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Allowing messages

Test doubles are "strict" by default -- messages that have not been specifically allowed or expected will trigger an error. Use allow(...).to receive(...) to configure which messages the double is allowed to receive. You can also use allow(...).to receive_messages(...) to configure allowed messages (and return values) in bulk.

Allowed messages return nil by default​

Given a file named "allow_message_spec.rb" with:

RSpec.describe "allow" do
  it "returns nil from allowed messages" do
    dbl = double("Some Collaborator")
    allow(dbl).to receive(:foo)
    expect(dbl.foo).to be_nil
  end
end

When I run rspec allow_message_spec.rb

Then the examples should all pass.

Messages can be allowed in bulk using receive_messages​

Given a file named "receive_messages_spec.rb" with:

RSpec.describe "receive_messages" do
  it "configures return values for the provided messages" do
    dbl = double("Some Collaborator")
    allow(dbl).to receive_messages(:foo => 2, :bar => 3)
    expect(dbl.foo).to eq(2)
    expect(dbl.bar).to eq(3)
  end
end

When I run rspec receive_messages_spec.rb

Then the examples should all pass.