Fix a memory leak in Error objects (#6965)

CHANGELOG.md

@@ -3,6 +3,7 @@
 ### Fixes
 
 - `[jest-haste-map]` [**BREAKING**] Replaced internal data structures to improve performance ([#6960](https://github.com/facebook/jest/pull/6960))
+- `[jest-jasmine2]` Fix memory leak in Error objects hold by the framework ([#6965](https://github.com/facebook/jest/pull/6965))
 
 ### Chore & Maintenance
 

packages/jest-jasmine2/src/jasmine/Spec.js

@@ -66,6 +66,12 @@ export default function Spec(attrs: Object) {
   this.initError = new Error();
   this.initError.name = '';
 
+  // Without this line v8 stores references to all closures
+  // in the stack in the Error object. This line stringifies the stack
+  // property to allow garbage-collecting objects on the stack
+  // https://crbug.com/v8/7142
+  this.initError.stack = this.initError.stack;
+
   this.queueableFn.initError = this.initError;
 
   this.result = {

packages/jest-jasmine2/src/jasmine_async.js

@@ -37,6 +37,12 @@ function promisifyLifeCycleFunction(originalFn, env) {
 
     const extraError = new Error();
 
+    // Without this line v8 stores references to all closures
+    // in the stack in the Error object. This line stringifies the stack
+    // property to allow garbage-collecting objects on the stack
+    // https://crbug.com/v8/7142
+    extraError.stack = extraError.stack;
+
     // We make *all* functions async and run `done` right away if they
     // didn't return a promise.
     const asyncJestLifecycle = function(done) {
@@ -79,6 +85,12 @@ function promisifyIt(originalFn, env) {
 
     const extraError = new Error();
 
+    // Without this line v8 stores references to all closures
+    // in the stack in the Error object. This line stringifies the stack
+    // property to allow garbage-collecting objects on the stack
+    // https://crbug.com/v8/7142
+    extraError.stack = extraError.stack;
+
     const asyncJestTest = function(done) {
       const wrappedFn = isGeneratorFn(fn) ? co.wrap(fn) : fn;
       const returnValue = wrappedFn.call({});

packages/jest-jasmine2/src/queue_runner.js

@@ -73,6 +73,7 @@ export default function queueRunner(options: Options) {
           'Timeout - Async callback was not invoked within the ' +
           timeoutMs +
           'ms timeout specified by jest.setTimeout.';
+        initError.stack = initError.message + initError.stack;
         options.onException(initError);
       },
     );