Is there a way to chain multiples Fixtures?

[crakjie]

In my project I have different kind of fixture.

Some create client for one database, some create client for http connection.

They are widely used but most of the time independently.

Know I would like to create both clients do some initialization calls and uninitialized after the math.

Here an exemple with cats Ressource to ilustrate.

for { 
     dbClient <- DbRessource()
     httpClient <- HttpRessource()
     localFixture <- LocalRessouce(dbClient, httpClient)
}
yield localFixture

Currently the only way I see this possible with munit is to re-implement the content of DbRessource and HttpRessource into LocalRessouce fixture. Which is doing a lot code duplication when there is a lot of tests with different localFixture.

I did not saw solution for this problem in the documentation.

[tschuchortdev]

I can tell you how I do it: I simply don't use the munit Fixture mechanism. I have my own Fixture class that registers itself with the test suite when created but is initialized lazily. Since all the fixture instances are lazy, they can reference each other however they want and the initialization order is figured out automatically:

class MySuite extends CatsEffectSuite with MyFixtureSupport {
    val dbFixture = super.registerFixture(Fixture.fromResource(DbResource()))
    val httpClientFixture = super.registerFixture(Fixture.fromAutocloseable(HttpClient()))
    val localFixture = super.registerFixture(Fixture.fromResource(for {
        db <- dbFixture()
        httpClient <- httpClientFixture()
        r <- LocalResource(db, httpClient)
     } yield r))

   test("foo bar")(for {
      l <- localFixture()
      ....
   } yield ())
}

MyFixtureSupport overrides beforeAll and afterAll and executes the fixture initializers/finalizers there. registerFixture puts all the fixtures into a list in MyFixtureSupport. You can implement it so that fixtures are only initialized once used or you can simply initialize the whole list in beforeAll. It doesn't matter what order the list is in since any fixture will always initialize dependency fixtures before itself.