I have two class OneClass and AnotherClass:
class OneClass
def initialize(*args)
@another_member = AnotherClass.new()
end
def my_method()
if @another_member.another_method1() then
@another_member.another_method2()
end
@another_member.another_method3()
end
end
I am getting to write unit for OneClass.
How can I mock @another_member?
With the idea of Anthony, I make it work.
describe OneClass do
before(:each) { @one_object = OneClass.new }
describe 'my_method' do
it 'should work' do
mock_member = double
allow(mock_member).to receive(:another_method1).and_return(true)
@one_object.instance_variable_set(:@another_member, mock_member)
@one_object.my_method()
expect(mock_member).to have_received(:another_method1)
end
end
end
You can't mock an instance variable. You can only mock methods. One option is to define a method inside OneClass that wraps the another_member, and mock that method.
class OneClass
def initialize(*args)
end
def my_method()
if another_member.another_method1() then
another_member.another_method2()
end
another_member.another_method3()
end
private
def another_member
@another_member ||= AnotherClass.new()
end
end
However, you don't have to, there is a better way to write and test your code. In this case a better approach to mocking is to use a pattern called Dependency Injection.
You pass your dependency to the initializer.
class OneClass
def initialize(another: AnotherClass, whatever:, somethingelse:)
@another_member = another.new()
end
def my_method()
if @another_member.another_method1() then
@another_member.another_method2()
end
@another_member.another_method3()
end
end
(Note I used keyword arguments, but you don't have to. You can also use the standard args approach).
Then, in the test suite you simply provide the test object.
let(:test_another) {
Class.new do
def another_method1
:foo
end
def another_method2
:bar
end
def another_method3
:baz
end
end
}
it "does something" do
subject = OneClass.new(another: test_another)
# ...
end
There are several advantages of this approach. In particular, you avoid using mock in the tests and you really test the object in isolation.
You can mock @another_member indirectly by stubbing AnotherClass.new:
another_member_double = double()
allow(AnotherClass).to receive(:new).and_return(another_member_double)
expect(another_member_double).to receive(:another_method1).and_return(somevalue)
