On Sunday, February 1, 2015 at 2:17:43 AM UTC-8, Kerry Buckley wrote:
>
> I've recently discovered compound expectations in RSpec 3, which I really
> like, but I noticed a difference in output if you use them within a custom
> matcher. For example:
>
> RSpec::Matchers.define :be_acceptable do
> match do |actual|
> expect(actual).to be_even.and be > 10
> end
> end
>
> describe "Composing matchers" do
> it "works in an expectation" do
> expect(1).to be_even.and be > 10
> end
>
> it "works inside another matcher" do
> expect(1).to be_acceptable
> end
> end
>
> Both expectations work, but the second loses the detailed failure
> information:
>
> Failure/Error: expect(1).to be_even.and be > 10 expected `1.even?` to
> return true, got false ...and: expected: > 10 got: 1
> Failure/Error: expect(1).to be_acceptable expected 1 to be acceptable
>
> Is there a way to encapsulate a set of other matchers inside another
> matcher, while retaining the full failure messages?
>
> Thanks,
>
> Kerry
>
By defining a custom be_acceptable matcher, you are telling RSpec you want
the description and failure message to use “be acceptable” in the
description and failure message.
OTOH, if you simply want to use be_acceptable, and don’t care about it
actually being a custom matcher, you can define it simply as a well-named
helper method that returns the compound matcher expression:
module MatcherHelpers
def be_acceptable
be_even.and be > 10
endend
RSpec.configure do |c|
c.include MatcherHelpersend
…which will give you the exact same failure as your first example.
HTH,
Myron
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