CODEWITHSUNDEEP
jestjs
user128511
user128511

Reputation:

How do I get jest to ignore the fairly common `debug` node package?

I've got a node js module that looks like this

"use strict";

var debug = require('debug')('foo');

var Foo = function() {
  this.x = 123;
  debug("init");
};

module.exports = Foo;

And my test looks like this

jest.dontMock('../lib/foo');
jest.dontMock('debug');

describe('footest', function() {
 it('checks the foo', function() {
   var Foo = require('../lib/foo');
   var foo = new Foo();
   expect(foo.x).toBe(123);
 });
});

But when I run jest with 

node node_modules/jest-cli/bin/jest.js

I get

Found 1 matching tests...
 FAIL  __tests__/foo-test.js (0.02s)
? footest › it checks the foo
  - TypeError: /Users/gregg/src/jest-test/lib/foo.js: /Users/gregg/src/jest-test/node_modules/debug/node.js: Cannot read property 'buffer' of undefined
      at Socket.self [as bytesWritten] (net.js:688:8)
      at _getMetadata (/Users/gregg/src/jest-test/node_modules/jest-cli/src/lib/moduleMocker.js:279:49)
      at _getMetadata (/Users/gregg/src/jest-test/node_modules/jest-cli/src/lib/moduleMocker.js:286:23)
      at _getMetadata (/Users/gregg/src/jest-test/node_modules/jest-cli/src/lib/moduleMocker.js:279:27)
      at _getMetadata (/Users/gregg/src/jest-test/node_modules/jest-cli/src/lib/moduleMocker.js:279:27)
      at Object.module.exports.getMetadata (/Users/gregg/src/jest-test/node_modules/jest-cli/src/lib/moduleMocker.js:388:20)
      at Loader._generateMock (/Users/gregg/src/jest-test/node_modules/jest-cli/src/HasteModuleLoader/HasteModuleLoader.js:280:56)
      at Loader.requireMock (/Users/gregg/src/jest-test/node_modules/jest-cli/src/HasteModuleLoader/HasteModuleLoader.js:782:43)
      at Loader.requireModuleOrMock (/Users/gregg/src/jest-test/node_modules/jest-cli/src/HasteModuleLoader/HasteModuleLoader.js:897:17)
      at /Users/gregg/src/jest-test/node_modules/debug/node.js:6:11
      at Object.runContentWithLocalBindings (/Users/gregg/src/jest-test/node_modules/jest-cli/src/lib/utils.js:309:17)
      at Loader._execModule (/Users/gregg/src/jest-test/node_modules/jest-cli/src/HasteModuleLoader/HasteModuleLoader.js:243:9)
      at Loader.requireModule (/Users/gregg/src/jest-test/node_modules/jest-cli/src/HasteModuleLoader/HasteModuleLoader.js:879:10)
      at Loader.requireModuleOrMock (/Users/gregg/src/jest-test/node_modules/jest-cli/src/HasteModuleLoader/HasteModuleLoader.js:899:17)
      at /Users/gregg/src/jest-test/lib/foo.js:3:13
      at Object.runContentWithLocalBindings (/Users/gregg/src/jest-test/node_modules/jest-cli/src/lib/utils.js:309:17)
      at Loader._execModule (/Users/gregg/src/jest-test/node_modules/jest-cli/src/HasteModuleLoader/HasteModuleLoader.js:243:9)
      at Loader.requireModule (/Users/gregg/src/jest-test/node_modules/jest-cli/src/HasteModuleLoader/HasteModuleLoader.js:879:10)
      at Loader.requireModuleOrMock (/Users/gregg/src/jest-test/node_modules/jest-cli/src/HasteModuleLoader/HasteModuleLoader.js:899:17)
      at Spec.<anonymous> (/Users/gregg/src/jest-test/__tests__/foo-test.js:7:14)
      at Timer.listOnTimeout [as ontimeout] (timers.js:110:15)

How do I get jest to ignore the debug package and why does it appear to be making a mock when I told it not to?

Upvotes: 6

Views: 3344

Answers (3)

Gil Birman
Gil Birman

Reputation: 35900

At the top of your test file, try this:

    jest.autoMockOff();

Then manually mock files with jest.mock(..)

Update: There's a fix that doesn't require you turn off auto mocking. tldr; add debug, tty, and net to jest.unmockedModulePathPatterns in package.json

Upvotes: 0

duereg
duereg

Reputation: 146

Right now there is a bug in jest 0.1.18 (being fixed here, documented here) where core node modules cannot be ignored from being mocked.

Once the pull request is accepted by facebook, this problem should go away.

Until then, you can point your package.json to the repo of the fix: 

"jest-cli": "git://github.com/adaschevici/jest.git#cf4c6ff97d7009ff8627dd7d3a59cfeff1f3c8b8"

which should resolve that issue.

Upvotes: 3

Vova Zaycev
Vova Zaycev

Reputation: 258

The reason this happens is because jest.dontMock('debug'); will only prevent mocking the root file of the debug module, while all other internals will still be mocked.

One possible solution could be to prevent mocking debug library using unmockedModulePathPatterns configuration option:

In package.json: 
{
  "name": "...",
  "version": "0.0.0",
  ...
  "jest": {
    "unmockedModulePathPatterns": ["/node_modules/debug"]
  },
}

Upvotes: 1

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