BUG: Fix thinko in assert_deprecated()

assert_deprecated() was recently reworked for stylistic changes (in
0aa32608 "STY: Minor style cleanups in tests and C code.") but made a
thinko - `lst` is already a list of warnings, so we don't need to put
that into [] braces when preparing assertion text. If we do the
reporting breaks:

    In [1]: msg = "4 warnings found but 3 expected."
    In [2]: lst = ['CategoryA', 'CategoryB', 'CategoryC']
    In [3]: n.join([msg] + [lst])
    TypeError   Traceback (most recent call last)
    ----> 1 n.join([msg] + [lst])

    TypeError: sequence item 1: expected string, list found

Fix it.

Cc: Charles Harris <charlesr.harris@gmail.com>

1 files changed, 14 insertions, 1 deletions

diff --git a/numpy/core/tests/test_deprecations.py b/numpy/core/tests/test_deprecations.py
index 8f7e55d91..bfbe27e1b 100644
--- a/numpy/core/tests/test_deprecations.py
+++ b/numpy/core/tests/test_deprecations.py
@@ -89,7 +89,7 @@ class _DeprecationTestCase(object):
         if num is not None and num_found != num:
             msg = "%i warnings found but %i expected." % (len(self.log), num)
             lst = [w.category for w in self.log]
-            raise AssertionError("\n".join([msg] + [lst]))
+            raise AssertionError("\n".join([msg] + lst))
 
         with warnings.catch_warnings():
             warnings.filterwarnings("error", message=self.message,
@@ -400,5 +400,18 @@ class TestNonCContiguousViewDeprecation(_DeprecationTestCase):
         self.assert_deprecated(np.ones((2,2)).T.view, args=(np.int8,))
 
 
+class TestTestDeprecated(object):
+    def test_assert_deprecated(self):
+        test_case_instance = _DeprecationTestCase()
+        test_case_instance.setUp()
+        assert_raises(AssertionError,
+                      test_case_instance.assert_deprecated,
+                      lambda: None)
+
+        def foo():
+            warnings.warn("foo", category=DeprecationWarning)
+
+        test_case_instance.assert_deprecated(foo)
+
 if __name__ == "__main__":
     run_module_suite()