how to unmock a single instance method with jest
Solution 1
mockFn.mockRestore()
worked for me with [email protected]
:
// Create a spy with a mock
const consoleInfoSpy = jest.spyOn(console, 'info').mockImplementation(() => {})
// Run test or whatever code which uses console.info
console.info('This bypasses the real console.info')
// Restore original console.info
consoleInfoSpy.mockRestore()
Solution 2
This does not strictly apply to the OP, but answer-seekers may end up here. You can mock a module except certain parts for all tests like so.
mocks/saladMaker.js
// Let Jest create the mock.
const saladMaker = jest.genMockFromModule('../saladMaker');
// Get the unmocked chop method.
const {chop} = require.requireActual('../saladMaker');
// Patch it in.
saladMaker.chop = chop;
module.exports = saladMaker;
The key part is to use requireActual
to get at the unmocked module.
Update
require.requireActual
has been replaced with jest.requireActual
.
Solution 3
It is not possible to get the original module after mocking it in Jest. What jest.mock
does is to replace the module with your mock.
So even you write:
Foo = require('foo')
jest.mock('foo')
Jest will hoist the jest.mock('foo')
call on top of the call stack, so it's the first thing that happens when the test starts. This will also affect all other modules you import and that import foo.js
.
You could try to use spyOn
to spy on functions of an object, should work with classes as well, but I'm not quite sure.
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brewster
Updated on February 05, 2022Comments
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brewster about 2 years
coming from rspec, i am having trouble understanding mocking with jest. the approach i am trying for, is to automock a class's constructor and all of it's functions, and then unmock them one by one to test only that one function. the only documentation i can find on it, is with using 2 classes, mocking 1 class, and then testing that those functions are called from the other unmocked class.
below is a basic, contrived idea of what i am trying to do. can someone direct me to the jest-way of doing this?
foo.js
class Foo constructor: -> this.bar() this.baz() bar: -> return 'bar' baz: -> return 'baz'
foo_test.js
// require the class Foo = require('foo') // mock entire Foo class methods jest.mock('foo') // unmock just the bar method jest.unmock(Foo::bar) // or by Foo::bar.mockRestore() // and should now be able to call foo = new Foo foo.bar() // 'bar' foo.baz() // undefined (still mocked) // i even tried unmocking the instance foo = new Foo jest.unmock(foo.bar) foo.bar.mockRestore()
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brewster over 5 yearsyea i have been playing with that too, but having the same issue. i was also looking at try to just mock the constructor, but can't seem to figure that out either. somehow jest is doing it, but looking through their source code may take longer than just figuring it out myself
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sankalp almost 3 yearsjest.genMockFromModule() is deprecated so we can use jest.createMockFromModule()