Output from System.out doesn't get printed

[Daenyth]

I'm trying to write some cats-effect documentation using IO.println, which boils down to a System.out call. The text doesn't get output.

Input doc:

```scala mdoc
import cats.effect._
import cats.effect.unsafe.implicits.global
IO.println("text").unsafeRunSync()
```

Output doc:

```scala
import cats.effect._
import cats.effect.unsafe.implicits.global
IO.println("text").unsafeRunSync()
```

[Daenyth]

@tpolecat has a workaround using this: https://github.com/tpolecat/skunk/blob/main/modules/docs/src/main/scala/mdoc/package.scala

// Copyright (c) 2018-2021 by Rob Norris
// This software is licensed under the MIT License (MIT).
// For more information see LICENSE or https://opensource.org/licenses/MIT

package skunk

import cats.effect.IO
import cats.effect.unsafe.implicits.global

package object mdoc {

  implicit class IOOps[A](fa: IO[A]) {
    def unsafeRunSyncWithRedirect(): A = {
      val oldOut = System.out
      val newOut = Console.out // important to do this on the calling thread!
      try {
        System.setOut(newOut)
        fa.unsafeRunSync()
      } finally System.setOut(oldOut)
    }
  }
}

[keynmol]

For CE3 it's slightly simpler btw, I believe a similar approach is used in the mdoc documentation of cats effect itself: https://github.com/indoorvivants/mdoc-effect/blob/master/core/src/main/scala/captureStdOut.scala#L43-L48

[tpolecat]

CE Console uses System.out to avoid the thread affinity associated with scala.Console. I don't think there is a good solution, we just need to reach some consensus on the right workaround. Baking the above in to the CE3 runtime might end up being an ok compromise, dunno. It's all bad. /cc @djspiewak

[Daenyth]

For CE3 it's slightly simpler btw, I believe a similar approach is used in the mdoc documentation of cats effect itself: https://github.com/indoorvivants/mdoc-effect/blob/master/core/src/main/scala/captureStdOut.scala#L43-L48

Could you point out where that's done in the CE docs? I wasn't able to find anything like that, but maybe I missed it

[keynmol]

Sorry, I messed up - I meant the tests :( https://github.com/typelevel/cats-effect/blob/d9285906a0b8f3c1b902549cae2781ebc4b90ee7/tests/shared/src/test/scala/cats/effect/std/ConsoleSpec.scala#L28

The docs don't do this and that's why in a few of them there's no output - mdoc sends it to terminal during building