Jest: Feature Request: .toHaveProperties(arguments: string[]) matcher

[WederPachecoSilva]

What is the current behavior?
Currently Jest offers .toHaveProperty to check for a specific property inside an object
but I couldn't see an easy way of checking for multiples properties.
I am aware that Jest offers expect.extend() to make possible for us to customize a matcher,
but checking for more than one property seems quite usual to me.
Wouldn't it be interesting to have a .toHaveProperties(args) matcher that receives an array
of strings to check?

A fast and naive prototype of what I am proposing using expect.extend:
` const extend = { toHaveProperties(received, args) { const receivedProperties = Object.getOwnPropertyNames(received); const pass = !args.some(val => receivedProperties.indexOf(val) === -1); if (pass) { return { message: () => `expected ${received} not to have properties of ${args}`, pass: true, }; } else { return { message: () => `expected ${received} to have properties of ${args}`, pass: false, }; } }, }; expect.extend(extend)

[elad-yosifon]

@WederPachecoSilva seems like a pretty simple and useful feature to implement.. I’ll try to create this PR in the next couple of days..

[elad-yosifon]

@WederPachecoSilva
toHaveProperty(expectedKey, ...) enables to pass a 2nd arg expectedValue which is optional.. and passing it will assert for a matching key and value..

This behaviour complicates your original idea of passing an array of keys to expect().toHaveProperties(['key1','key2','keyN']).

I thought about passing a 2nd arg which contains matching values, passing an array of tuples or passing a literal object.
i.e.

expect().toHaveProperties(['key1','key2','keyN'],['1','2','N'])

// or...

expect().toHaveProperties([
  ['key1', '1'],
  ['key2', '2'],
  ['keyN', 'N']
])

// or...

expect().toHaveProperties({
  'key1': '1',
  'key2': '2',
  'keyN' :'N'
})

the latter opens a door to further complications.. (full matching objects vs. partial matching)

[SimenB]

If you want equality, you should use toMatchObject for partial or toEqual for full match.

[elad-yosifon]

@SimenB @WederPachecoSilva .. maybe changing the function to

expect().toHaveKeys(...keys :string[])

will be a better idea?

[SimenB]

Yeah, I think that makes more sense. I'm not sure if it's needed in Jest core, though

[mattphillips]

@elad-yosifon have you checked out jest-extended? It has support for toContainKeys which is the same API to your example toHaveKeys.

@WederPachecoSilva jest-extended also has APIs for checking entries (key/value pairs) in an object see toContainEntries

[SimenB]

I'll say that's good enough, then 🙂