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More about adding a collaborator`any_instance`
any_instance
is the old way to stub or mock any instance of a class but carries the baggage of a global monkey patch on all classes.
Note that we generally recommend against using this feature.
- Background
-
- Given
-
a file named "spec/spec_helper.rb" with:
RSpec.configure do |config| config.mock_with :rspec do |mocks| mocks.syntax = :should end end
- And
-
a file named ".rspec" with:
--require spec_helper
- Scenarios
-
- Stub a method on any instance of a class
- Stub multiple methods on any instance of a class
- Stubbing any instance of a class with specific arguments
- Block implementation is passed the receiver as first arg
- Expect a message on any instance of a class
- Stub a method on any instance of a class
-
- Given
-
a file named "spec/example_spec.rb" with:
RSpec.describe "Stubbing a method with any_instance" do it "returns the specified value on any instance of the class" do Object.any_instance.stub(:foo).and_return(:return_value) o = Object.new expect(o.foo).to eq(:return_value) end end
- When
-
I run
rspec spec/example_spec.rb
- Then
- the examples should all pass
- Stub multiple methods on any instance of a class
-
- Given
-
a file named "spec/example_spec.rb" with:
RSpec.describe "Stubbing multiple methods with any_instance" do it "returns the specified values for the givne messages" do Object.any_instance.stub(:foo => 'foo', :bar => 'bar') o = Object.new expect(o.foo).to eq('foo') expect(o.bar).to eq('bar') end end
- When
-
I run
rspec spec/example_spec.rb
- Then
- the examples should all pass
- Stubbing any instance of a class with specific arguments
-
- Given
-
a file named "spec/example_spec.rb" with:
RSpec.describe "Stubbing any instance with arguments" do it "returns the stubbed value when arguments match" do Object.any_instance.stub(:foo).with(:param_one, :param_two).and_return(:result_one) Object.any_instance.stub(:foo).with(:param_three, :param_four).and_return(:result_two) o = Object.new expect(o.foo(:param_one, :param_two)).to eq(:result_one) expect(o.foo(:param_three, :param_four)).to eq(:result_two) end end
- When
-
I run
rspec spec/example_spec.rb
- Then
- the examples should all pass
- Block implementation is passed the receiver as first arg
-
- Given
-
a file named "spec/example_spec.rb" with:
RSpec.describe "Stubbing any instance of a class" do it 'yields the receiver to the block implementation' do String.any_instance.stub(:slice) do |value, start, length| value[start, length] end expect('string'.slice(2, 3)).to eq('rin') end end
- When
-
I run
rspec spec/example_spec.rb
- Then
- the examples should all pass
- Expect a message on any instance of a class
-
- Given
-
a file named "spec/example_spec.rb" with:
RSpec.describe "Expecting a message on any instance of a class" do before do Object.any_instance.should_receive(:foo) end it "passes when an instance receives the message" do Object.new.foo end it "fails when no instance receives the message" do Object.new.to_s end end
- When
-
I run
rspec spec/example_spec.rb
- Then
-
it should fail with the following output:
2 examples, 1 failure Exactly one instance should have received the following message(s) but didn't: foo
Last published over 7 years ago by myronmarston.