Fixed several assertTrue() that were intended to be assertEqual(). (GH-8191)

Fixed also testing the "always" warning filter.
diff --git a/Lib/test/test_tokenize.py b/Lib/test/test_tokenize.py
index f68580c..ff14479 100644
--- a/Lib/test/test_tokenize.py
+++ b/Lib/test/test_tokenize.py
@@ -1360,7 +1360,7 @@
             tokenize_module.detect_encoding = orig_detect_encoding
             tokenize_module._tokenize = orig__tokenize
 
-        self.assertTrue(encoding_used, encoding)
+        self.assertEqual(encoding_used, encoding)
 
     def test_oneline_defs(self):
         buf = []