Add support for multi module project in runtime

scalac-scoverage-runtime/src/main/scala/scoverage/Invoker.scala

@@ -10,8 +10,8 @@ import scala.io.Source
 object Invoker {
 
   private val MeasurementsPrefix = "scoverage.measurements."
-  private val threadFile = new ThreadLocal[FileWriter]
-  private val ids = TrieMap.empty[Int, Any]
+  private val threadFiles = new ThreadLocal[TrieMap[String, FileWriter]]
+  private val ids = TrieMap.empty[(String, Int), Any]
 
   /**
    * We record that the given id has been invoked by appending its id to the coverage
@@ -34,17 +34,18 @@ object Invoker {
     // times since for coverage we only care about 1 or more, (it just slows things down to
     // do it more than once), anything we can do to help is good. This helps especially with code
     // that is executed many times quickly, eg tight loops.
-    if (!ids.contains(id)) {
+    if (!ids.contains(dataDir, id)) {
       // Each thread writes to a separate measurement file, to reduce contention
       // and because file appends via FileWriter are not atomic on Windows.
-      var writer = threadFile.get()
-      if (writer == null) {
-        val file = measurementFile(dataDir)
-        writer = new FileWriter(file, true)
-        threadFile.set(writer)
-      }
+      var files = threadFiles.get()
+      if (files == null)
+        files = TrieMap.empty[String, FileWriter]
+        threadFiles.set(files)
+
+      val writer = files.getOrElseUpdate(dataDir, new FileWriter(measurementFile(dataDir), true))
       writer.append(id.toString + '\n').flush()
-      ids.put(id, ())
+
+      ids.put((dataDir, id), ())
     }
   }
 

scalac-scoverage-runtime/src/test/scala/scoverage/InvokerMultiModuleTest.scala

@@ -0,0 +1,47 @@
+package scoverage
+
+import java.io.File
+
+import org.scalatest.{BeforeAndAfter, FunSuite}
+
+/**
+ * Verify that [[Invoker.invoked()]] can handle a multi-module project
+ */
+class InvokerMultiModuleTest extends FunSuite with BeforeAndAfter {
+
+  val measurementDir = Array(new File("invoker-test.measurement0"), new File("invoker-test.measurement1"))
+
+  before {
+    deleteMeasurementFiles()
+    measurementDir.foreach(_.mkdirs)
+  }
+
+  test("calling Invoker.invoked on with different directories puts mesurments in different directories") {
+
+    val testIds: Set[Int] = (1 to 10).toSet
+
+    testIds.map { i: Int => Invoker.invoked(i, measurementDir(i % 2).toString) }
+
+    // Verify measurements went to correct directory
+    val measurementFiles0 = Invoker.findMeasurementFiles(measurementDir(0))
+    val idsFromFile0 = Invoker.invoked(measurementFiles0).toSet
+
+    idsFromFile0 === testIds.filter { i: Int => i % 2 == 0 }
+
+    val measurementFiles1 = Invoker.findMeasurementFiles(measurementDir(0))
+    val idsFromFile1 = Invoker.invoked(measurementFiles1).toSet
+    idsFromFile1 === testIds.filter { i: Int => i % 2 == 1 }
+  }
+
+  after {
+    deleteMeasurementFiles()
+    measurementDir.foreach(_.delete)
+  }
+
+  private def deleteMeasurementFiles(): Unit = {
+    measurementDir.foreach((md) => {
+      if (md.isDirectory)
+        md.listFiles().foreach(_.delete())
+    })
+  }
+}