Updated diff test to use different similarity thresholds

Author: Cesar Velazquez

Diff for: test/test_diff.py

@@ -420,17 +420,17 @@ def test_rename_override(self, rw_dir):
         repo = Repo.init(rw_dir)
         file_a = osp.join(rw_dir, "file_a.txt")
         with open(file_a, "w", encoding='utf-8') as outfile:
-            outfile.write("hello world")
+            outfile.write("hello world\n")
         repo.git.add(Git.polish_url(file_a))
         repo.git.commit(message="Added file_a.txt")
 
         # remove file_a.txt
         repo.git.rm(Git.polish_url(file_a))
 
-        # create and commit file_b.txt
+        # create and commit file_b.txt with similarity index of 52
         file_b = osp.join(rw_dir, "file_b.txt")
         with open(file_b, "w", encoding='utf-8') as outfile:
-            outfile.write("hello world")
+            outfile.write("hello world\nhello world")
         repo.git.add(Git.polish_url(file_b))
         repo.git.commit(message="Removed file_a.txt. Added file_b.txt")
 
@@ -458,3 +458,26 @@ def test_rename_override(self, rw_dir):
         diff = diffs[1]
         self.assertEqual(True, diff.new_file)
         self.assertEqual('file_b.txt', diff.a_path)
+
+        # check diff with high similarity index
+        diffs = commit_b.diff(commit_a, split_single_char_options=False, M='75%')
+        self.assertEqual(2, len(diffs))
+
+        # check fileA.txt deleted
+        diff = diffs[0]
+        self.assertEqual(True, diff.deleted_file)
+        self.assertEqual('file_a.txt', diff.a_path)
+
+        # check fileB.txt added
+        diff = diffs[1]
+        self.assertEqual(True, diff.new_file)
+        self.assertEqual('file_b.txt', diff.a_path)
+
+        # check diff with low similarity index
+        diffs = commit_b.diff(commit_a, split_single_char_options=False, M='40%')
+        self.assertEqual(1, len(diffs))
+        diff = diffs[0]
+        self.assertEqual(True, diff.renamed_file)
+        self.assertEqual('file_a.txt', diff.rename_from)
+        self.assertEqual('file_b.txt', diff.rename_to)
+