ScalaTest

Add the Difflicious sbt plugin to project/plugins.sbt:

addSbtPlugin("com.github.jatcwang" % "sbt-difflicious" % "0.7.0-M2")

Then add the ScalaTest integration to build.sbt:

"com.github.jatcwang" %% "difflicious-scalatest" % "0.7.0-M2" % Test

Tests should be run with the -oW option to disable ScalaTest from coloring test failures all red as it interferes with difflicious color display.

testOnly -- -oW

Here's an example of what a test using difflicious looks like:

import org.scalatest.funsuite.AnyFunSuite
import difflicious.scalatest.ScalatestDiff.*
import difflicious.Differ

class MyTest extends AnyFunSuite {
  test("a == b") { 
    Differ[Int].assertNoDiff(1, 2)
  }
}

The sbt plugin registers Difflicious' ScalaTest reporter, which writes reports for failed diffs. You can explore them with Diff Viewer UI / CLI.