🐛 Bug: Watch + mochaHooks inconsistent state on re-runs #5149
Description
Bug Report Checklist
- I have read and agree to Mocha's Code of Conduct and Contributing Guidelines
- I have searched for related issues and issues with the
faq
label, but none matched my issue. - I have 'smoke tested' the code to be tested by running it outside the real test suite to get a better sense of whether the problem is in the code under test, my usage of Mocha, or Mocha itself.
- I want to provide a PR to resolve this
Expected
Mocha's watch mode should produce the same results on all runs, if the code does not change significantly (e.g. triggered by adding a new line.). Using mochaHooks
that mutate globals and modules/requires should be consistent in all runs.
Failing on watch reload
mochaHooks beforeEach(): [ 'testItem1', 'testItem2' ]
✔ should return two items
Always working
mochaHooks beforeEach(): [ 'testItem1', 'testItem2' ]
✔ should return two items
2 passing (2ms)
Actual
Mocha's watch mode seems to not work the same on reloads regarding mochaHooks
as in the 1st run.
Having a beforeEach()
that require
s a fil, and which we mutate state of in that hook, when a test that relies on that mutated state runs, first time is ok, but subsequent "watch runs" fail.
First run is ok, but then any irrelevant change on a watched file:
Failing on watch reload
mochaHooks beforeEach(): [ 'testItem1', 'testItem2' ]
1) should return two items
Always working
mochaHooks beforeEach(): [ 'testItem1', 'testItem2' ]
✔ should return two items
1 passing (13ms)
1 failing
1) Failing on watch reload
should return two items:
AssertionError [ERR_ASSERTION]: Expected values to be loosely deep-equal:
[]
should loosely deep-equal
[
'testItem1',
'testItem2'
]
+ expected - actual
-[]
+[
+ "testItem1"
+ "testItem2"
+]
at Context.<anonymous> (test/failing.test.js:8:12)
at process.processImmediate (node:internal/timers:478:21)
ℹ [mocha] waiting for changes...
Minimal, Reproducible Example
I created a small repro repo, keeping it similar to my source: https://github.com/Kartones/mocha-hooks-watcher-bug
Includes a README with steps to reproduce, but adding here a minimal TL;DR:
given:
class A {
_items = [];
initialize(items) {
this._items = items;
}
getItems() {
return this._items;
}
}
exports.A = A;
exports.a = new A();
And a hook that mutates it:
const { a } = require("../lib/a.js");
exports.mochaHooks = {
beforeEach() {
a.initialize(["testItem1", "testItem2"]);
},
};
The hook is correctly executed before each test, but a
seems to be kept at the initial state (with _items=[]
, instead of _items=["testItem1", "testItem2"]
)
Versions
Mocha: 10.4.0
NodeJS: v20.11.1
pnpm (not strictly relevant): pnpm@8.15.3
Additional Info
UPDATED: Taking a look, will provide a PR with one solution.
Activity