Is there a jasmine matcher to compare objects on subsets of their properties

Question

I have an object that may be extended along my behavior under test, but I want to make sure that the original properties are still there.

var example = {'foo':'bar', 'bar':'baz'}

var result = extendingPipeline(example)
// {'foo':'bar', 'bar':'baz', 'extension': Function}

expect(result).toEqual(example) //fails miserably

I'd like to have a matcher that would pass in this case, along the lines of:

expect(result).toInclude(example)

I know that I can write a custom matcher, but it seems to me that this is such a common problem that a solution should be out there already. Where should I look for it?

Answer 1

Jasmine 2.0

expect(result).toEqual(jasmine.objectContaining(example))

Since this fix: https://github.com/pivotal/jasmine/commit/47884032ad255e8e15144dcd3545c3267795dee0 it even works on nested objects, you just need to wrap each object you want to match partially in jasmine.objectContaining()

Simple example:

it('can match nested partial objects', function ()
{
    var joc = jasmine.objectContaining;
    expect({ 
        a: {x: 1, y: 2}, 
        b: 'hi' 
    }).toEqual(joc({
        a: joc({ x: 1})
    }));
});