TST: Simplify assert_warns in test_io.py

numpy/lib/tests/test_io.py

@@ -1824,16 +1824,11 @@ def test_invalid_raise(self):
             data[10 * i] = "2, 2, 2, 2 2"
         data.insert(0, "a, b, c, d, e")
         mdata = TextIO("\n".join(data))
-        #
+
         kwargs = dict(delimiter=",", dtype=None, names=True)
-        # XXX: is there a better way to get the return value of the
-        # callable in assert_warns ?
-        ret = {}
-
-        def f(_ret={}):
-            _ret['mtest'] = np.genfromtxt(mdata, invalid_raise=False, **kwargs)
-        assert_warns(ConversionWarning, f, _ret=ret)
-        mtest = ret['mtest']
+        def f():
+            return np.genfromtxt(mdata, invalid_raise=False, **kwargs)
+        mtest = assert_warns(ConversionWarning, f)
         assert_equal(len(mtest), 45)
         assert_equal(mtest, np.ones(45, dtype=[(_, int) for _ in 'abcde']))
         #
@@ -1848,16 +1843,12 @@ def test_invalid_raise_with_usecols(self):
             data[10 * i] = "2, 2, 2, 2 2"
         data.insert(0, "a, b, c, d, e")
         mdata = TextIO("\n".join(data))
+
         kwargs = dict(delimiter=",", dtype=None, names=True,
                       invalid_raise=False)
-        # XXX: is there a better way to get the return value of the
-        # callable in assert_warns ?
-        ret = {}
-
-        def f(_ret={}):
-            _ret['mtest'] = np.genfromtxt(mdata, usecols=(0, 4), **kwargs)
-        assert_warns(ConversionWarning, f, _ret=ret)
-        mtest = ret['mtest']
+        def f():
+            return np.genfromtxt(mdata, usecols=(0, 4), **kwargs)
+        mtest = assert_warns(ConversionWarning, f)
         assert_equal(len(mtest), 45)
         assert_equal(mtest, np.ones(45, dtype=[(_, int) for _ in 'ae']))
         #