improvement: Add location to failure to help mark it in VS Code

Author: tgodzik

modules/core/src/main/scala/ch/epfl/scala/debugadapter/testing/TestSuiteEventHandler.scala

@@ -35,13 +35,21 @@ object TestSuiteEventHandler {
         case Status.Failure =>
           val failedMsg =
             TestUtils.printThrowable(e.throwable()).getOrElse("")
+          val location = if (e.throwable().isDefined()) {
+            val throwable = e.throwable().get.getStackTrace().headOption
+            throwable.map(stackElement =>
+              new SingleTestResult.Location(stackElement.getFileName(), stackElement.getLineNumber())
+            )
+          } else {
+            None
+          }
           val formatted =
             TestSuiteEventHandler.formatError(
               name,
               failedMsg,
               indentSize = 0
             )
-          SingleTestResult.Failed(name, e.duration, formatted)
+          SingleTestResult.Failed(name, e.duration, formatted, location)
         case _ =>
           SingleTestResult.Skipped(name)
       }

modules/core/src/main/scala/ch/epfl/scala/debugadapter/testing/TestSuiteSummary.scala

@@ -36,14 +36,20 @@ object SingleTestResult {
     def apply(testName: String): Skipped = new Skipped("skipped", testName)
   }
 
+  final class Location(
+      val file: String,
+      val line: Int
+  )
+
   final class Failed private (
       val kind: String,
       val testName: String,
       val duration: Long,
-      val error: String
+      val error: String,
+      val location: Option[Location]
   ) extends SingleTestSummary
   object Failed {
-    def apply(testName: String, duration: Long, error: String): Failed =
-      new Failed("failed", testName, duration, error)
+    def apply(testName: String, duration: Long, error: String, location: Option[Location] = None): Failed =
+      new Failed("failed", testName, duration, error, location)
   }
 }