc, 3.5)
+        with pytest.raises(KeyError, match=r"^3\.5$"):
+            idx.get_loc(3.5)
 
         idx = IntervalIndex.from_arrays([0, 2], [1, 3])
-        pytest.raises(KeyError, idx.get_loc, 1.5)
+        with pytest.raises(KeyError, match=r"^1\.5$"):
+            idx.get_loc(1.5)
 
     # To be removed, replaced by test_interval_new.py (see #16316, #16386)
     def slice_locs_cases(self, breaks):
@@ -486,7 +491,9 @@ def test_slice_locs_decreasing_float64(self):
     # To be removed, replaced by test_interval_new.py (see #16316, #16386)
     def test_slice_locs_fails(self):
         index = IntervalIndex.from_tuples([(1, 2), (0, 1), (2, 3)])
-        with pytest.raises(KeyError):
+        msg = ("'can only get slices from an IntervalIndex if bounds are"
+               " non-overlapping and all monotonic increasing or decreasing'")
+        with pytest.raises(KeyError, match=msg):
             index.slice_locs(1, 2)
 
     # To be removed, replaced by test_interval_new.py (see #16316, #16386)
@@ -494,9 +501,12 @@ def test_get_loc_interval(self):
         assert self.index.get_loc(Interval(0, 1)) == 0
         assert self.index.get_loc(Interval(0, 0.5)) == 0
         assert self.index.get_loc(Interval(0, 1, 'left')) == 0
-        pytest.raises(KeyError, self.index.get_loc, Interval(2, 3))
-        pytest.raises(KeyError, self.index.get_loc,
-                      Interval(-1, 0, 'left'))
+        msg = r"Interval\(2, 3, closed='right'\)"
+        with pytest.raises(KeyError, match=msg):
+            self.index.get_loc(Interval(2, 3))
+        msg = r"Interval\(-1, 0, closed='left'\)"
+        with pytest.raises(KeyError, match=msg):
+            self.index.get_loc(Interval(-1, 0, 'left'))
 
     # Make consistent with test_interval_new.py (see #16316, #16386)
     @pytest.mark.parametrize('item', [3, Interval(1, 4)])
@@ -981,9 +991,11 @@ def test_comparison(self):
             self.index > 0
         with pytest.raises(TypeError, match='unorderable types'):
             self.index <= 0
-        with pytest.raises(TypeError):
+        msg = r"unorderable types: Interval\(\) > int\(\)"
+        with pytest.raises(TypeError, match=msg):
             self.index > np.arange(2)
-        with pytest.raises(ValueError):
+        msg = "Lengths must match to compare"
+        with pytest.raises(ValueError, match=msg):
             self.index > np.arange(3)
 
     def test_missing_values(self, closed):
@@ -993,7 +1005,9 @@ def test_missing_values(self, closed):
             [np.nan, 0, 1], [np.nan, 1, 2], closed=closed)
         assert idx.equals(idx2)
 
-        with pytest.raises(ValueError):
+        msg = ("missing values must be missing in the same location both left"
+               " and right sides")
+        with pytest.raises(ValueError, match=msg):
             IntervalIndex.from_arrays(
                 [np.nan, 0, 1], np.array([0, 1, 2]), closed=closed)
 
diff --git a/pandas/tests/indexes/test_base.py b/pandas/tests/indexes/test_base.py
index 8415bab802239..0508e66d5b9b3 100644
--- a/pandas/tests/indexes/test_base.py
+++ b/pandas/tests/indexes/test_base.py
@@ -4,6 +4,7 @@
 from datetime import datetime, timedelta
 import math
 import operator
+import re
 import sys
 
 import numpy as np
@@ -107,7 +108,10 @@ def test_constructor_copy(self):
 
     def test_constructor_corner(self):
         # corner case
-        pytest.raises(TypeError, Index, 0)
+        msg = (r"Index\(\.\.\.\) must be called with a collection of some"
+               " kind, 0 was passed")
+        with pytest.raises(TypeError, match=msg):
+            Index(0)
 
     @pytest.mark.parametrize("index_vals", [
         [('A', 1), 'B'], ['B', ('A', 1)]])
@@ -496,7 +500,12 @@ def test_view_with_args(self):
             ind = self.indices[i]
 
             # with arguments
-            pytest.raises(TypeError, lambda: ind.view('i8'))
+            if i == 'catIndex':
+                msg = r"view\(\) takes 1 positional argument but 2 were given"
+            else:
+                msg = "Cannot change data-type for object array"
+            with pytest.raises(TypeError, match=msg):
+                ind.view('i8')
 
         # these are ok
         for i in list(set(self.indices.keys()) - set(restricted)):
@@ -565,7 +574,8 @@ def test_delete(self, pos, expected):
 
     def test_delete_raises(self):
         index = Index(['a', 'b', 'c', 'd'], name='index')
-        with pytest.raises((IndexError, ValueError)):
+        msg = "index 5 is out of bounds for axis 0 with size 4"
+        with pytest.raises((IndexError, ValueError), match=msg):
             # either depending on numpy version
             index.delete(5)
 
@@ -683,7 +693,9 @@ def test_empty_fancy_raises(self, attr):
 
         assert index[[]].identical(empty_index)
         # np.ndarray only accepts ndarray of int & bool dtypes, so should Index
-        pytest.raises(IndexError, index.__getitem__, empty_farr)
+        msg = r"arrays used as indices must be of integer \(or boolean\) type"
+        with pytest.raises(IndexError, match=msg):
+            index[empty_farr]
 
     @pytest.mark.parametrize("sort", [None, False])
     def test_intersection(self, sort):
@@ -1426,13 +1438,14 @@ def test_get_indexer_strings(self, method, expected):
     def test_get_indexer_strings_raises(self):
         index = pd.Index(['b', 'c'])
 
-        with pytest.raises(TypeError):
+        msg = r"unsupported operand type\(s\) for -: 'str' and 'str'"
+        with pytest.raises(TypeError, match=msg):
             index.get_indexer(['a', 'b', 'c', 'd'], method='nearest')
 
-        with pytest.raises(TypeError):
+        with pytest.raises(TypeError, match=msg):
             index.get_indexer(['a', 'b', 'c', 'd'], method='pad', tolerance=2)
 
-        with pytest.raises(TypeError):
+        with pytest.raises(TypeError, match=msg):
             index.get_indexer(['a', 'b', 'c', 'd'], method='pad',
                               tolerance=[2, 2, 2, 2])
 
@@ -1685,8 +1698,11 @@ def test_drop_tuple(self, values, to_drop):
             tm.assert_index_equal(result, expected)
 
         removed = index.drop(to_drop[1])
+        msg = r"\"\[{}\] not found in axis\"".format(
+            re.escape(to_drop[1].__repr__()))
         for drop_me in to_drop[1], [to_drop[1]]:
-            pytest.raises(KeyError, removed.drop, drop_me)
+            with pytest.raises(KeyError, match=msg):
+                removed.drop(drop_me)
 
     @pytest.mark.parametrize("method,expected,sort", [
         ('intersection', np.array([(1, 'A'), (2, 'A'), (1, 'B'), (2, 'B')],
diff --git a/pandas/tests/indexes/test_category.py b/pandas/tests/indexes/test_category.py
index d889135160ae2..95fac2f6ae05b 100644
--- a/pandas/tests/indexes/test_category.py
+++ b/pandas/tests/indexes/test_category.py
@@ -181,18 +181,21 @@ def test_create_categorical(self):
         expected = Categorical(['a', 'b', 'c'])
         tm.assert_categorical_equal(result, expected)
 
-    def test_disallow_set_ops(self):
-
+    @pytest.mark.parametrize('func,op_name', [
+        (lambda idx: idx - idx, '__sub__'),
+        (lambda idx: idx + idx, '__add__'),
+        (lambda idx: idx - ['a', 'b'], '__sub__'),
+        (lambda idx: idx + ['a', 'b'], '__add__'),
+        (lambda idx: ['a', 'b'] - idx, '__rsub__'),
+        (lambda idx: ['a', 'b'] + idx, '__radd__'),
+    ])
+    def test_disallow_set_ops(self, func, op_name):
         # GH 10039
         # set ops (+/-) raise TypeError
         idx = pd.Index(pd.Categorical(['a', 'b']))
-
-        pytest.raises(TypeError, lambda: idx - idx)
-        pytest.raises(TypeError, lambda: idx + idx)
-        pytest.raises(TypeError, lambda: idx - ['a', 'b'])
-        pytest.raises(TypeError, lambda: idx + ['a', 'b'])
-        pytest.raises(TypeError, lambda: ['a', 'b'] - idx)
-        pytest.raises(TypeError, lambda: ['a', 'b'] + idx)
+        msg = "cannot perform {} with this index type: CategoricalIndex"
+        with pytest.raises(TypeError, match=msg.format(op_name)):
+            func(idx)
 
     def test_method_delegation(self):
 
@@ -231,8 +234,9 @@ def test_method_delegation(self):
             list('aabbca'), categories=list('cabdef'), ordered=True))
 
         # invalid
-        pytest.raises(ValueError, lambda: ci.set_categories(
-            list('cab'), inplace=True))
+        msg = "cannot use inplace with CategoricalIndex"
+        with pytest.raises(ValueError, match=msg):
+            ci.set_categories(list('cab'), inplace=True)
 
     def test_contains(self):
 
@@ -357,12 +361,11 @@ def test_append(self):
         tm.assert_index_equal(result, ci, exact=True)
 
         # appending with different categories or reordered is not ok
-        pytest.raises(
-            TypeError,
-            lambda: ci.append(ci.values.set_categories(list('abcd'))))
-        pytest.raises(
-            TypeError,
-            lambda: ci.append(ci.values.reorder_categories(list('abc'))))
+        msg = "all inputs must be Index"
+        with pytest.raises(TypeError, match=msg):
+            ci.append(ci.values.set_categories(list('abcd')))
+        with pytest.raises(TypeError, match=msg):
+            ci.append(ci.values.reorder_categories(list('abc')))
 
         # with objects
         result = ci.append(Index(['c', 'a']))
@@ -370,7 +373,9 @@ def test_append(self):
         tm.assert_index_equal(result, expected, exact=True)
 
         # invalid objects
-        pytest.raises(TypeError, lambda: ci.append(Index(['a', 'd'])))
+        msg = "cannot append a non-category item to a CategoricalIndex"
+        with pytest.raises(TypeError, match=msg):
+            ci.append(Index(['a', 'd']))
 
         # GH14298 - if base object is not categorical -> coerce to object
         result = Index(['c', 'a']).append(ci)
@@ -406,7 +411,10 @@ def test_insert(self):
         tm.assert_index_equal(result, expected, exact=True)
 
         # invalid
-        pytest.raises(TypeError, lambda: ci.insert(0, 'd'))
+        msg = ("cannot insert an item into a CategoricalIndex that is not"
+               " already an existing category")
+        with pytest.raises(TypeError, match=msg):
+            ci.insert(0, 'd')
 
         # GH 18295 (test missing)
         expected = CategoricalIndex(['a', np.nan, 'a', 'b', 'c', 'b'])
@@ -633,12 +641,16 @@ def test_get_indexer(self):
             r1 = idx1.get_indexer(idx2)
             assert_almost_equal(r1, np.array([0, 1, 2, -1], dtype=np.intp))
 
-        pytest.raises(NotImplementedError,
-                      lambda: idx2.get_indexer(idx1, method='pad'))
-        pytest.raises(NotImplementedError,
-                      lambda: idx2.get_indexer(idx1, method='backfill'))
-        pytest.raises(NotImplementedError,
-                      lambda: idx2.get_indexer(idx1, method='nearest'))
+        msg = ("method='pad' and method='backfill' not implemented yet for"
+               " CategoricalIndex")
+        with pytest.raises(NotImplementedError, match=msg):
+            idx2.get_indexer(idx1, method='pad')
+        with pytest.raises(NotImplementedError, match=msg):
+            idx2.get_indexer(idx1, method='backfill')
+
+        msg = "method='nearest' not implemented yet for CategoricalIndex"
+        with pytest.raises(NotImplementedError, match=msg):
+            idx2.get_indexer(idx1, method='nearest')
 
     def test_get_loc(self):
         # GH 12531
@@ -776,12 +788,15 @@ def test_equals_categorical(self):
         # invalid comparisons
         with pytest.raises(ValueError, match="Lengths must match"):
             ci1 == Index(['a', 'b', 'c'])
-        pytest.raises(TypeError, lambda: ci1 == ci2)
-        pytest.raises(
-            TypeError, lambda: ci1 == Categorical(ci1.values, ordered=False))
-        pytest.raises(
-            TypeError,
-            lambda: ci1 == Categorical(ci1.values, categories=list('abc')))
+
+        msg = ("categorical index comparisons must have the same categories"
+               " and ordered attributes")
+        with pytest.raises(TypeError, match=msg):
+            ci1 == ci2
+        with pytest.raises(TypeError, match=msg):
+            ci1 == Categorical(ci1.values, ordered=False)
+        with pytest.raises(TypeError, match=msg):
+            ci1 == Categorical(ci1.values, categories=list('abc'))
 
         # tests
         # make sure that we are testing for category inclusion properly
diff --git a/pandas/tests/indexes/test_common.py b/pandas/tests/indexes/test_common.py
index fd356202a8ce5..03448129a48fc 100644
--- a/pandas/tests/indexes/test_common.py
+++ b/pandas/tests/indexes/test_common.py
@@ -3,6 +3,8 @@
 any index subclass. Makes use of the `indices` fixture defined
 in pandas/tests/indexes/conftest.py.
 """
+import re
+
 import numpy as np
 import pytest
 
@@ -189,8 +191,14 @@ def test_unique(self, indices):
             result = indices.unique(level=level)
             tm.assert_index_equal(result, expected)
 
-        for level in 3, 'wrong':
-            pytest.raises((IndexError, KeyError), indices.unique, level=level)
+        msg = "Too many levels: Index has only 1 level, not 4"
+        with pytest.raises(IndexError, match=msg):
+            indices.unique(level=3)
+
+        msg = r"Level wrong must be same as name \({}\)".format(
+            re.escape(indices.name.__repr__()))
+        with pytest.raises(KeyError, match=msg):
+            indices.unique(level='wrong')
 
     def test_get_unique_index(self, indices):
         # MultiIndex tested separately
@@ -239,12 +247,16 @@ def test_get_unique_index(self, indices):
                 tm.assert_index_equal(result, expected)
 
     def test_sort(self, indices):
-        pytest.raises(TypeError, indices.sort)
+        msg = "cannot sort an Index object in-place, use sort_values instead"
+        with pytest.raises(TypeError, match=msg):
+            indices.sort()
 
     def test_mutability(self, indices):
         if not len(indices):
             pytest.skip('Skip check for empty Index')
-        pytest.raises(TypeError, indices.__setitem__, 0, indices[0])
+        msg = "Index does not support mutable operations"
+        with pytest.raises(TypeError, match=msg):
+            indices[0] = indices[0]
 
     def test_view(self, indices):
         assert indices.view().name == indices.name
diff --git a/pandas/tests/indexes/test_numeric.py b/pandas/tests/indexes/test_numeric.py
index a64340c02cd22..a1743ef5a569b 100644
--- a/pandas/tests/indexes/test_numeric.py
+++ b/pandas/tests/indexes/test_numeric.py
@@ -1,6 +1,7 @@
 # -*- coding: utf-8 -*-
 
 from datetime import datetime
+import re
 
 import numpy as np
 import pytest
@@ -10,6 +11,7 @@
 
 import pandas as pd
 from pandas import Float64Index, Index, Int64Index, Series, UInt64Index
+from pandas.api.types import pandas_dtype
 from pandas.tests.indexes.common import Base
 import pandas.util.testing as tm
 
@@ -156,9 +158,18 @@ def test_constructor(self):
     def test_constructor_invalid(self):
 
         # invalid
-        pytest.raises(TypeError, Float64Index, 0.)
-        pytest.raises(TypeError, Float64Index, ['a', 'b', 0.])
-        pytest.raises(TypeError, Float64Index, [Timestamp('20130101')])
+        msg = (r"Float64Index\(\.\.\.\) must be called with a collection of"
+               " some kind, 0.0 was passed")
+        with pytest.raises(TypeError, match=msg):
+            Float64Index(0.)
+        msg = ("String dtype not supported, you may need to explicitly cast to"
+               " a numeric type")
+        with pytest.raises(TypeError, match=msg):
+            Float64Index(['a', 'b', 0.])
+        msg = (r"float\(\) argument must be a string or a number, not"
+               " 'Timestamp'")
+        with pytest.raises(TypeError, match=msg):
+            Float64Index([Timestamp('20130101')])
 
     def test_constructor_coerce(self):
 
@@ -216,12 +227,17 @@ def test_astype(self):
 
         # invalid
         for dtype in ['M8[ns]', 'm8[ns]']:
-            pytest.raises(TypeError, lambda: i.astype(dtype))
+            msg = ("Cannot convert Float64Index to dtype {}; integer values"
+                   " are required for conversion").format(pandas_dtype(dtype))
+            with pytest.raises(TypeError, match=re.escape(msg)):
+                i.astype(dtype)
 
         # GH 13149
         for dtype in ['int16', 'int32', 'int64']:
             i = Float64Index([0, 1.1, np.NAN])
-            pytest.raises(ValueError, lambda: i.astype(dtype))
+            msg = "Cannot convert NA to integer"
+            with pytest.raises(ValueError, match=msg):
+                i.astype(dtype)
 
     def test_type_coercion_fail(self, any_int_dtype):
         # see gh-15832
@@ -275,12 +291,16 @@ def test_get_loc(self):
             assert idx.get_loc(1.1, method) == loc
             assert idx.get_loc(1.1, method, tolerance=0.9) == loc
 
-        pytest.raises(KeyError, idx.get_loc, 'foo')
-        pytest.raises(KeyError, idx.get_loc, 1.5)
-        pytest.raises(KeyError, idx.get_loc, 1.5, method='pad',
-                      tolerance=0.1)
-        pytest.raises(KeyError, idx.get_loc, True)
-        pytest.raises(KeyError, idx.get_loc, False)
+        with pytest.raises(KeyError, match="^'foo'$"):
+            idx.get_loc('foo')
+        with pytest.raises(KeyError, match=r"^1\.5$"):
+            idx.get_loc(1.5)
+        with pytest.raises(KeyError, match=r"^1\.5$"):
+            idx.get_loc(1.5, method='pad', tolerance=0.1)
+        with pytest.raises(KeyError, match="^True$"):
+            idx.get_loc(True)
+        with pytest.raises(KeyError, match="^False$"):
+            idx.get_loc(False)
 
         with pytest.raises(ValueError, match='must be numeric'):
             idx.get_loc(1.4, method='nearest', tolerance='foo')
@@ -310,15 +330,20 @@ def test_get_loc_na(self):
         # not representable by slice
         idx = Float64Index([np.nan, 1, np.nan, np.nan])
         assert idx.get_loc(1) == 1
-        pytest.raises(KeyError, idx.slice_locs, np.nan)
+        msg = "'Cannot get left slice bound for non-unique label: nan"
+        with pytest.raises(KeyError, match=msg):
+            idx.slice_locs(np.nan)
 
     def test_get_loc_missing_nan(self):
         # GH 8569
         idx = Float64Index([1, 2])
         assert idx.get_loc(1) == 0
-        pytest.raises(KeyError, idx.get_loc, 3)
-        pytest.raises(KeyError, idx.get_loc, np.nan)
-        pytest.raises(KeyError, idx.get_loc, [np.nan])
+        with pytest.raises(KeyError, match=r"^3\.0$"):
+            idx.get_loc(3)
+        with pytest.raises(KeyError, match="^nan$"):
+            idx.get_loc(np.nan)
+        with pytest.raises(KeyError, match=r"^\[nan\]$"):
+            idx.get_loc([np.nan])
 
     def test_contains_nans(self):
         i = Float64Index([1.0, 2.0, np.nan])
@@ -499,13 +524,17 @@ def test_union_noncomparable(self):
         tm.assert_index_equal(result, expected)
 
     def test_cant_or_shouldnt_cast(self):
+        msg = ("String dtype not supported, you may need to explicitly cast to"
+               " a numeric type")
         # can't
         data = ['foo', 'bar', 'baz']
-        pytest.raises(TypeError, self._holder, data)
+        with pytest.raises(TypeError, match=msg):
+            self._holder(data)
 
         # shouldn't
         data = ['0', '1', '2']
-        pytest.raises(TypeError, self._holder, data)
+        with pytest.raises(TypeError, match=msg):
+            self._holder(data)
 
     def test_view_index(self):
         self.index.view(Index)
@@ -576,7 +605,10 @@ def test_constructor(self):
         tm.assert_index_equal(index, expected)
 
         # scalar raise Exception
-        pytest.raises(TypeError, Int64Index, 5)
+        msg = (r"Int64Index\(\.\.\.\) must be called with a collection of some"
+               " kind, 5 was passed")
+        with pytest.raises(TypeError, match=msg):
+            Int64Index(5)
 
         # copy
         arr = self.index.values
diff --git a/pandas/tests/indexes/timedeltas/test_arithmetic.py b/pandas/tests/indexes/timedeltas/test_arithmetic.py
index 04977023d7c62..3173252e174ab 100644
--- a/pandas/tests/indexes/timedeltas/test_arithmetic.py
+++ b/pandas/tests/indexes/timedeltas/test_arithmetic.py
@@ -198,20 +198,34 @@ def test_ops_ndarray(self):
         expected = pd.to_timedelta(['2 days']).values
         tm.assert_numpy_array_equal(td + other, expected)
         tm.assert_numpy_array_equal(other + td, expected)
-        pytest.raises(TypeError, lambda: td + np.array([1]))
-        pytest.raises(TypeError, lambda: np.array([1]) + td)
+        msg = r"unsupported operand type\(s\) for \+: 'Timedelta' and 'int'"
+        with pytest.raises(TypeError, match=msg):
+            td + np.array([1])
+        msg = (r"unsupported operand type\(s\) for \+: 'numpy.ndarray' and"
+               " 'Timedelta'")
+        with pytest.raises(TypeError, match=msg):
+            np.array([1]) + td
 
         expected = pd.to_timedelta(['0 days']).values
         tm.assert_numpy_array_equal(td - other, expected)
         tm.assert_numpy_array_equal(-other + td, expected)
-        pytest.raises(TypeError, lambda: td - np.array([1]))
-        pytest.raises(TypeError, lambda: np.array([1]) - td)
+        msg = r"unsupported operand type\(s\) for -: 'Timedelta' and 'int'"
+        with pytest.raises(TypeError, match=msg):
+            td - np.array([1])
+        msg = (r"unsupported operand type\(s\) for -: 'numpy.ndarray' and"
+               " 'Timedelta'")
+        with pytest.raises(TypeError, match=msg):
+            np.array([1]) - td
 
         expected = pd.to_timedelta(['2 days']).values
         tm.assert_numpy_array_equal(td * np.array([2]), expected)
         tm.assert_numpy_array_equal(np.array([2]) * td, expected)
-        pytest.raises(TypeError, lambda: td * other)
-        pytest.raises(TypeError, lambda: other * td)
+        msg = ("ufunc multiply cannot use operands with types"
+               r" dtype\('<m8\[ns\]'\) and dtype\('<m8\[ns\]'\)")
+        with pytest.raises(TypeError, match=msg):
+            td * other
+        with pytest.raises(TypeError, match=msg):
+            other * td
 
         tm.assert_numpy_array_equal(td / other,
                                     np.array([1], dtype=np.float64))
diff --git a/pandas/tests/indexes/timedeltas/test_construction.py b/pandas/tests/indexes/timedeltas/test_construction.py
index 3938d6acad2f0..0028f1e2edad5 100644
--- a/pandas/tests/indexes/timedeltas/test_construction.py
+++ b/pandas/tests/indexes/timedeltas/test_construction.py
@@ -168,10 +168,15 @@ def test_constructor_coverage(self):
         tm.assert_index_equal(from_ints, expected)
 
         # non-conforming freq
-        pytest.raises(ValueError, TimedeltaIndex,
-                      ['1 days', '2 days', '4 days'], freq='D')
+        msg = ("Inferred frequency None from passed values does not conform to"
+               " passed frequency D")
+        with pytest.raises(ValueError, match=msg):
+            TimedeltaIndex(['1 days', '2 days', '4 days'], freq='D')
 
-        pytest.raises(ValueError, timedelta_range, periods=10, freq='D')
+        msg = ("Of the four parameters: start, end, periods, and freq, exactly"
+               " three must be specified")
+        with pytest.raises(ValueError, match=msg):
+            timedelta_range(periods=10, freq='D')
 
     def test_constructor_name(self):
         idx = timedelta_range(start='1 days', periods=1, freq='D', name='TEST')
diff --git a/pandas/tests/indexes/timedeltas/test_ops.py b/pandas/tests/indexes/timedeltas/test_ops.py
index 40377e4362b75..63210f67c2dbd 100644
--- a/pandas/tests/indexes/timedeltas/test_ops.py
+++ b/pandas/tests/indexes/timedeltas/test_ops.py
@@ -71,7 +71,9 @@ def test_unknown_attribute(self):
         tdi = pd.timedelta_range(start=0, periods=10, freq='1s')
         ts = pd.Series(np.random.normal(size=10), index=tdi)
         assert 'foo' not in ts.__dict__.keys()
-        pytest.raises(AttributeError, lambda: ts.foo)
+        msg = "'Series' object has no attribute 'foo'"
+        with pytest.raises(AttributeError, match=msg):
+            ts.foo
 
     def test_order(self):
         # GH 10295
diff --git a/pandas/tests/indexes/timedeltas/test_partial_slicing.py b/pandas/tests/indexes/timedeltas/test_partial_slicing.py
index 62bf2a0b4a1cf..9fce1c9acd488 100644
--- a/pandas/tests/indexes/timedeltas/test_partial_slicing.py
+++ b/pandas/tests/indexes/timedeltas/test_partial_slicing.py
@@ -31,7 +31,9 @@ def test_partial_slice(self):
         result = s['6 days, 23:11:12']
         assert result == s.iloc[133]
 
-        pytest.raises(KeyError, s.__getitem__, '50 days')
+        msg = r"^Timedelta\('50 days 00:00:00'\)$"
+        with pytest.raises(KeyError, match=msg):
+            s['50 days']
 
     def test_partial_slice_high_reso(self):
 
diff --git a/pandas/tests/indexes/timedeltas/test_timedelta.py b/pandas/tests/indexes/timedeltas/test_timedelta.py
index 3cbd9942f9d84..062e1c1e9f46d 100644
--- a/pandas/tests/indexes/timedeltas/test_timedelta.py
+++ b/pandas/tests/indexes/timedeltas/test_timedelta.py
@@ -264,9 +264,13 @@ def test_fields(self):
         tm.assert_index_equal(rng.nanoseconds,
                               Index([456, 456], dtype='int64'))
 
-        pytest.raises(AttributeError, lambda: rng.hours)
-        pytest.raises(AttributeError, lambda: rng.minutes)
-        pytest.raises(AttributeError, lambda: rng.milliseconds)
+        msg = "'TimedeltaIndex' object has no attribute '{}'"
+        with pytest.raises(AttributeError, match=msg.format('hours')):
+            rng.hours
+        with pytest.raises(AttributeError, match=msg.format('minutes')):
+            rng.minutes
+        with pytest.raises(AttributeError, match=msg.format('milliseconds')):
+            rng.milliseconds
 
         # with nat
         s = Series(rng)
diff --git a/pandas/tests/indexes/timedeltas/test_tools.py b/pandas/tests/indexes/timedeltas/test_tools.py
index d211219159233..1702e4ff1bf21 100644
--- a/pandas/tests/indexes/timedeltas/test_tools.py
+++ b/pandas/tests/indexes/timedeltas/test_tools.py
@@ -90,7 +90,7 @@ def conv(v):
         expected = TimedeltaIndex([np.timedelta64(1, 'D')] * 5)
         tm.assert_index_equal(result, expected)
 
-        # Test with lists as input when box=false
+        # Test with lists as input when box=fwithalse
         expected = np.array(np.arange(3) * 1000000000, dtype='timedelta64[ns]')
         result = to_timedelta(range(3), unit='s', box=False)
         tm.assert_numpy_array_equal(expected, result)
@@ -115,14 +115,22 @@ def test_to_timedelta_invalid(self):
             to_timedelta(['foo'], errors='never')
 
         # these will error
-        pytest.raises(ValueError, lambda: to_timedelta([1, 2], unit='foo'))
-        pytest.raises(ValueError, lambda: to_timedelta(1, unit='foo'))
+        msg = "invalid unit abbreviation: foo"
+        with pytest.raises(ValueError, match=msg):
+            to_timedelta([1, 2], unit='foo')
+        with pytest.raises(ValueError, match=msg):
+            to_timedelta(1, unit='foo')
 
         # time not supported ATM
-        pytest.raises(ValueError, lambda: to_timedelta(time(second=1)))
+        msg = ("Value must be Timedelta, string, integer, float, timedelta or"
+               " convertible")
+        with pytest.raises(ValueError, match=msg):
+            to_timedelta(time(second=1))
         assert to_timedelta(time(second=1), errors='coerce') is pd.NaT
 
-        pytest.raises(ValueError, lambda: to_timedelta(['foo', 'bar']))
+        msg = "unit abbreviation w/o a number"
+        with pytest.raises(ValueError, match=msg):
+            to_timedelta(['foo', 'bar'])
         tm.assert_index_equal(TimedeltaIndex([pd.NaT, pd.NaT]),
                               to_timedelta(['foo', 'bar'], errors='coerce'))
 

From 2835ac7681f635e7b9ff7a69104ba0285161b3c3 Mon Sep 17 00:00:00 2001
From: Simon Hawkins <simonjayhawkins@gmail.com>
Date: Tue, 26 Feb 2019 13:46:33 +0000
Subject: [PATCH 2/5] skip py2 ci failures

---
 pandas/tests/indexes/test_base.py    | 3 ++-
 pandas/tests/indexes/test_numeric.py | 3 ++-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/pandas/tests/indexes/test_base.py b/pandas/tests/indexes/test_base.py
index 0508e66d5b9b3..60cb8f9f71f93 100644
--- a/pandas/tests/indexes/test_base.py
+++ b/pandas/tests/indexes/test_base.py
@@ -12,7 +12,7 @@
 
 from pandas._libs.tslib import Timestamp
 from pandas.compat import (
-    PY3, PY35, PY36, StringIO, lrange, lzip, range, text_type, u, zip)
+    PY2, PY3, PY35, PY36, StringIO, lrange, lzip, range, text_type, u, zip)
 from pandas.compat.numpy import np_datetime64_compat
 
 from pandas.core.dtypes.common import is_unsigned_integer_dtype
@@ -491,6 +491,7 @@ def test_constructor_cast(self):
         with pytest.raises(ValueError, match=msg):
             Index(["a", "b", "c"], dtype=float)
 
+    @pytest.mark.skipif(PY2, reason="pytest.raises match regex fails")
     def test_view_with_args(self):
 
         restricted = ['unicodeIndex', 'strIndex', 'catIndex', 'boolIndex',
diff --git a/pandas/tests/indexes/test_numeric.py b/pandas/tests/indexes/test_numeric.py
index a1743ef5a569b..1c974d980cae4 100644
--- a/pandas/tests/indexes/test_numeric.py
+++ b/pandas/tests/indexes/test_numeric.py
@@ -7,7 +7,7 @@
 import pytest
 
 from pandas._libs.tslibs import Timestamp
-from pandas.compat import range
+from pandas.compat import PY2, range
 
 import pandas as pd
 from pandas import Float64Index, Index, Int64Index, Series, UInt64Index
@@ -155,6 +155,7 @@ def test_constructor(self):
         result = Index(np.array([np.nan]))
         assert pd.isna(result.values).all()
 
+    @pytest.mark.skipif(PY2, reason="pytest.raises match regex fails")
     def test_constructor_invalid(self):
 
         # invalid

From 8135de89f29bd4b1865421eddd2e62ee58fe3df0 Mon Sep 17 00:00:00 2001
From: Simon Hawkins <simonjayhawkins@gmail.com>
Date: Wed, 27 Feb 2019 19:45:50 +0000
Subject: [PATCH 3/5] fix typo and regex

---
 pandas/tests/indexes/test_numeric.py          | 2 +-
 pandas/tests/indexes/timedeltas/test_tools.py | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/pandas/tests/indexes/test_numeric.py b/pandas/tests/indexes/test_numeric.py
index 1c974d980cae4..26413f4519eff 100644
--- a/pandas/tests/indexes/test_numeric.py
+++ b/pandas/tests/indexes/test_numeric.py
@@ -160,7 +160,7 @@ def test_constructor_invalid(self):
 
         # invalid
         msg = (r"Float64Index\(\.\.\.\) must be called with a collection of"
-               " some kind, 0.0 was passed")
+               r" some kind, 0\.0 was passed")
         with pytest.raises(TypeError, match=msg):
             Float64Index(0.)
         msg = ("String dtype not supported, you may need to explicitly cast to"
diff --git a/pandas/tests/indexes/timedeltas/test_tools.py b/pandas/tests/indexes/timedeltas/test_tools.py
index 1702e4ff1bf21..58482a174dfd1 100644
--- a/pandas/tests/indexes/timedeltas/test_tools.py
+++ b/pandas/tests/indexes/timedeltas/test_tools.py
@@ -90,7 +90,7 @@ def conv(v):
         expected = TimedeltaIndex([np.timedelta64(1, 'D')] * 5)
         tm.assert_index_equal(result, expected)
 
-        # Test with lists as input when box=fwithalse
+        # Test with lists as input when box=false
         expected = np.array(np.arange(3) * 1000000000, dtype='timedelta64[ns]')
         result = to_timedelta(range(3), unit='s', box=False)
         tm.assert_numpy_array_equal(expected, result)

From 5c7e0242ff66ab5e56e00981793218befb5d83ff Mon Sep 17 00:00:00 2001
From: Simon Hawkins <simonjayhawkins@gmail.com>
Date: Thu, 28 Feb 2019 09:59:32 +0000
Subject: [PATCH 4/5] xfail catIndex, remove py2 skip

---
 pandas/tests/indexes/test_base.py | 29 ++++++++++++-----------------
 1 file changed, 12 insertions(+), 17 deletions(-)

diff --git a/pandas/tests/indexes/test_base.py b/pandas/tests/indexes/test_base.py
index 60cb8f9f71f93..d210e122da985 100644
--- a/pandas/tests/indexes/test_base.py
+++ b/pandas/tests/indexes/test_base.py
@@ -12,7 +12,7 @@
 
 from pandas._libs.tslib import Timestamp
 from pandas.compat import (
-    PY2, PY3, PY35, PY36, StringIO, lrange, lzip, range, text_type, u, zip)
+    PY3, PY35, PY36, StringIO, lrange, lzip, range, text_type, u, zip)
 from pandas.compat.numpy import np_datetime64_compat
 
 from pandas.core.dtypes.common import is_unsigned_integer_dtype
@@ -491,28 +491,23 @@ def test_constructor_cast(self):
         with pytest.raises(ValueError, match=msg):
             Index(["a", "b", "c"], dtype=float)
 
-    @pytest.mark.skipif(PY2, reason="pytest.raises match regex fails")
     def test_view_with_args(self):
-
         restricted = ['unicodeIndex', 'strIndex', 'catIndex', 'boolIndex',
                       'empty']
-
-        for i in restricted:
-            ind = self.indices[i]
-
-            # with arguments
-            if i == 'catIndex':
-                msg = r"view\(\) takes 1 positional argument but 2 were given"
-            else:
-                msg = "Cannot change data-type for object array"
-            with pytest.raises(TypeError, match=msg):
-                ind.view('i8')
-
-        # these are ok
         for i in list(set(self.indices.keys()) - set(restricted)):
             ind = self.indices[i]
+            ind.view('i8')
 
-            # with arguments
+    @pytest.mark.parametrize('index_type', [
+        'unicodeIndex',
+        'strIndex',
+        pytest.param('catIndex', marks=pytest.mark.xfail(reason="gh-25464")),
+        'boolIndex',
+        'empty'])
+    def test_view_with_args_object_array_raises(self, index_type):
+        ind = self.indices[index_type]
+        msg = "Cannot change data-type for object array"
+        with pytest.raises(TypeError, match=msg):
             ind.view('i8')
 
     def test_astype(self):

From 3c0f7d392842f7b463a0e302f973f50d30fd600c Mon Sep 17 00:00:00 2001
From: Simon Hawkins <simonjayhawkins@gmail.com>
Date: Thu, 28 Feb 2019 10:36:37 +0000
Subject: [PATCH 5/5] change test_delete_raises expected_exception

---
 pandas/tests/indexes/test_base.py | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/pandas/tests/indexes/test_base.py b/pandas/tests/indexes/test_base.py
index d210e122da985..26dcf7d6bc234 100644
--- a/pandas/tests/indexes/test_base.py
+++ b/pandas/tests/indexes/test_base.py
@@ -571,8 +571,7 @@ def test_delete(self, pos, expected):
     def test_delete_raises(self):
         index = Index(['a', 'b', 'c', 'd'], name='index')
         msg = "index 5 is out of bounds for axis 0 with size 4"
-        with pytest.raises((IndexError, ValueError), match=msg):
-            # either depending on numpy version
+        with pytest.raises(IndexError, match=msg):
             index.delete(5)
 
     def test_identical(self):