> Short version: I think it's a good idea. I don't know of anything like
> that, yet. I'm interested in BDD, but not so much a Gherkin style DSL.
Yeah, I currently have no plans to implement something like Gherkin. All I care
about for the time being is spec-style `describe`, `context`, `it`, and
similar. I don’t really use Cucumber for much, but it would obviously be
possible to build a DSL on top of a spec-style framework.
> Out of curiosity, what are you looking to test? If it's an HTTP api, I've got
> a ton of useful testing tools for that that I was just thinking of making
> into a package.
It’s nothing HTTP-related, just some plain old Racket code. I’m really just
interested in having the ability to write spec-style tests in general. That
said, I’m sure it would be nice to have that sort of thing in a package,
anyway, so I’d still be interested to see what you have!
Also, since Sam pointed out on IRC that some people might not know what BDD is,
I’ll include a brief demonstration of what I’d sort of like to build. It’s
mostly just a different API for writing tests that tries to be a little more
declarative. For example, testing the `+` function might look like this:
(describe "+"
(context "when a single argument is provided"
(it "is the identity"
(expect (+ 1) (to equal? 1))
(expect (+ -1) (to equal? -1))))
(context "when multiple arguments are provided"
(it "adds numbers"
(expect (+ 1 2) (to equal? 3))
(expect (+ 1 -2) (to equal? -1)))))
If a test fails, it provides some nicely-formatted information about the test
and its context. For example, consider adding the following bogus test:
(describe "+"
(context "when a single argument is provided"
(it "is the identity"
(expect (+ 1) (to equal? 1))
(expect (+ -1) (to equal? 1)))) ; oops, typo
(context "when multiple arguments are provided"
(it "adds numbers"
(expect (+ 1 2) (to equal 3))
(expect (+ 1 -2) (to equal -1)))
(it "returns a positive number" ; this is just wrong
(expect (+ 3 -5) (to be positive?)))))
That might cause the following output:
+
├── when a single argument is provided
│ ✘ is the identity
│
└── when multiple arguments are provided
✔︎ adds numbers
✘ returns a positive number
Failures:
1) + is the identity when a single argument is provided
Expectation: (expect (+ -1) (to equal? 1))
Expected: 1
Got: -1
; ./sample-spec.rkt:12:6
2) + returns a positive number when multiple arguments are provided
Expectation: (expect (+ 3 -5) (to be positive?))
Expected: value that satisfies ‘positive?’
Got: -2
; ./sample-spec.rkt:18:6
3 examples, 2 failures, 0 pending
The output format and the expectation syntax is entirely theoretical and
subject to change, but that’s the basic idea. The good news is, I think all the
basic operations can be defined in terms of existing RackUnit constructs, so
the only difficulties would be implementing the output format and the
expectations system. Ideally, though, this would provide some more semantic
information both in how tests are written and in test failure messages.
Alexis
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