assert.propContains()

Categories: Assertions.

version added: 2.18.0.

Description

propContains( actual, expected, message = "" )

Check that an object contains certain properties.

name description
actual Expression being tested
expected Known comparison value
message (string) Short description of the actual expression

The propContains assertion compares only the subset of properties in the expected object, and tests that these keys exist as own properties with strictly equal values.

This method is recursive and allows partial comparison of nested objects as well.

See also

Examples

Example: Usage

QUnit.test('example', function (assert) {
  const result = {
    foo: 0,
    vehicle: {
      timeCircuits: 'on',
      fluxCapacitor: 'fluxing',
      engine: 'running'
    },
    quux: 1
  };

  assert.propContains(result, {
    foo: 0,
    vehicle: { fluxCapacitor: 'fluxing' }
  });

  function Point (x, y, z = 0) {
    this.x = x;
    this.y = y;
    this.z = z;
  }

  assert.propContains(
    new Point(10, 20),
    { y: 20 }
  );

  assert.propContains(
    [ 'a', 'b' ],
    { 1: 'b' }
  );

  const nested = {
    north: [ /* ... */ ],
    east: new Point(10, 20),
    south: [ /* ... */ ],
    west: [ /* ... */ ]
  };

  assert.propContains(nested, { east: new Point(10, 20) });
  assert.propContains(nested, { east: { x: 10, y: 20 } });
  assert.propContains(nested, { east: { x: 10 } });
});

Example: Alternative

assert.propContains(
  new Point(10, 20, 30),
  { x: 10, z: 30 }
);

This is like the following, but without needing to describe each assertion, and without temporary variable.

const myPlace = new Point(10, 20, 30);
assert.strictEqual(myPlace.x, 10, 'x property');
assert.strictEqual(myPlace.z, 30, 'z property');