MAINT: Remove uses of the WarningManager class.

WarningManager was a workaround for the lack of the with statement
in Python versions < 2.6. As those versions are no longer supported
it can be removed.

Deprecation notes are added to WarningManager and WarningMessage, but
to avoid a cascade of messages in third party apps, no warnings are
raised at this time, that can be done later.

Closes #3519.

4 files changed, 22 insertions, 39 deletions

diff --git a/numpy/core/tests/test_api.py b/numpy/core/tests/test_api.py
index b94f4772e..41d12a30c 100644
--- a/numpy/core/tests/test_api.py
+++ b/numpy/core/tests/test_api.py
@@ -1,11 +1,10 @@
 from __future__ import division, absolute_import, print_function
 
 import sys
+import warnings
 
 import numpy as np
 from numpy.testing import *
-from numpy.testing.utils import WarningManager
-import warnings
 from numpy.compat import sixu
 
 # Switch between new behaviour when NPY_RELAXED_STRIDES_CHECKING is set.
diff --git a/numpy/core/tests/test_einsum.py b/numpy/core/tests/test_einsum.py
index dd5e9b85d..e7480a269 100644
--- a/numpy/core/tests/test_einsum.py
+++ b/numpy/core/tests/test_einsum.py
@@ -1,12 +1,11 @@
 from __future__ import division, absolute_import, print_function
 
 import sys
+import warnings
 from decimal import Decimal
 
 import numpy as np
 from numpy.testing import *
-from numpy.testing.utils import WarningManager
-import warnings
 
 class TestEinSum(TestCase):
     def test_einsum_errors(self):
@@ -272,9 +271,7 @@ class TestEinSum(TestCase):
             assert_equal(np.einsum(a, [0], b, [1]), np.outer(a, b))
 
         # Suppress the complex warnings for the 'as f8' tests
-        ctx = WarningManager()
-        ctx.__enter__()
-        try:
+        with warnings.catch_warnings():
             warnings.simplefilter('ignore', np.ComplexWarning)
 
             # matvec(a,b) / a.dot(b) where a is matrix, b is vector
@@ -379,8 +376,6 @@ class TestEinSum(TestCase):
                                         dtype='f8', casting='unsafe')
                 assert_equal(c, np.tensordot(a.astype('f8'), b.astype('f8'),
                                         axes=([1,0],[0,1])).astype(dtype))
-        finally:
-            ctx.__exit__()
 
         # logical_and(logical_and(a!=0, b!=0), c!=0)
         a = np.array([1,   3,   -2,   0,   12,  13,   0,   1], dtype=dtype)
diff --git a/numpy/core/tests/test_multiarray.py b/numpy/core/tests/test_multiarray.py
index 232734b84..6cd24a76f 100644
--- a/numpy/core/tests/test_multiarray.py
+++ b/numpy/core/tests/test_multiarray.py
@@ -8,7 +8,6 @@ import warnings
 import numpy as np
 from nose import SkipTest
 from numpy.core import *
-from numpy.testing.utils import WarningManager
 from numpy.compat import asbytes, getexception, strchar, sixu
 from test_print import in_foreign_locale
 from numpy.core.multiarray_tests import (
@@ -958,17 +957,13 @@ class TestMethods(TestCase):
         assert_equal(b.diagonal(0, 2, 1), [[0, 3], [4, 7]])
 
     def test_diagonal_deprecation(self):
-        import warnings
-        from numpy.testing.utils import WarningManager
+
         def collect_warning_types(f, *args, **kwargs):
-            ctx = WarningManager(record=True)
-            warning_log = ctx.__enter__()
-            warnings.simplefilter("always")
-            try:
+            with warnings.catch_warnings(record=True) as log:
+                warnings.simplefilter("always")
                 f(*args, **kwargs)
-            finally:
-                ctx.__exit__()
-            return [w.category for w in warning_log]
+            return [w.category for w in log]
+
         a = np.arange(9).reshape(3, 3)
         # All the different functions raise a warning, but not an error, and
         # 'a' is not modified:
@@ -2028,17 +2023,13 @@ class TestRecord(TestCase):
             assert_raises(ValueError, a.__getitem__, sixu('\u03e0'))
 
     def test_field_names_deprecation(self):
-        import warnings
-        from numpy.testing.utils import WarningManager
+
         def collect_warning_types(f, *args, **kwargs):
-            ctx = WarningManager(record=True)
-            warning_log = ctx.__enter__()
-            warnings.simplefilter("always")
-            try:
+            with warnings.catch_warnings(record=True) as log:
+                warnings.simplefilter("always")
                 f(*args, **kwargs)
-            finally:
-                ctx.__exit__()
-            return [w.category for w in warning_log]
+            return [w.category for w in log]
+
         a = np.zeros((1,), dtype=[('f1', 'i4'),
                                   ('f2', 'i4'),
                                   ('f3', [('sf1', 'i4')])])
@@ -2500,36 +2491,38 @@ class TestStackedNeighborhoodIter(TestCase):
         assert_array_equal(l, r)
 
 class TestWarnings(object):
+
     def test_complex_warning(self):
         x = np.array([1,2])
         y = np.array([1-2j,1+2j])
 
-        warn_ctx = WarningManager()
-        warn_ctx.__enter__()
-        try:
+        with warnings.catch_warnings():
             warnings.simplefilter("error", np.ComplexWarning)
             assert_raises(np.ComplexWarning, x.__setitem__, slice(None), y)
             assert_equal(x, [1,2])
-        finally:
-            warn_ctx.__exit__()
 
 class TestMinScalarType(object):
+
     def test_usigned_shortshort(self):
         dt = np.min_scalar_type(2**8-1)
         wanted = np.dtype('uint8')
         assert_equal(wanted, dt)
+
     def test_usigned_short(self):
         dt = np.min_scalar_type(2**16-1)
         wanted = np.dtype('uint16')
         assert_equal(wanted, dt)
+
     def test_usigned_int(self):
         dt = np.min_scalar_type(2**32-1)
         wanted = np.dtype('uint32')
         assert_equal(wanted, dt)
+
     def test_usigned_longlong(self):
         dt = np.min_scalar_type(2**63-1)
         wanted = np.dtype('uint64')
         assert_equal(wanted, dt)
+
     def test_object(self):
         dt = np.min_scalar_type(2**64)
         wanted = np.dtype('O')
diff --git a/numpy/core/tests/test_regression.py b/numpy/core/tests/test_regression.py
index 492b08cb9..740957215 100644
--- a/numpy/core/tests/test_regression.py
+++ b/numpy/core/tests/test_regression.py
@@ -16,7 +16,7 @@ from numpy.testing import (
         assert_almost_equal, assert_array_equal, assert_array_almost_equal,
         assert_raises, assert_warns, dec
         )
-from numpy.testing.utils import _assert_valid_refcount, WarningManager
+from numpy.testing.utils import _assert_valid_refcount
 from numpy.compat import asbytes, asunicode, asbytes_nested, long, sixu
 
 rlevel = 1
@@ -1545,13 +1545,9 @@ class TestRegression(TestCase):
         for tp in [np.csingle, np.cdouble, np.clongdouble]:
             x = tp(1+2j)
             assert_warns(np.ComplexWarning, float, x)
-            warn_ctx = WarningManager()
-            warn_ctx.__enter__()
-            try:
+            with warnings.catch_warnings():
                 warnings.simplefilter('ignore')
                 assert_equal(float(x), float(x.real))
-            finally:
-                warn_ctx.__exit__()
 
     def test_complex_scalar_complex_cast(self):
         for tp in [np.csingle, np.cdouble, np.clongdouble]: