assert: show the diff when deep comparing data with a custom message

Fixes: #48465
nodejs · Sep 4, 2024 · 89cb67f · 89cb67f
1 parent 5949e16
commit 89cb67f
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Showing 2 changed files with 22 additions and 7 deletions.
diff --git a/lib/internal/assert/assertion_error.js b/lib/internal/assert/assertion_error.js
@@ -72,7 +72,7 @@ function inspectValue(val) {
   );
 }
 
-function createErrDiff(actual, expected, operator) {
+function createErrDiff(actual, expected, operator, message = '') {
   let other = '';
   let res = '';
   let end = '';
@@ -184,8 +184,8 @@ function createErrDiff(actual, expected, operator) {
 
   let printedLines = 0;
   let identical = 0;
-  const msg = kReadableOperator[operator] +
-        `\n${colors.green}+ actual${colors.white} ${colors.red}- expected${colors.white}`;
+  const errorMsg = message || kReadableOperator[operator];
+  const msg = `${errorMsg}\n${colors.green}+ actual${colors.white} ${colors.red}- expected${colors.white}`;
   const skippedMsg = ` ${colors.blue}...${colors.white} Lines skipped`;
 
   let lines = actualLines;
@@ -337,7 +337,11 @@ class AssertionError extends Error {
     if (isErrorStackTraceLimitWritable()) Error.stackTraceLimit = 0;
 
     if (message != null) {
-      super(String(message));
+      if (operator === 'deepStrictEqual' || operator === 'strictEqual') {
+        super(createErrDiff(actual, expected, operator, message));
+      } else {
+        super(String(message));
+      }
     } else {
       // Reset colors on each call to make sure we handle dynamically set environment
       // variables correct.

diff --git a/test/parallel/test-assert.js b/test/parallel/test-assert.js
@@ -389,9 +389,9 @@ test('Test assertion messages', () => {
   );
 
   assert.throws(
-    () => assert.strictEqual(1, 2, 'oh no'),
+    () => assert.strictEqual(1, 2, 'Expected values to be strictly equal:\n\n1 !== 2\n'),
     {
-      message: 'oh no',
+      message: 'Expected values to be strictly equal:\n\n1 !== 2\n',
       generatedMessage: false
     }
   );
@@ -1204,7 +1204,7 @@ test('Additional assert', () => {
       ),
       {
         actual,
-        message,
+        message: "message\n+ actual - expected\n\n+ 'foobar'\n- {\n-   message: 'foobar'\n- }",
         operator: 'throws',
         generatedMessage: false
       }
@@ -1251,6 +1251,17 @@ test('Additional assert', () => {
     }
   );
 
+  assert.throws(
+    () => {
+      assert.deepStrictEqual({ a: true }, { a: false }, 'custom message');
+    },
+    {
+      code: 'ERR_ASSERTION',
+      name: 'AssertionError',
+      message: 'custom message\n+ actual - expected\n\n  {\n+   a: true\n-   a: false\n  }'
+    }
+  );
+
   {
     let threw = false;
     try {