Chai期望有更多的人将不与Chai-Immutable合作

Question

AssertionError: expected 'List [ List [ 0, "a", 0, 0 ], List [ 0, 0, 0, 0 ], List [ 0, 0, 0, 0 ], List [ 0, 0, 0, 0 ] ]' to include 'a'

I use Chai and chai-immutable .

I am calling:

expect(nextState).to.deep.include("a");

Why doesn't this work?

Answer 1

Note that even though .include() is overridden by chai-immutable , it behaves just like Chai does on native arrays:

Consider:

expect([
  [0, "a", 0, 0],
  [0, 0, 0, 0],
  [0, 0, 0, 0],
  [0, 0, 0, 0],
]).to.deep.include("a");

This fails with:

 AssertionError: expected [ Array(4) ] to include 'a'

To solve this, I see at least 2 ways to do so (as far as I know) using Chai alone. There might also be Chai plugins to help you with this.

Using .flatten

Immutable.js List s come with .flatten() which would flatten your matrix of List s into a single List :

expect(new List([
  new List([0, "a", 0, 0]),
  new List([0, 0, 0, 0]),
  new List([0, 0, 0, 0]),
  new List([0, 0, 0, 0]),
]).flatten()).to.deep.include("a");

A failure would output like this:

AssertionError: expected 'List [ 0, "a", 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 ]' to include 'z'

Using .satisfy

Chai has a .satisfy() assertion that allows for more manual control:

expect(new List([
  new List([0, "a", 0, 0]),
  new List([0, 0, 0, 0]),
  new List([0, 0, 0, 0]),
  new List([0, 0, 0, 0]),
])).to.satisfy(matrix => matrix.some(row => row.includes("a")));

This avoids flattening the value being tested against, but because chai-immutable does not override .satisfy() , the output in case of failure is not too pretty:

AssertionError: expected { Object (size, _origin, ...) } to satisfy [Function]