fix: support errors with circular dependencies in object values with --parallel

lib/nodejs/serializer.js

@@ -262,9 +262,15 @@ class SerializableEvent {
     breakCircularDeps(result.error);
 
     const pairs = Object.keys(result).map(key => [result, key]);
-
+    const seenPairs = new Set();
     let pair;
+
     while ((pair = pairs.shift())) {
+      if (seenPairs.has(pair[1])) {
+        continue;
+      }
+
+      seenPairs.add(pair[1]);
       SerializableEvent._serialize(pairs, ...pair);
     }
 

lib/utils.js

@@ -675,7 +675,9 @@ exports.breakCircularDeps = inputObj => {
 
     seen.add(obj);
     for (const k in obj) {
-      if (Object.prototype.hasOwnProperty.call(obj, k)) {
+      const descriptor = Object.getOwnPropertyDescriptor(obj, k);
+
+      if (descriptor && descriptor.writable) {
         obj[k] = _breakCircularDeps(obj[k], k);
       }
     }

test/integration/fixtures/parallel/circular-error-object.mjs

@@ -0,0 +1,15 @@
+import {describe,it} from "../../../../index.js";
+
+describe('test1', () => {
+  it('test', () => {
+    const errorA = {};
+    const objectB = {toA: errorA};
+    errorA.toB = objectB;
+
+    const error = new Error("Oh no!");
+    error.error = errorA;
+    error.values = [errorA];
+
+    throw error;
+  });
+});

test/integration/fixtures/parallel/getter-error-object.mjs

@@ -0,0 +1,15 @@
+import {describe, it} from '../../../../index.js';
+
+describe('test1', () => {
+  it('test', async () => {
+    const error = new Error('Oh no!');
+
+    error.nested = {
+      get inner() {
+        return 'abc';
+      }
+    };
+
+    throw error;
+  });
+});

test/integration/parallel.spec.js

@@ -31,8 +31,8 @@ describe('parallel run', () => {
     assert.strictEqual(result.stats.passes, 3);
   });
 
-  it('should correctly handle circular references in an exception', async () => {
-    const result = await runMochaJSONAsync('parallel/circular-error.mjs', [
+  it('should correctly handle circular array references in an exception', async () => {
+    const result = await runMochaJSONAsync('parallel/circular-error-array.mjs', [
       '--parallel',
       '--jobs',
       '2',
@@ -45,7 +45,7 @@ describe('parallel run', () => {
   });
 
   it('should correctly handle an exception with retries', async () => {
-    const result = await runMochaJSONAsync('parallel/circular-error.mjs', [
+    const result = await runMochaJSONAsync('parallel/circular-error-array.mjs', [
       '--parallel',
       '--jobs',
       '2',
@@ -58,4 +58,29 @@ describe('parallel run', () => {
     assert.strictEqual(result.failures[0].err.message, 'Foo');
     assert.strictEqual(result.failures[0].err.foo.props[0], '[Circular]');
   });
+
+  it('should correctly handle circular object references in an exception', async () => {
+    const result = await runMochaJSONAsync('parallel/circular-error-object.mjs', [
+      '--parallel',
+      '--jobs',
+      '2',
+      require.resolve('./fixtures/parallel/testworkerid1.mjs')
+    ]);
+    assert.strictEqual(result.stats.failures, 1);
+    assert.strictEqual(result.stats.passes, 1);
+    assert.strictEqual(result.failures[0].err.message, 'Oh no!');
+    assert.deepStrictEqual(result.failures[0].err.values, [ { toB: { toA: '[Circular]' } } ]);
+  });
+
+  it('should correctly handle a non-writable getter reference in an exception', async () => {
+    const result = await runMochaJSONAsync('parallel/getter-error-object.mjs', [
+      '--parallel',
+      '--jobs',
+      '2',
+      require.resolve('./fixtures/parallel/testworkerid1.mjs')
+    ]);
+    assert.strictEqual(result.stats.failures, 1);
+    assert.strictEqual(result.stats.passes, 1);
+    assert.strictEqual(result.failures[0].err.message, 'Oh no!');
+  });
 });