How can I run a snapshot test which contains a call to a static method?

Question

In my react/jest unit test I am trying to call a static method called getSortedAppColumns(), this is part of the component:

static getSortedAppColumns = (appColumns, sortBy, criticalFirst) => {
...
return { id, applications: applicationsSorted, ...rest };
});
};

When I run this test:

it('should sort', () => {
    const presets = { presets: { sortCriteria: 'name' } };
    const component = (
      <AppTrackerContainer applicationStages={applicationStages} {...presets} />
    );
    const wrapper = shallow(component);
    const instance = wrapper.instance();
    const appList = applicationStages[0].applications;
    expect(instance.getSortedAppColumns(appList)).toMatchSnapshot();
});

Of course I have this error:

TypeError: instance.getSortedAppColumns is not a function

  45 |     const instance = wrapper.instance();
  46 |     const appList = applicationStages[0].applications;
> 47 |     expect(instance.getSortedAppColumns(appList)).toMatchSnapshot();

Obviously a static method is not an instance but how can I utilise this static call in my jest snapshottest? Need to have a snapshot test that is the bottom line.

You can't access static members directly on the instance *in general*, this isn't anything to do with Jest (they're on the prototype). But if the static method is just a helper for the rest of what the component is doing, I wouldn't test it directly anyway; test the overall *behaviour* not your current implementation. — jonrsharpe, Feb 11 '19 at 08:34

score 2 · Accepted Answer · answered Feb 11 '19 at 08:43

2

AppTrackerContainer.getSortedAppColumns(appList)

js call static method from class

answered Feb 11 '19 at 08:43

nubinub

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I agree you can call the static method like this but what about all the props you are passing in then? – bier hier Feb 11 '19 at 09:24
Which props are you referring to ? – nubinub Feb 11 '19 at 09:25
wrapper etc. see above – bier hier Feb 11 '19 at 09:32
I don't understand. Wrapper is not a prop, it is a [ShallowWrapper](https://airbnb.io/enzyme/docs/api/shallow.html) created by enzyme which wraps your AppTrackerContainer component. – nubinub Feb 11 '19 at 09:34
By the way if your main goal is just to test that static method, you truly don't need a wrapper and everything else. – nubinub Feb 11 '19 at 09:41

How can I run a snapshot test which contains a call to a static method?

1 Answers1