expect matchers

expect.rb

Object identity
expect(actual).to be(expected) # passes if actual.equal?(expected)

Object equivalence
expect(actual).to eq(expected) # passes if actual == expected

Comparisons
expect(actual).to be >  expected
expect(actual).to be >= expected


Types/classes/response
expect(actual).to be_instance_of(expected)
expect(actual).to be_kind_of(expected)
expect(actual).to respond_to(expected)

Truthiness and existentialism
expect(actual).to be_truthy    # passes if actual is truthy (not nil or false)
expect(actual).to be true      # passes if actual == true
expect(actual).to be_nil       # passes if actual is nil
expect(actual).to exist        # passes if actual.exist? and/or actual.exists? 

Collection membership #like yesterday's quiz (include?)
expect(actual).to include(expected)
expect(array).to match_array(expected_array)# ...which is the same as:

Change observation
expect { object.action }.to change(object, :value).from(old).to(new)
expect { object.action }.to change(object, :value).by(delta)