How do you mock a push into a class array variable using Rspec? Here is an over-simplified example:
class Foo
attr_accessor :bar
def initialize
@bar = []
end
end
def some_method(foo)
foo.bar << "a"
end
Say I want to write a spec for some_method that "it should push a new value to bar". How do I do that?
foo = Foo.new
foo.should_receive(WHAT GOES HERE???).with("a")
some_method(foo)
Why mock anything? You only need to mock something when it is a dependency that you are trying to isolate from what you are actually trying to test. In your case, you seem to be trying to verify that calling some_method results in adding an item to a property of an object you passed in. You can simply test it directly:
foo = Foo.new
some_method(foo)
foo.bar.should == ["a"]
foo2 = Foo.new
foo2.bar = ["z", "q"]
some_method(foo2)
foo2.bar.should == ["z", "q", "a"]
# TODO: Cover situation when foo.bar is nil since it is available as attr_accessor
# and can be set from outside of the instance
* EDITED After Comments Below **
foo = Foo.new
bar = mock
foo.should_receive(:bar).and_return bar
bar.should_receive(:<<).with("a")
some_method(foo)
has_and_belongs_to_many (HABTM) association. Thank you :)Example from docs: http://rubydoc.info/gems/rspec-mocks/frames
double.should_receive(:<<).with("illegal value").once.and_raise(ArgumentError)
foo.should_receive(:<<).with("a")