CODEWITHSUNDEEP
reactjsunit-testingjestjsenzyme
one-hand-octopus
one-hand-octopus

Reputation: 2743

Jest how to loop through similar test functions

I know that with Jest Globals, if you have same function to be tested with different test parameters, instead of repeating this:

describe('test year functions', () => {
    it('should return correct year', () => {
        expect(getYear(testYear)).toBe(1990);
    });
    it('should return correct year + 1', () => {
        expect(getYear(testYear + 1)).toBe(1991);
    });
});

We can do this to avoid repeating it, which is great:

describe('test year functions', () => {
    test.each`
        year         | addYear  | expected
        ${testYear}  | ${0}     | ${1990}
        ${testYear}  | ${1}     | ${1991}
    `('returns correct years', ({ year, addYear, expected }) => {
        expect(getYear(testYear + addYear)).toBe(expected);
    });
});

Now I have different functions to be tested, but the tests are quite similar:

describe('test date functions', () => {
    it('getYear(date) should return correct year', () => {
        expect(getYear(1990)).toBe(1990);
    });
    it('getMonth(date) should return correct month', () => {
        expect(getMonth(testMonth + 1)).toBe(10);
    });
});

Can I avoid the repeat of it and do something like this?

describe('test date functions', () => {
    test.each`
        function    | parameter         | expected
        ${getYear}  | ${1990}           | ${1990}
        ${getMonth} | ${testMonth + 1}  | ${10}
    `('returns correct dates', ({ function, parameter, expected }) => {
        expect(function(parameter)).toBe(expected);
    });
});

Upvotes: 2

Views: 235

Answers (1)

lissettdm
lissettdm

Reputation: 13078

Yes it is possible. You just need to change one thing:

  1. Replace function for other word because it is a reserved word:

 describe('test date functions', () => {
      test.each`
              func    | parameter         | expected
          ${getYear}  | ${1990}           | ${1990}
          ${getMonth} | ${testMonth + 1}  | ${10}
      `('returns correct dates', ({ func, parameter, expected }) => {
          expect(func(parameter)).toBe(expected);
      });
 });

I tried it and it worked.

Upvotes: 1

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