Add test for --show-rendered-message flag.

Author: mrdziuban

frontend/src/test/scala/bloop/bsp/BspCompileSpec.scala

@@ -1423,4 +1423,38 @@ class BspCompileSpec(
     }
   }
 
+  test("compile and return rendered message") {
+    TestUtil.withinWorkspace { workspace =>
+      val sources = List(
+        """/main/scala/Foo.scala
+          |def foo(s: String): Int = s
+          """.stripMargin
+      )
+
+      val logger = new RecordingLogger(ansiCodesSupported = false)
+      val `A` = TestProject(workspace, "a", sources, scalaVersion = Some("3.3.7"))
+      val projects = List(`A`)
+
+      loadBspState(workspace, projects, logger) { state =>
+        val compiledState = state.compile(`A`, arguments = Some(List("--show-rendered-message")))
+        assertExitStatus(compiledState, ExitStatus.CompilationError)
+        assertNoDiff(
+          // Remove ANSI escape codes
+          compiledState.lastDiagnostics(`A`).replaceAll("\u001B\\[[;\\d]*m", ""),
+          s"""
+             |#1: task start 1
+             |  -> Msg: Compiling a (1 Scala source)
+             |  -> Data kind: compile-task
+             |#1: a/src/main/scala/Foo.scala
+             |  -> List(Diagnostic(Range(Position(0,26),Position(0,27)),Some(Error),Some(_),Some(_),-- [E007] Type Mismatch Error: $workspace/a/src/main/scala/Foo.scala:1:26  1 |def foo(s: String): Int = s   |                          ^   |                          Found:    (s : String)   |                          Required: Int   |   | longer explanation available when compiling with `-explain`,None,None,Some({"actions":[]})))
+             |  -> reset = true
+             |#1: task finish 1
+             |  -> errors 1, warnings 0
+             |  -> Msg: Compiled 'a'
+             |  -> Data kind: compile-report """.stripMargin
+        )
+      }
+    }
+  }
+
 }