CODEWITHSUNDEEP
vue.jsjestjs
anthonygore
anthonygore

Reputation: 4967

Jest spyOn is reporting a method was called with a different object than what it was actually called with

I'm using Jest spyOn to track a method on Vue router. The Vue method I'm testing looks like this:

myMethod() {
  this.$router.push({ name: "login" });
}

I want to ensure that $router.push was called, so in my test I have this:

const spy = jest.spyOn(wrapper.vm.$router, 'push');
expect(spy).toHaveBeenCalledWith({ name: "login" });

This test fails, though, with the error:

Expected mock function to have been called with:
        {"name": "login"}
      as argument 1, but it was called with
        {"name": "login", "params": {}, "path": "/login"}.

No problem, I can update the test to the following and it works:

expect(spy).toHaveBeenCalledWith({
  name: "login",
  params: {},
  path: "/login"
});

My question is: why does the Jest spy report that it was called with an object with three properties, but when we look at the actual method call, it only has one property?

Upvotes: 2

Views: 2769

Answers (1)

Peter Kota
Peter Kota

Reputation: 8340

vue-router add some default values to params and path properties. When you use spyOn you will detect the other parameters also which are assigned by vue-router. If you add explicit the spy to the push method then you will see only the name property.

Try this:

const spy = jest.fn();
wrapper.vm.$router.push = spy;
expect(spy).toHaveBeenCalledWith({ name: "login" });

Upvotes: 1

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