预期消息

使用 expect(...).to receive(...) 在测试替身上预期消息。未满足的消息预期会在示例完成后触发失败。您也可以使用 expect(...).not_to receive(...) 设置负面消息预期。

失败的正向消息预期

假设一个名为“unfulfilled_message_expectation_spec.rb”的文件，其中包含

RSpec.describe "An unfulfilled positive message expectation" do
  it "triggers a failure" do
    dbl = double("Some Collaborator")
    expect(dbl).to receive(:foo)
  end
end

当我运行 rspec unfulfilled_message_expectation_spec.rb

那么它应该失败，并显示

  1) An unfulfilled positive message expectation triggers a failure
     Failure/Error: expect(dbl).to receive(:foo)

       (Double "Some Collaborator").foo(*(any args))
           expected: 1 time with any arguments
           received: 0 times with any arguments

通过的正向消息预期

假设一个名为“fulfilled_message_expectation_spec.rb”的文件，其中包含

RSpec.describe "A fulfilled positive message expectation" do
  it "passes" do
    dbl = double("Some Collaborator")
    expect(dbl).to receive(:foo)
    dbl.foo
  end
end

当我运行 rspec fulfilled_message_expectation_spec.rb

那么这些示例应该全部通过。

失败的负向消息预期

假设一个名为“negative_message_expectation_spec.rb”的文件，其中包含

RSpec.describe "A negative message expectation" do
  it "fails when the message is received" do
    dbl = double("Some Collaborator").as_null_object
    expect(dbl).not_to receive(:foo)
    dbl.foo
  end
end

当我运行 rspec negative_message_expectation_spec.rb

那么它应该失败，并显示

  1) A negative message expectation fails when the message is received
     Failure/Error: dbl.foo

       (Double "Some Collaborator").foo(no args)
           expected: 0 times with any arguments
           received: 1 time

通过的负向消息预期

假设一个名为“negative_message_expectation_spec.rb”的文件，其中包含

RSpec.describe "A negative message expectation" do
  it "passes if the message is never received" do
    dbl = double("Some Collaborator").as_null_object
    expect(dbl).not_to receive(:foo)
  end
end

当我运行 rspec negative_message_expectation_spec.rb

那么这些示例应该全部通过。

带自定义失败消息的失败正向消息预期

假设一个名为“example_spec.rb”的文件，其中包含

RSpec.describe "An unfulfilled positive message expectation" do
  it "triggers a failure" do
    dbl = double
    expect(dbl).to receive(:foo), "dbl never calls :foo"
  end
end

当我运行 rspec example_spec.rb --format documentation

那么输出应该包含

  1) An unfulfilled positive message expectation triggers a failure
     Failure/Error: expect(dbl).to receive(:foo), "dbl never calls :foo"
       dbl never calls :foo

带自定义失败消息的失败负向消息预期

假设一个名为“example_spec.rb”的文件，其中包含

RSpec.describe "A negative message expectation" do
  it "fails when the message is received" do
    dbl = double
    expect(dbl).not_to receive(:foo), "dbl called :foo but is not supposed to"
    dbl.foo
  end
end

当我运行 rspec example_spec.rb --format documentation

那么输出应该包含

  1) A negative message expectation fails when the message is received
     Failure/Error: dbl.foo
       dbl called :foo but is not supposed to