Condense built-in and DSL RSpec matcher inspection output

[jas14]

Problem

In diff output, some RSpec matchers, such as custom DSL-defined matchers and built-ins like be_a, are treated as default objects. This means that their fully-qualified class names and all instance variables are recursively printed, which can make the output quite verbose! Here's a very small example spec:

expected = hash_including(number: be_a(Numeric))
actual = {number: 4}
expect(actual).not_to match(expected)

which outputs the following diff:

                {
              -   number: #<RSpec::Matchers::BuiltIn::BeAKindOf:0x00000001062308f0 {
              -     @actual="not a number",
              -     @expected=Numeric
              -   }>
              +   number: "not a number"
                }

You can imagine this could get much longer with more complex expectations.

Solution

Use the matcher's description on inspection. For the case above, this results in the following:

                {
              -   number: (be a kind of Numeric)
              +   number: "not a number"
                }

[mcmire]

Hi @jas14! Thanks for the PR. Sorry for the delay in reviewing, I'm slowly getting back to this library. Just had a few comments.

[mcmire]

Thanks so much!

[mcmire]

I updated the inspector you added to also consider custom-from-scratch matchers. This is included in v0.11.0. Thanks again!