I have a method which returns an array. I need to test it using rspec. Is there any method with which we can test like:
def get_ids
####returns array of ids
end
subject.get_ids.should be_array
or
result = subject.get_ids
result.should be an_instance_of(Array)
Well, depends on what exactly you're looking for.
To check if the returned value is an array (be_an_instance_of):
expect(subject.get_ids).to be_an_instance_of(Array)
or to check if the returned value matches the content of expected array (match_array):
expect(subject.get_ids).to match_array(expected_array)
Update:
As mentioned in Patrick's comment, to check equivalence match of array use eq:
expect(subject.get_ids).to eq(expected_array)
For identity match of array use equal:
expect(subject.get_ids).to equal(expected_array)
eq will also work if you know the contents of the array. I think in this case it is best to do an exact match.
eq will do an exact match while match_array will check if contents of the source array matches exactly with the target array, i.e., expect([1, 2, 3]).to match_array([3, 2, 1]) will work while expect([1, 2, 3]).to eq([3, 2, 1]) won't. Or I misunderstood your point? Here, you may not know the order of ids you get from the method, so you might not want to do an exact array match, instead better to do an exact content match.eq and only when I notice that I don't care about order, I switch to match_array. It is easy to form a habit using match_array and then miss cases where the order is important. Same principle applies to other kinds of assertions, for example I prefer eq('Hello, Zaphod!') above match(/Zaphod/). It's easier to understand and at the same time more specific. Of course there are exceptions to this, above all when you don't want your tests to break when other units change.match_array if you're testing a sorting/filtering functionality.each due to duck typing.
result.class.should eq Array