Changed createTeskTasks in TestFramework.scala to reuse TestRunner instance when running different TestDefinition.

sbt/src/sbt-test/tests/single-runner/build.sbt

@@ -0,0 +1,5 @@
+scalaVersion := "2.10.1"
+
+libraryDependencies += "org.scalatest" %% "scalatest" % "2.0.M6-SNAP15"
+
+testOptions in Test += Tests.Argument("-r", "custom.CustomReporter")

sbt/src/sbt-test/tests/single-runner/src/main/scala/custom/CustomReporter.scala

@@ -0,0 +1,28 @@
+package custom
+
+import java.io._
+import org.scalatest._
+import events._
+
+class CustomReporter extends Reporter {
+
+	private def writeFile(filePath: String, content: String) {
+		val file = new File(filePath)
+		val writer = 
+			if (!file.exists)
+				new FileWriter(new File(filePath))
+			else
+				new FileWriter(new File(filePath + "-2"))
+		writer.write(content)
+		writer.flush()
+		writer.close()
+	}
+
+	def apply(event: Event) {
+		event match {
+			case runStarting: RunStarting => writeFile("target/RunStarting", "RunStarting")
+			case runCompleted: RunCompleted => writeFile("target/RunCompleted", "RunCompleted")
+			case _ =>
+		}
+	}
+}

sbt/src/sbt-test/tests/single-runner/src/test/scala/com/test/TestSpec.scala

@@ -0,0 +1,12 @@
+package com.test
+
+import org.scalatest.Spec
+
+class TestSpec extends Spec {
+
+	def `TestSpec-test-1 ` {}
+
+	def `TestSpec-test-2 ` {}
+	
+	def `TestSpec-test-3 ` {}
+}

sbt/src/sbt-test/tests/single-runner/src/test/scala/com/test/TestSpec2.scala

@@ -0,0 +1,12 @@
+package com.test
+
+import org.scalatest.Spec
+
+class TestSpec2 extends Spec {
+
+	def `TestSpec2-test-1 ` {}
+
+	def `TestSpec2-test-2 ` {}
+	
+	def `TestSpec2-test-3 ` {}
+}

sbt/src/sbt-test/tests/single-runner/test

@@ -0,0 +1,13 @@
+#This test that the framework will only use a single runner instance to execute all tests.
+#Because ScalaTest's runner will report RunStarting when the run start, a CustomReporter is 
+#used to report expected ScalaTest's RunStarting event by writing out to target/, it is then 
+#used to check for their existence, and if the expected event is fired > 1 (which is unexpected), 
+#a xxxx-2 file will be written, thus here we also check for 'absent' of such file.
+
+> clean
+
+> test
+
+$ exists target/RunStarting
+
+$ absent target/RunStarting-2

testing/src/main/scala/sbt/TestFramework.scala

@@ -184,6 +184,12 @@ object TestFramework
 	private def createTestTasks(loader: ClassLoader, tests: Map[Framework, (Set[TestDefinition], Seq[String])], ordered: Seq[TestDefinition], log: Logger, listeners: Seq[TestReportListener]) =
 	{
 		val testsListeners = listeners collect { case tl: TestsListener => tl }
+
+		val runnerMap = 
+			tests map { case (framework, (testDefinitions, testArgs)) =>
+				(framework, new TestRunner(framework, loader, testArgs.toArray, listeners, log))
+			}
+		
 		def foreachListenerSafe(f: TestsListener => Unit): () => Unit = () => safeForeach(testsListeners, log)(f)
 		
 			import TestResult.{Error,Passed,Failed}
@@ -191,13 +197,12 @@ object TestFramework
 		val startTask = foreachListenerSafe(_.doInit)
 		val testTasks =
 			tests flatMap { case (framework, (testDefinitions, testArgs)) =>
-			
-					val runner = new TestRunner(framework, loader, testArgs.toArray, listeners, log)
-					for(testDefinition <- testDefinitions) yield
-					{
-						val runTest = () => withContextLoader(loader) { runner.run(testDefinition) }
-						(testDefinition.name, runTest)
-					}
+				val runner = runnerMap(framework)
+				for(testDefinition <- testDefinitions) yield
+				{
+					val runTest = () => withContextLoader(loader) { runner.run(testDefinition) }
+					(testDefinition.name, runTest)
+				}
 			}
 
 		val endTask = (result: TestResult.Value) => foreachListenerSafe(_.doComplete(result))