Add main classes

src/sbt-test/projectMatrix/native/app/src/main/scala/App.scala

@@ -0,0 +1,8 @@
+package a
+
+object App {
+  def main(args: Array[String]): Unit = {
+    val a = new Core
+    println(s"Hello, world! ${a}")
+  }
+}

src/sbt-test/projectMatrix/native/build.sbt

@@ -5,13 +5,15 @@
 
 lazy val core = (projectMatrix in file("core"))
   .settings(
-    name := "core"
+    name := "core",
+    mainClass in (Compile, run) := Some("a.CoreMain")
   )
   .nativePlatform(scalaVersions = Seq("2.11.12", "2.11.11"))
 
 lazy val app = (projectMatrix in file("app"))
   .dependsOn(core)
   .settings(
-    name := "app"
+    name := "app",
+    mainClass in (Compile, run) := Some("a.App")
   )
   .nativePlatform(scalaVersions = Seq("2.11.12"))

src/sbt-test/projectMatrix/native/core/src/main/scala/CoreMain.scala

@@ -0,0 +1,6 @@
+package a
+
+object CoreMain {
+  def main(args: Array[String]): Unit = {
+  }
+}