Connor Peet a0b548807a eng: add assertHeap method for memory assertions (#198334) ...

This adds an `assertHeap` function that can be used in tests. It
takes a heap snapshot, and asserts the state of classes in memory. This
works in Node and the Electron sandbox, but is a no-op in the browser.
Snapshots are process asynchronously and will report failures at the end
of the suite.

This method should be used sparingly (e.g. once at the end of a suite to
ensure nothing leaked before), as gathering a heap snapshot is fairly
slow, at least until V8 11.5.130 (https://v8.dev/blog/speeding-up-v8-heap-snapshots).

When used, the function will ensure the test has a minimum timeout
duration of 20s to avoid immediate failures.

It takes options containing a mapping of class names, and assertion functions
to run on the number of retained instances of that class. For example:

```ts
assertSnapshot({
	classes: {
		ShouldNeverLeak: count => assert.strictEqual(count, 0),
		SomeSingleton: count => assert(count <= 1),
	}
});
```

Closes https://github.com/microsoft/vscode/issues/191920

2023-11-15 10:41:22 -08:00

2.4 KiB

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