tests/format: Make the compare script more useful

Now it will generate a diff of the expected value and what it actually
got

test cases/format/5 transform/file_compare.py

@@ -1,7 +1,31 @@
 #!/usr/bin/env python3
+# SPDX-License-Identifier: Apache-2.0
+# Copyright © 2024 Intel Corporation
 
+import argparse
 import sys
+import difflib
 
-with open(sys.argv[1], 'r', encoding='utf-8') as f, open(sys.argv[2], 'r', encoding='utf-8') as g:
-    if f.read() != g.read():
-        sys.exit('contents are not equal')
+
+def main() -> int:
+    parser = argparse.ArgumentParser()
+    parser.add_argument('actual', help='The transformed contents')
+    parser.add_argument('expected', help='the contents we expected')
+    args = parser.parse_args()
+
+    with open(args.actual, 'r') as f:
+        actual = f.readlines()
+    with open(args.expected, 'r') as f:
+        expected = f.readlines()
+
+    if actual == expected:
+        return 0
+
+    diff = difflib.ndiff(expected, actual)
+    for line in diff:
+        print(line, file=sys.stderr, end='')
+    return 1
+
+
+if __name__ == "__main__":
+    sys.exit(main())