Jest's expect toBeInstanceOf fails in rules_nodejs

[aherrmann]

🐞 bug report

Affected Rule

The issue is caused by the rule: jest_test from @npm//jest-cli:index.bzl

Is this a regression?

Not that I'm aware of.

Description

A jest test making use of expect(...).toBeInstanceOf(...) fails when it should succeed, the same test succeeds when run using yarn test.

🔬 Minimal Reproduction

• Checkout https://github.com/aherrmann/mock_class_mismatch (master fec40bbe7159854dbcb6c6f9ab81e28aa624e5d8 at the time of writing).
• Execute

  $ bazel test //:repro --test_output=streamed
  

• Observe the following test failure:

    ...
    expect(received).toBeInstanceOf(expected)
  
    Expected constructor: Server
    Received constructor: Server
  
      10 |   console.log(ws.server.constructor);  // [Function: Server] { of: [Function: of] }
      11 |   console.log(Server);  // [Function: Server] { of: [Function: of] }
    > 12 |   expect(ws.server).toBeInstanceOf(Server);  // FAILS
         |                     ^
      13 | });
      14 |
    ...
  

• For comparison, run the test with yarn and see it succeed:

  $ yarn test
  

🔥 Exception or Error

  ...
  expect(received).toBeInstanceOf(expected)

  Expected constructor: Server
  Received constructor: Server

    10 |   console.log(ws.server.constructor);  // [Function: Server] { of: [Function: of] }
    11 |   console.log(Server);  // [Function: Server] { of: [Function: of] }
  > 12 |   expect(ws.server).toBeInstanceOf(Server);  // FAILS
       |                     ^
    13 | });
    14 |
  ...

🌍 Your Environment

Operating System:

  
Ubuntu 19.10
  

Output of bazel version:

  
2.0.0
  

Rules_nodejs version:

(Please check that you have matching versions between WORKSPACE file and @bazel/* npm packages.)

  
1.1.0
  

Anything else relevant?

• yarn version 1.21.11

• node version 13.7.0 under yarn, tried both 12.13.0 and 13.7.0 under bazel, issue observed in both cases.

• node_modules contains multiple versions (.cjs.js, .es.js, ...) for the packages jest-websocket-mock and mock-socket.

  $ ls node_modules/jest-websocket-mock/lib/
  index.d.ts                  jest-websocket-mock.es.js  queue.d.ts
  jest-websocket-mock.cjs.js  matchers.d.ts              websocket.d.ts
  $ ls node_modules/mock-socket/dist/
  mock-socket.amd.js  mock-socket.es.js   mock-socket.js
  mock-socket.cjs.js  mock-socket.es.mjs
  

  It may be that the class Server is loaded from different versions between jest-websocket-mock and mock-socket and that this causes the discrepancy.

  Using --node-options=--trace-event-categories=node I've tried tracing which formats are loaded. Indeed, under yarn I see that both modules are loaded from .cjs.js files, while under Bazel jest-websocket-mock is loaded from .cjs.js but mock-socket from plain .js.

  However, I tried patching both packages to drop all but .cjs.js files and the issue persists. I've verified with --trace-event-categories that in this case only .cjs.js versions are loaded and the node_modules folder in the sandbox only contains .cjs.js files.

• There are cases under which isinstanceof is problematic in jest (Jest globals differ from Node globals jestjs/jest#2549), however, to my understanding we shouldn't be affected by this issue in this case. If, we should be hitting it in yarn as well, and I've tried the suggested SingleContextNodeEnvironment workaround without success.

• I tried using Babel as described in the jest example in the rules_nodejs repository but also without success.

• Test with Jest and Enzyme Internal Error #1651 could be a related issue.

• Further context in Jest vs Bazel: Something is broken digital-asset/daml#5367

[gregmagolan]

Thanks for the repo! I was just about to work on a repro for this issue I'm fixing the underlying cause so this is very helpful.

It is fixed in different ways by both #1800 and #1805. #1800 has landed and #1805 is going to land today so the issue should be resolved on the next release which should come later today or tomorrow.

Marking as fixed since #1800 was merged yesterday.

[gregmagolan]

Added your repo to rules_nodejs for coverage. #1814. Should be green since #1800 has already landed.

[aherrmann]

@gregmagolan Thanks a lot, that's great news. I can confirm that the issue is resolved with rules_nodejs 1.6.0.

[whilp]

I see that the jest-serializer pin is still present in package.json as of 1.6.0:

https://github.com/bazelbuild/rules_nodejs/blob/bd83907954d1b3cd53dff01c37e3c4964890ef5c/package.json#L93-L96

Is there another bug that needs to be resolved before that pin can be removed?

[whilp]

Hi! the jest-serializer pin is still present:

https://github.com/bazelbuild/rules_nodejs/blob/58fe08b6e4944be5b32261915b91c57bc9a89426/package.json#L100-L103

Is it still needed?