toBe hangs for cyclic structures

[yangshun]

Describe the bug

Not much to say here, Vitest just doesn't complete when I have a certain test case for an algo question, it hangs indefinitely.

No async operations involved.

I don't think it's a bug with my algo because I'm migrating from Jest which is able to successfully run all the test cases.

> jest "algo/graph-clone"

 PASS  algo/graph-clone/setup/src/graph-clone.test.ts

Test Suites: 2 passed, 2 total
Tests:       103 passed, 103 total
Snapshots:   0 total
Time:        1.786 s

With Vite it doesn't complete:

~/projects/vitejs-vite-jtzpyjuo 5s
❯ npm t

> [email protected] test
> vitest run


 RUN  v3.0.5 /home/projects/vitejs-vite-jtzpyjuo


 ❯ src/graph-clone.test.ts 0/8

 Test Files 0 passed (1)
      Tests 0 passed (8)
   Start at 08:44:17
   Duration 83.05s

Reproduction

https://stackblitz.com/edit/vitejs-vite-jtzpyjuo

This is a minimal repro with 8 test cases (tests.json). My original code has 100 test cases (tests.all.json).

If the last test case in tests.json is removed (L240-L384), the tests can complete.

System Info

❯ npx envinfo --system --npmPackages '{vitest*,@vitest/*,vite,@vitejs/*,playwright,webdriverio}' --binaries --browsers
Need to install the following packages:
[email protected]
Ok to proceed? (y) y

  System:
    OS: Linux 5.0 undefined
    CPU: (8) x64 Intel(R) Core(TM) i9-9880H CPU @ 2.30GHz
    Memory: 0 Bytes / 0 Bytes
    Shell: 1.0 - /bin/jsh
  Binaries:
    Node: 18.20.3 - /usr/local/bin/node
    Yarn: 1.22.19 - /usr/local/bin/yarn
    npm: 10.2.3 - /usr/local/bin/npm
    pnpm: 8.15.6 - /usr/local/bin/pnpm
  npmPackages:
    vite: ^6.0.11 => 6.0.11 
    vitest: ^3.0.5 => 3.0.5

Used Package Manager

npm

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[hi-ogawa]

Just in case, can you confirm it's not your algo getting stuck in while loop or recursion?

[hi-ogawa]

As explained in #1405, if synchronous code is taking over, then timeout doesn't kick in. You can try --disableConsoleIntercept + console.log("debug") to see if synchronous code is running in loop.

[yangshun]

Just in case, can you confirm it's not your algo getting stuck in while loop or recursion?

Yes it should not be, I am currently using Jest and it passes fine. I encountered the hanging issue while migrating to Vitest.

I did further debugging and narrowed down the issue to this line expect(clonedGraph).not.toBe(originalGraph). Commenting out this line will let the test end.

I suspect the implementation of the toBe assertion could be buggy.

[hi-ogawa]

I did further debugging and narrowed down the issue to this line expect(clonedGraph).not.toBe(originalGraph). Commenting out this line will let the test end.

I suspect the implementation of the toBe assertion could be buggy.

Okay, that's likely a bug of printing/diffing a cyclic object getting stuck in the loop.

[yangshun]

Thanks. As a workaround I've changed my code to expect(Object.is(clonedGraph, originalGraph)).toBe(false);

Updated StackBlitz repro to the minimal test case: https://stackblitz.com/edit/vitejs-vite-jtzpyjuo?file=src%2Fgraph.test.ts