Add more tests for multi file diff reading and printing

Author: mrnugget

diff/diff_test.go

@@ -737,6 +737,8 @@ func TestParseMultiFileDiffAndPrintMultiFileDiff(t *testing.T) {
 		{filename: "sample_contains_only_added_deleted_files.diff", wantFileDiffs: 3},
 		{filename: "sample_onlyin_line_isnt_a_file_header.diff", wantFileDiffs: 4},
 		{filename: "sample_onlyin_complex_filenames.diff", wantFileDiffs: 3},
+		{filename: "sample_multi_file_minuses_pluses.diff", wantFileDiffs: 2},
+		{filename: "sample_multi_file_without_extended.diff", wantFileDiffs: 2},
 	}
 	for _, test := range tests {
 		diffData, err := ioutil.ReadFile(filepath.Join("testdata", test.filename))

diff/testdata/sample_multi_file_minuses_pluses.diff

@@ -0,0 +1,21 @@
+diff --git a/comment-last-line.sql b/comment-last-line.sql
+index 04a1655..97bd115 100644
+--- a/comment-last-line.sql
++++ b/comment-last-line.sql
+@@ -1,4 +1,4 @@
+ select 1;
++++ invalid SQL comment
+ select 2;
+ select 3;
+--- end of three queries
+diff --git a/query.sql b/query.sql
+index 9537d7b..234ef35 100644
+--- a/query.sql
++++ b/query.sql
+@@ -1,5 +1,4 @@
+ select 1;
+--- this is my query
+ select 2;
+ select 3;
+--- this is the last line
++++ invalid sql comment