TST: Remove .ix deprecation warnings (#21148)

Partially addresses gh-21137.

Author: gfyoung

pandas/tests/frame/test_indexing.py

@@ -397,11 +397,13 @@ def test_getitem_setitem_ix_negative_integers(self):
 
         df = DataFrame(np.random.randn(8, 4))
         # ix does label-based indexing when having an integer index
-        with pytest.raises(KeyError):
-            df.ix[[-1]]
+        with catch_warnings(record=True):
+            with pytest.raises(KeyError):
+                df.ix[[-1]]
 
-        with pytest.raises(KeyError):
-            df.ix[:, [-1]]
+        with catch_warnings(record=True):
+            with pytest.raises(KeyError):
+                df.ix[:, [-1]]
 
         # #1942
         a = DataFrame(randn(20, 2), index=[chr(x + 65) for x in range(20)])

pandas/tests/indexing/test_indexing.py

@@ -197,7 +197,7 @@ def test_dups_fancy_indexing(self):
         # List containing only missing label
         dfnu = DataFrame(np.random.randn(5, 3), index=list('AABCD'))
         with pytest.raises(KeyError):
-            dfnu.ix[['E']]
+            dfnu.loc[['E']]
 
         # ToDo: check_index_type can be True after GH 11497