assert-match

assert-match is a set of additional assertions focused on matching. Unlike standard deep equality comparision assertions, which requires two arguments to have exactly the same sets of properties, assert-match' assertions requires one's arg properties to be superset of another arg properties.

Rationale

There are times when I need to check only subset of an object porperties to have specific values. Hence this module. An alternative approach would be to use a combination of standard assert and some utility library providing matching capability, for example _.isMatch. assert-match has the following advantages:

• it provides your test runner with the hints on actual and expected outcomes of the test
• gives your more consistent results with family of standard deep-assertions

Installation

    npm install assert-match

Usage

assert (obj)

The function returned by the module. Can be used to extend any passed obj object in it, for example, standard assert module:

const assert = require('assert')
require('assert-match')(assert)

// ...

assert.match(actual, expected)

assert-match can also be used standalone:

const assert = require('assert-match')

// ...

assert.match(actual, expected)

Assertions

assert.match (actual, expected, message)

Tests whether the set of properties of the actual arg is superset of expected arg properties. Optional custom message is set on error when the assertion fails. Primitive values are compared with ==. Comparable to standard assert's deepEqual assertion but with another requirement on properties sets comparison.

assert.strictMatch (actual, expected, message)

Same as match, but primitives are compared with ===. Comparable to assert's deepStrictEqual.

assert.notMatch (actual, expected, message)

Same as match, but primitives are compared with !=. Comparable to assert's notDeepEqual.

assert.notStrictMatch (actual, expected, message)

Same as match, but primitives are compared with !==. Comparable to assert's notDeepStrictEqual.

Examples

import assert from 'assert-match'

describe('examples', function () {

    it('matches primitives', function () {
        assert.match(5, '5')
    })

    it('matches primitives strictly', function () {
        assert.strictMatch(5, 5)
    })

    it('matches objects', function () {
        assert.match({a: 1, b: 2, c: 3}, {a: 1})
    })

    it('throws when objects do not match', function () {
        assert.match({a: 1, b: 2, c: 3}, {a: 10})
    })

})

// RESULT

//   examples
//     ✓ matches primitives
//     ✓ matches primitives strictly
//     ✓ matches objects
//     1) throws when objects do not match


//   3 passing (82ms)
//   1 failing

//   1) examples throws when objects do not match:

//       AssertionError: { a: 1 } match { a: 10 }
//       + expected - actual

//        {
//       -  "a": 1
//       +  "a": 10
//        }