Jest expect().toEqual() not throwing error

Question

I expected the following sample test to fail if I use toEqual(), but it passes:

it('sample test to check toEqual and toBe', () => {
   const expectedAction = {test: '123', value: undefined};
   const actualAction = {test: '123'};
   expect(expectedAction).toEqual(actualAction);
})

The same test fails if I use .toBe(). However, if I fix the test case like this:

it('sample test to check toEqual and toBe', () => {
   const expectedAction = {test: '123', value: '123'};
   const actualAction = {test: '123', '123'};
   expect(expectedAction).toBe(actualAction);
});

it again fails saying that "Compared values have no visual difference".

Is the behaviour correct? How to modify my test case so that it fails correctly.

Inanda Menezes Inanda Menezes · Accepted Answer · 2017-05-04T20:58:07

If you really need it to be considered as different, one option would be to use Jest snapshot test, like:

expect(expectedAction).toMatchSnapshot();

The first time, it will create a snapshot file and print the javascript object to it, when you run the test again, it will compare it to the snapshot. Most of the times, the snapshots are used to compare the component rendered tree, but you can use it for any javascript object.

Jest expect().toEqual() not throwing error

2 Answers