Desired Behavior

For Dune's built-in expect tests, where a test executable prints to stdout and Dune diffs the output with a .expected file, it would be useful if Dune provided an alias for each test.

Expect test diffs can be large so the ability to specify a single test would be useful. Right now, the options to execute a single expect test are either to put them in separate directories or manually define each with a rule instead of the (tests ...) stanza.

Dune already provides aliases for each cram test, so extending that feature to expect tests feels natural.

Example

Directory:

.
└── test
    ├── dune
    ├── test_1.expected
    ├── test_1.ml
    ├── test_2.expected
    └── test_2.ml

Contents of test/dune:

(tests (names test_1 test_2))

Commands:

$ dune build @test_1 # executes and diffs test_1
$ dune build @test_2 # executes and diffs test_2