Adding a diff to see what is different in module file

Author: shatakshiiii

tests/units/test_add.py

@@ -550,6 +550,15 @@ def mock_update_galaxy_dependency() -> None:
     expected_file = tmp_path / expected_file_path
     effective_file = FIXTURES_DIR / "collection" / "testorg" / "testcol" / expected_file_path
     cmp_result = cmp(expected_file, effective_file, shallow=False)
+    if not cmp_result:
+        diff = subprocess.run(
+            f"diff -u {expected_file} {effective_file}",
+            shell=True,
+            capture_output=True,
+            text=True,
+            check=False,
+        )
+        assert False, f"Files are different:\n{diff.stdout}"  # noqa: B011, PT015
     assert cmp_result
 
     # Test conflict handling