Unit test for dependency extraction from macro applications

Add a unit test which checks whether we capture dependencies introduced
by arguments to macros. Those dependencies are special because macros
get expanded during type checking and arguments to macros are not visible
during regular tree walk.

compile/interface/src/test/scala/xsbt/DependencySpecification.scala

@@ -65,6 +65,19 @@ class DependencySpecification extends Specification {
 		inheritance('D) === Set('A, 'C)
 	}
 
+	"Extracted source dependencies from macro arguments" in {
+		val sourceDependencies = extractSourceDependenciesFromMacroArgument
+		val memberRef = sourceDependencies.memberRef
+		val inheritance = sourceDependencies.inheritance
+
+		memberRef('A) === Set('B, 'C)
+		inheritance('A) === Set.empty
+		memberRef('B) === Set.empty
+		inheritance('B) === Set.empty
+		memberRef('C) === Set.empty
+		inheritance('C) === Set.empty
+	}
+
 	private def extractSourceDependenciesPublic: ExtractedSourceDependencies = {
 		val srcA = "class A"
 		val srcB = "class B extends D[A]"
@@ -109,4 +122,25 @@ class DependencySpecification extends Specification {
 			compilerForTesting.extractDependenciesFromSrcs('A -> srcA, 'B -> srcB, 'C -> srcC, 'D -> srcD)
 		sourceDependencies
 	}
+
+	private def extractSourceDependenciesFromMacroArgument: ExtractedSourceDependencies = {
+		val srcA = "class A { println(B.printTree(C.foo)) }"
+		val srcB = """
+			|import scala.language.experimental.macros
+			|import scala.reflect.macros._
+			|object B {
+			|  def printTree(arg: Any) = macro printTreeImpl
+			|  def printTreeImpl(c: Context)(arg: c.Expr[Any]): c.Expr[String] = {
+			|    val argStr = arg.tree.toString
+			|    val literalStr = c.universe.Literal(c.universe.Constant(argStr))
+			|    c.Expr[String](literalStr)
+			|  }
+			|}""".stripMargin
+		val srcC = "object C { val foo = 1 }"
+
+		val compilerForTesting = new ScalaCompilerForUnitTesting(nameHashing = true)
+		val sourceDependencies =
+			compilerForTesting.extractDependenciesFromSrcs(List(Map('B -> srcB, 'C -> srcC), Map('A -> srcA)))
+		sourceDependencies
+	}
 }