How do I expect to receive a message (maybe multiple times) and the arguments I specified have to be provided once?

expect_to_receive_spec.rb

class MyWorker
  def self.perform_at(timestamp, job_name)
  end
end

describe 'expecting multiple calls to same method' do
  it 'works if only one call is made to the method' do
    time_now = Time.now

    expect(MyWorker).to receive(:perform_at).with(time_now, 'dowork')

    MyWorker.perform_at(time_now, 'dowork')
  end

  it 'does not work if we have multiple method calls we want to ignore' do
    time_now = Time.now

    expect(MyWorker).to receive(:perform_at).with(time_now, 'dowork')

    MyWorker.perform_at(time_now, 'dowork')
    MyWorker.perform_at(time_now + 60 * 60, 'dowork')
  end
end

output.txt

% bundle exec rspec expect_to_receive_spec.rb
.F

Failures:

  1) expecting multiple calls to same method does not work if we have multiple method calls we want to ignore
     Failure/Error: MyWorker.perform_at(time_now + 60 * 60, 'dowork')

       #<MyWorker (class)> received :perform_at with unexpected arguments
         expected: (2016-02-02 10:33:39.605657000 +0100, "dowork")
              got: (2016-02-02 11:33:39.605657000 +0100, "dowork")
       Diff:
       @@ -1,2 +1,2 @@
       -[2016-02-02 10:33:39.605657000 +0100, "dowork"]
       +[2016-02-02 11:33:39.605657000 +0100, "dowork"]
     # ./expect_to_receive_spec.rb:21:in `block (2 levels) in <top (required)>'

Finished in 0.0224 seconds (files took 0.0785 seconds to load)
2 examples, 1 failure

Failed examples:

rspec ./expect_to_receive_spec.rb:15 # expecting multiple calls to same method does not work if we have multiple method calls we want to ignore

This fixes it:

  it 'does not work if we have multiple method calls we want to ignore' do
    time_now = Time.now

    # Here is the fix:
    allow(MyWorker).to receive(:perform_at)

    expect(MyWorker).to receive(:perform_at).with(time_now, 'dowork').once

    # The order of these calls is random
    MyWorker.perform_at(time_now + 2 * 60 * 60, 'dowork')
    MyWorker.perform_at(time_now, 'dowork')
    MyWorker.perform_at(time_now + 1 * 60 * 60, 'dowork')
  end