Address feedback from discussion on Scala contributors

build.sbt

@@ -54,6 +54,9 @@ def testSetup(scalaVersion: String): Seq[Setting[_]] = {
       test in testConfig := {
         (test in Test).dependsOn(fullClasspath in testConfig).value
       },
+      testOnly in testConfig := {
+        (testOnly in Test).dependsOn(fullClasspath in testConfig).evaluated
+      },
       fullClasspath in testConfig := {
         val ci = getCompilerInterface(appConfiguration.value,
                                       scalaCompilerBridgeSource.value,

src/main/scala/sbt/errorssummary/ConciseReporter.scala

@@ -4,7 +4,7 @@ package errorssummary
 import xsbti.{Position, Reporter, Severity}
 
 import java.io.File
-import scala.Console.{BLUE, CYAN, RED, RESET, YELLOW}
+import scala.Console.{BLUE, CYAN, RED, RESET, UNDERLINED, YELLOW}
 import scala.compat.Platform.EOL
 
 /**
@@ -15,6 +15,7 @@ import scala.compat.Platform.EOL
  * @param parent Another reporter that should also receive the messages.
  */
 private class ConciseReporter(logger: Logger,
+                              enableColors: Boolean,
                               base: String,
                               parent: Option[Reporter])
     extends Reporter {
@@ -62,7 +63,7 @@ private class ConciseReporter(logger: Logger,
 
   override def log(pos: Position, msg: String, sev: Severity): Unit = {
     parent.foreach(_.log(pos, msg, sev))
-    _problems += Problem(_problems.length, sev, msg, pos)
+    _problems += Problem(_problems.length + 1, sev, msg, pos)
   }
 
   override def comment(pos: Position, msg: String): Unit =
@@ -104,7 +105,8 @@ private class ConciseReporter(logger: Logger,
    * @return The colored string.
    */
   private def colored(color: String, str: String): String =
-    s"${RESET}${color}${str}${RESET}"
+    if (enableColors) s"${RESET}${color}${str}${RESET}"
+    else str
 
   /**
    * Put a prefix `prefix` at the beginning of `paragraph`, indents all lines.
@@ -127,7 +129,9 @@ private class ConciseReporter(logger: Logger,
     val file = problem.position.pfile
     val line = problem.position.pline
     val text =
-      s"""${file}:${line}: ${problem.message}
+      s"""${colored(UNDERLINED, file)}:${colored(colorFor(problem),
+                                                 line.toString)}:
+         |${problem.message}
          |${problem.position.lineContent}
          |${problem.position.pointerSpace
            .map(sp => s"$sp^")
@@ -136,19 +140,27 @@ private class ConciseReporter(logger: Logger,
     prefixed(s"$extraSpace[${problem.id}] ", text)
   }
 
+  /**
+   * Retrieves the right color to use for `problem` based on Severity.
+   *
+   * @param problem The problem to show.
+   * @return The ANSI string to set the right color.
+   */
+  private def colorFor(problem: Problem): String =
+    problem.severity match {
+      case Severity.Info  => CYAN
+      case Severity.Error => RED
+      case Severity.Warn  => YELLOW
+    }
+
   /**
    * Shows the line at which `problem` occured and the id of the problem.
    *
    * @param problem The problem to show
    * @return A formatted string that shows the line of the problem and its id.
    */
   private def showProblemLine(problem: Problem): String = {
-    val color =
-      problem.severity match {
-        case Severity.Info  => CYAN
-        case Severity.Error => RED
-        case Severity.Warn  => YELLOW
-      }
+    val color = colorFor(problem)
     colored(color, problem.position.pline.toString) + colored(
       BLUE,
       s" [${problem.id}]")

src/main/scala/sbt/errorssummary/Plugin.scala

@@ -12,12 +12,29 @@ object Plugin extends AutoPlugin {
     inConfig(Compile)(reporterSettings) ++
       inConfig(Test)(reporterSettings)
 
+  private val insideEmacs =
+    sys.props.contains("INSIDE_EMACS")
+
+  private val inCI =
+    System.console() == null ||
+      sys.props.get("CI").exists(_ == "true") ||
+      sys.props.get("CONTINUOUS_INTEGRATION").exists(_ == "true") ||
+      sys.props.contains("BUILD_NUMBER")
+
   private val reporterSettings =
     compilerReporter in compile := {
-      val parent    = (compilerReporter in compile).value
-      val logger    = streams.value.log
-      val sourceDir = sourceDirectory.value.getAbsolutePath
-      val reporter  = new ConciseReporter(logger, sourceDir, parent)
+      val parent = (compilerReporter in compile).value
+      val logger = streams.value.log
+
+      // Disable color in Emacs and CI
+      val enableColors = !(insideEmacs || inCI)
+
+      // We don't shorten paths if we're inside Emacs
+      val sourceDir =
+        if (insideEmacs) "" else sourceDirectory.value.getAbsolutePath
+
+      val reporter =
+        new ConciseReporter(logger, enableColors, sourceDir, parent)
       Some(reporter)
     }
 }

src/test/scala/sbt/errorssummary/ConciseReporterSpec.scala

@@ -8,7 +8,7 @@ trait ConciseReporterSpec { self: CompilerSpec =>
   def collectMessagesFor[T](code: String)(
       fn: (Array[Problem], Seq[(Level.Value, String)]) => T): T = {
     val logger   = new RecordingLogger
-    val reporter = new ConciseReporter(logger, "", None)
+    val reporter = new ConciseReporter(logger, false, "", None)
     compile(reporter, code)
     reporter.printSummary()
     fn(reporter.problems, logger.getAll())