Update aquery differ to python3

More of #16105

Closes #16152.

PiperOrigin-RevId: 469656094
Change-Id: Ic31b1ed64180fa883263515daaf38efc5ee638bf
diff --git a/tools/aquery_differ/aquery_differ_test.py b/tools/aquery_differ/aquery_differ_test.py
index e98901d..3d156bb 100644
--- a/tools/aquery_differ/aquery_differ_test.py
+++ b/tools/aquery_differ/aquery_differ_test.py
@@ -13,21 +13,16 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import io
 import os
 import unittest
+
 # Do not edit this line. Copybara replaces it with PY2 migration helper.
 from third_party.py import mock
-import six
+
 from src.main.protobuf import analysis_v2_pb2
 from tools.aquery_differ import aquery_differ
 
-# pylint: disable=g-import-not-at-top
-if six.PY2:
-  from cStringIO import StringIO
-else:
-  from io import StringIO
-# pylint: enable=g-import-not-at-top
-
 
 def make_aquery_output(action_objs, artifact_objs, path_fragment_objs):
   action_graph = analysis_v2_pb2.ActionGraphContainer()
@@ -114,7 +109,7 @@
                 "parent_id": 1
             },
         ])
-    mock_stdout = StringIO()
+    mock_stdout = io.StringIO()
     attrs = ["cmdline"]
     with mock.patch("sys.stdout", mock_stdout):
       aquery_differ._aquery_diff(action_graph, action_graph, attrs, "before",
@@ -184,7 +179,7 @@
             },
         ])
 
-    mock_stdout = StringIO()
+    mock_stdout = io.StringIO()
     attrs = ["cmdline"]
     with mock.patch("sys.stdout", mock_stdout):
       aquery_differ._aquery_diff(first, second, attrs, "before", "after")
@@ -264,7 +259,7 @@
     expected_error = ("Aquery output 'before' change contains an action "
                       "that generates the following outputs that aquery "
                       "output 'after' change doesn't:\n{}\n\n".format(baz_path))
-    mock_stdout = StringIO()
+    mock_stdout = io.StringIO()
     attrs = ["cmdline"]
     with mock.patch("sys.stdout", mock_stdout):
       aquery_differ._aquery_diff(first, second, attrs, "before", "after")
@@ -372,7 +367,7 @@
     ])
     attrs = ["cmdline"]
 
-    mock_stdout = StringIO()
+    mock_stdout = io.StringIO()
     with mock.patch("sys.stdout", mock_stdout):
       aquery_differ._aquery_diff(first, second, attrs, "before", "after")
       self.assertIn(expected_error_one, mock_stdout.getvalue())
@@ -464,7 +459,7 @@
     ])
     attrs = ["inputs"]
 
-    mock_stdout = StringIO()
+    mock_stdout = io.StringIO()
     with mock.patch("sys.stdout", mock_stdout):
       aquery_differ._aquery_diff(first, second, attrs, "before", "after")
       self.assertIn(expected_error_one, mock_stdout.getvalue())