turbo87 / chai-roughly Goto Github PK

Great plugin! It would be excellent if it also worked with regular equals assertions.

expect(3.99999).to.roughly.equal(4) --> true

When using .roughly(), when a test (legitimately) fails, the error message is misleading. Here is an example:

const chai = require('chai');

const { expect } = chai;
chai.use(require('chai-roughly'));

describe('example test set', () => {
  it('example test', () => {
    const expected = { num1: 12.39197,   num2: 5, num3: 19 };
    const actual =   { num1: 12.3919725, num2: 5, num3: 17 };
    expect(actual).to.roughly(0.001).deep.equal(expected); // fails (which is correct)
  });

});

The issue isn't that the test fails. The issue is that the failure message looks like this:

      AssertionError: expected { num1: 12.3919725, num2: 5, num3: 17 } to roughly deeply equal { num1: 12.39197, num2: 5, num3: 19 }
      + expected - actual

       {
      -  "num1": 12.3919725
      +  "num1": 12.39197
         "num2": 5
      -  "num3": 17
      +  "num3": 19
       }

This makes it look like the different values for num1 are also part of the reason why it failed, but the only reason it failed is that the num3 values are not within range. If you edit the num3 values to match, the test no longer fails.

Error raised for:

expect({ value: 0 }).to.roughly.deep.equal({ value: 1e-17 });

which is wrong since 1e-17 < 1e-6 (default tolerance)

We ran into some issues with our build today that came back chai-roughly depending on a forked version of deep-eql. Is it possible to un-fork deep-eql at this point? What was the reason for the fork?

cc @wittrock

Nice work on this! It's a feature I've always thought was missing from Chai.

In case there are other TypeScript users out there, you can get this to type-check in TS by putting this in a chai-roughly.d.ts file somewhere:

declare module '~chai/lib/Assertion' {
  export interface Assertion {
    roughly: RoughAssertion;
  }

  interface RoughAssertion extends Assertion {
    (tolerance: number): Assertion;
  }
}

I need the same functionality but i need to use it with .include"operator". Can you provide some guidance on how to do it ? thank you.