TIL: How to Correctly Use a Jasmine Spy

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I often find myself stumped when trying to use spies in a JavaScript test… Until Today.

TIL: How to correctly use a Jasmine Spy:

Foo = require('foo')

  describe 'Foo'
    describe 'bar'
      it 'does a thing'
        spyOn(Foo, 'bar')
        foo = new Foo()

        expect(foo.bar).toHaveBeenCalled()

Run into no method error? Try spyOn(Foo.prototype, 'bar').

  • Jasmine is a popular JavaScript testing framework
  • Spies are a type of test double that allow you to stub functions and track the function call, and it’s arguments

For more information on Jasmine Spies, visit their documentation.

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