Re: [best practice] we should use `check` or `require` instead of `echo` + `discard` magic in tests

[GULPF]

I think most new tests use `doAssert` instead of `echo`. But even `doAssert` 
leads to a terrible testing experience. If the test is `doAssert x == y` you 
have no way of knowing the values of `x` and `y` when the test fails. Another 
issue is that `doAssert` always exists at the first failure. The `unittest` 
module fixes both of these issues, but I think it will be hard to convince Araq 
that it should be used more :-)