Description
Do you want to request a feature or report a bug?
bug
What is the current behavior?
Jest --detectLeaks is reporting leaks even on very minimal test suites.
I've set up an example repo here: https://github.com/kand/jest-22-mem-leak
There are two test files:
describe('memory leak suite 1', () => {
it('happens', () => {
console.log('suite 1 > test 1 > ran test');
});
});
describe('memory leak suite 2', () => {
it('happens', () => {
console.log('suite 2 > test 1 > ran test');
});
});
As well as some added console.log statements in node_modules/jest-leak-detector/build/index.js:
// line 51
console.log('[IN JEST (line 52)] attaching GC listener to', value.constructor.name);
weak(value, () => {
console.log('[IN JEST (line 54)] garbage collected value');
this._isReferenceBeingHeld = false
});
this._isReferenceBeingHeld = true;
// Ensure value is not leaked by the closure created by the "weak" callback.
value = null;
}
isLeaking() {
this._runGarbageCollector();
console.log('[IN JEST (line 66)] checking leak');
return this._isReferenceBeingHeld;
}
// line 69
Which produces the following output when tests are run:
yarn test v1.0.2
$ jest --detectLeaks --runInBand
FAIL ./file-1.test.js
● Test suite failed to run
EXPERIMENTAL FEATURE!
Your test suite is leaking memory. Please ensure all references are cleaned.
There is a number of things that can leak memory:
- Async operations that have not finished (e.g. fs.readFile).
- Timers not properly mocked (e.g. setInterval, setTimeout).
- Keeping references to the global scope.
at node_modules/jest-cli/build/test_scheduler.js:115:22
[IN JEST (line 52)] attaching GC listener to JSDOMEnvironment
[IN JEST (line 66)] checking leak
[IN JEST (line 52)] attaching GC listener to JSDOMEnvironment
FAIL ./file-2.test.js
● Test suite failed to run
EXPERIMENTAL FEATURE!
Your test suite is leaking memory. Please ensure all references are cleaned.
There is a number of things that can leak memory:
- Async operations that have not finished (e.g. fs.readFile).
- Timers not properly mocked (e.g. setInterval, setTimeout).
- Keeping references to the global scope.
at node_modules/jest-cli/build/test_scheduler.js:115:22
Test Suites: 2 failed, 2 total
Tests: 0 total
Snapshots: 0 total
Time: 0.734s
Ran all test suites.
[IN JEST (line 54)] garbage collected value
[IN JEST (line 66)] checking leak
error Command failed with exit code 1.
info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.
It doesn't appear that either of these tests should be producing a memory leak. Memory leaks are also reported when --runInBand is not used. It looks like the leak detector is checking for memory leaks before the JSDOMEnvironment object is cleaned up, which causes jest to report a memory leak, though I'm sure this is not the root cause.
I believe these issues are related:
#1893
jsdom/jsdom#1682
jsdom/jsdom#1682
But 2 are closed and the open one hasn't had activity in a while.
What is the expected behavior?
No memory leaks are reported.
Please provide your exact Jest configuration and mention your Jest, node,
yarn/npm version and operating system.
[email protected]
[email protected]
[email protected]
[email protected]
macOS Sierra (version 10.12.6)