Spy pattern

spy_pattern.md

Use spy

Spies are an alternate type of test double that support this pattern by allowing you to expect that a message has been received after the fact, using have_received.

RSpec.describe "have_received" do
  it "passes when the message has been received" do
    invitation = spy('invitation')
    invitation.deliver
    expect(invitation).to have_received(:deliver)
  end
end

Alternative way

RSpec.describe "have_received" do
  it "passes when the message has been received" do
    # omitted code
    expect_any_instance_of(Invitation).to receive(:have_received)
    
    post create, params
    
    expect(response.status).to eq(302)
  end
end