Add test util to check neg macro tests

main-settings/src/test/scala/sbt/std/TestUtil.scala

@@ -0,0 +1,56 @@
+/*
+ * This file has been copy-pasted from spores.
+ * https://github.com/scalacenter/spores/blob/master/core/src/test/scala/scala/spores/TestUtil.scala
+ */
+
+package sbt.std
+
+import scala.reflect._
+
+object TestUtil {
+  import scala.language.postfixOps
+  import tools.reflect.{ ToolBox, ToolBoxError }
+
+  def intercept[T <: Throwable: ClassTag](test: => Any): T = {
+    try {
+      test
+      throw new Exception(s"Expected exception ${classTag[T]}")
+    } catch {
+      case t: Throwable =>
+        if (classTag[T].runtimeClass != t.getClass) throw t
+        else t.asInstanceOf[T]
+    }
+  }
+
+  def eval(code: String, compileOptions: String = ""): Any = {
+    val tb = mkToolbox(compileOptions)
+    tb.eval(tb.parse(code))
+  }
+
+  def mkToolbox(compileOptions: String = ""): ToolBox[_ <: scala.reflect.api.Universe] = {
+    val m = scala.reflect.runtime.currentMirror
+    import scala.tools.reflect.ToolBox
+    m.mkToolBox(options = compileOptions)
+  }
+
+  lazy val toolboxClasspath: String = {
+    val resource = getClass.getClassLoader.getResource("toolbox.classpath")
+    val classpathFile = scala.io.Source.fromFile(resource.toURI)
+    val completeSporesCoreClasspath = classpathFile.getLines.mkString
+    completeSporesCoreClasspath
+  }
+
+  def expectError(errorSnippet: String,
+                  compileOptions: String = "-Xmacro-settings:debug-spores",
+                  baseCompileOptions: String = s"-cp $toolboxClasspath")(code: String) {
+    val errorMessage = intercept[ToolBoxError] {
+      eval(code, s"$compileOptions $baseCompileOptions")
+    }.getMessage
+    val userMessage =
+      s"""
+         |FOUND: $errorMessage
+         |EXPECTED: $errorSnippet
+      """.stripMargin
+    assert(errorMessage.contains(errorSnippet), userMessage)
+  }
+}