Add a context message to tests to know if initial formatting or idempotence failed

Author: NathanLovato

tests/integration_tests.rs

@@ -13,13 +13,15 @@ fn make_whitespace_visible(s: &str) -> String {
         .replace('\n', "↲\n")
 }
 
-fn assert_formatted_eq(result: &str, expected: &str, file_path: &Path) {
+fn assert_formatted_eq(
+    result: &str,
+    expected: &str,
+    file_path: &Path,
+    error_context_message: &str,
+) {
     if result != expected {
-        eprintln!(
-            "\nFormatted output doesn't match expected for {}",
-            file_path.display()
-        );
-        eprintln!("Diff between expected(-) and formatted output(+):");
+        eprintln!("\n{} - {}", error_context_message, file_path.display());
+        eprintln!("Diff between expected(-) and actual output(+):");
         let diff = TextDiff::from_lines(expected, result);
         for change in diff.iter_all_changes() {
             let text = make_whitespace_visible(&change.to_string());
@@ -34,7 +36,7 @@ fn assert_formatted_eq(result: &str, expected: &str, file_path: &Path) {
         eprintln!("{:?}", expected);
         eprintln!("\nGOT (raw):");
         eprintln!("{:?}", result);
-        panic!("Assertion failed");
+        panic!("Assertion failed: {}", error_context_message);
     }
 }
 
@@ -73,12 +75,21 @@ fn test_file_with_config(file_path: &Path, config: &FormatterConfig, check_idemp
     let result = format_gdscript_with_config(&input_content, config)
         .expect(&format!("Failed to format {}", input_path.display()));
 
-    assert_formatted_eq(&result, &expected_content, &input_path);
+    assert_formatted_eq(
+        &result,
+        &expected_content,
+        &input_path,
+        "First formatting output doesn't match expected",
+    );
 
     if check_idempotence {
         let second_result = format_gdscript_with_config(&result, config)
             .expect(&format!("Failed to format {}", input_path.display()));
-        eprintln!("Checking idempotence: ");
-        assert_formatted_eq(&second_result, &result, &input_path);
+        assert_formatted_eq(
+            &second_result,
+            &result,
+            &input_path,
+            "Idempotence check failed, formatting a second time gave different results",
+        );
     }
 }