How do you attach the Scala Intellij debugger for tests? - scala

Question

What steps are needed to configure the IntelliJ debugger to attach to scala Play tests managed by sbt?
In IntelliJ 2019, you can attach the debugger to the sbt run command using the debug button in the sbt shell with no configuration changes.
However, the debugger does not attach to the test command.

Answer 1

Consider attaching the debugger via IntelliJ's sbt shell:
In the sbt projects tool window select checkbox Use sbt shell for builds
Open sbt shell tool window (usually found at the bottom)
Click Attach debugger to sbt shell button (the icon looks like a bug)
In the status bar it should say Connected to the target VM (see the image bellow)
Set breakpoints in your test
Execute test command in the sbt shell tool window
Debug sbt shell window should open and execution should stop at the first breakpoint.
Note if you are using Play like OP, then by default Play runs tests in forked JVM, so for the above technique to work try setting Test / fork := false in build.sbt.

Answer 2

First, you need to run your SBT with -jvm-debug [port] like:
sbt -jvm-debug 5005
Then open dialog Run/Debug Configuration and click on Remote.
On the newly created configuration set up the correct host and port (usually localhost and 5005) and click on apply.
Then when you'll just need to run this configuration and set up breakpoints. After that just run test inside SBT console.