Rspec Allow/Expect VS Just Expect/And_Return

RSpec allow/expect vs just expect/and_return

See the classic article Mocks Aren't Stubs. allow makes a stub while expect makes a mock. That is allow allows an object to return X instead of whatever it would return unstubbed, and expect is an allow plus an expectation of some state or event. When you write

allow(Foo).to receive(:bar).with(baz).and_return(foobar_result)

... you're telling the spec environment to modify Foo to return foobar_result when it receives :bar with baz. But when you write

expect(Foo).to receive(:bar).with(baz).and_return(foobar_result) 

... you're doing the same, plus telling the spec to fail unless Foo receives :bar with baz.

To see the difference, try both in examples where Foo does not receive :bar with baz.

Rspec double expect/allow anything

allow and expect methods can be used to stub methods/set expectations on particular method. Augmenting object with null object pattern is quite different, and thus uses different method call.

Please note that you should usually not use null object in area that is tested by particular test -- it is meant to imitate some part of the system that is side effect of tested code, which cannot be stubbed easily.

Rspec allow and expect the same method with different arguments

Seems like you are missing the .with('step2', anything)

it 'should call' do

  allow(Temp::Service).to receive(:run).with('step1', anything).and_return(true)

  # Append `.with('step2', anything)` here
  expect(Temp::Service).to receive(:run).with('step2', anything) do |name, p|
    expect(name).to eq 'step2' # you might not need this anymore as it is always gonna be 'step2'
    expect(p['arg3']).not_to be_nil
  end

  Temp::Service.do_job
end

RSpec: use `receive ... exactly ... with ... and_return ...` with different `with` arguments

There's an rspec-any_of gem that allows for the following syntax by prodiding all_of argument matcher:

expect(ctx[:helpers]).to receive(:sanitize_strip).with(
  %{String\n<a href="http://localhost:3000/">description</a> <br/>and newline\n<br>}
  all_of({length: 15}, {length: nil})
)
.and_return('String descr...', 'String description and newline')
.twice

rspec, validate the actual Expectation parameter

You can use a custom matches in with() as shown in the spec docs https://relishapp.com/rspec/rspec-mocks/docs/setting-constraints/matching-arguments#using-a-custom-matcher

rspec new syntax stub method with parameters and return fix value

This is how the new syntax works:

allow(A).to receive(:next).with(1).and_return("B")

rspec and_return multiple values

Multiple-value returns are arrays:

> def f; return 1, 2; end
> f.class
 => Array 

So return an array:

f.stub!(:foo).and_return([3, 56])

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