Merge pull request #3353 from dotty-staging/make-vulpix-diff-readable

Make vulpix diff readable

Author: nicolasstucki

compiler/src/dotty/tools/dotc/util/DiffUtil.scala

@@ -8,10 +8,13 @@ object DiffUtil {
   private final val ANSI_DEFAULT = "\u001B[0m"
   private final val ANSI_RED = "\u001B[31m"
   private final val ANSI_GREEN = "\u001B[32m"
+  private final val ANSI_EOF = "\u001B[2m"
 
   private final val DELETION_COLOR = ANSI_RED
   private final val ADDITION_COLOR = ANSI_GREEN
 
+  val EOF = new String("EOF") // Unique string up to reference
+
   @tailrec private def splitTokens(str: String, acc: List[String] = Nil): List[String] = {
       if (str == "") {
         acc.reverse
@@ -58,22 +61,38 @@ object DiffUtil {
     (fnd, exp, totalChange.toDouble / (expected.length + found.length))
   }
 
-  def mkColoredLineDiff(expected: String, actual: String): String = {
-    val tokens = splitTokens(expected, Nil).toArray
-    val lastTokens = splitTokens(actual, Nil).toArray
-
-    val diff = hirschberg(lastTokens, tokens)
+  def mkColoredLineDiff(expected: String, actual: String, expectedSize: Int): String = {
+    lazy val diff = {
+      val tokens = splitTokens(expected, Nil).toArray
+      val lastTokens = splitTokens(actual, Nil).toArray
+      hirschberg(lastTokens, tokens)
+    }
 
-    "  |SOF\n" + diff.collect {
-      case Unmodified(str) =>
-        "  |" + str
-      case Inserted(str) =>
-        ADDITION_COLOR + "e |" + str + ANSI_DEFAULT
-      case Modified(old, str) =>
-        DELETION_COLOR + "a |" + old + "\ne |" + ADDITION_COLOR + str + ANSI_DEFAULT
-      case Deleted(str) =>
-        DELETION_COLOR + "\na |" + str + ANSI_DEFAULT
-    }.mkString + "\n  |EOF"
+    val expectedDiff =
+      if (expected eq EOF) ANSI_EOF + expected + ANSI_DEFAULT
+      else diff.collect {
+        case Unmodified(str) => str
+        case Inserted(str) =>
+          ADDITION_COLOR + str + ANSI_DEFAULT
+        case Modified(_, str) =>
+          ADDITION_COLOR + str + ANSI_DEFAULT
+        case Deleted(_) => ""
+      }.mkString
+
+    val actualDiff =
+      if (actual eq EOF) ANSI_EOF + actual + ANSI_DEFAULT
+      else diff.collect {
+        case Unmodified(str) => str
+        case Inserted(_) => ""
+        case Modified(str, _) =>
+          DELETION_COLOR + str + ANSI_DEFAULT
+        case Deleted(str) =>
+          DELETION_COLOR + str + ANSI_DEFAULT
+      }.mkString
+
+    val pad = " " * 0.max(expectedSize - expected.length)
+
+    expectedDiff + pad + "  |  " + actualDiff
   }
 
   def mkColoredCodeDiff(code: String, lastCode: String, printDiffDel: Boolean): String = {

compiler/test/dotty/tools/vulpix/ParallelTesting.scala

@@ -500,8 +500,8 @@ trait ParallelTesting extends RunnerOrchestration { self =>
       else runMain(testSource.runClassPath) match {
         case Success(_) if !checkFile.isDefined || !checkFile.get.exists => // success!
         case Success(output) => {
-          val outputLines = output.lines.toArray
-          val checkLines: Array[String] = Source.fromFile(checkFile.get).getLines().toArray
+          val outputLines = output.lines.toArray :+ DiffUtil.EOF
+          val checkLines: Array[String] = Source.fromFile(checkFile.get).getLines().toArray :+ DiffUtil.EOF
           val sourceTitle = testSource.title
 
           def linesMatch =
@@ -511,13 +511,14 @@ trait ParallelTesting extends RunnerOrchestration { self =>
 
           if (outputLines.length != checkLines.length || !linesMatch) {
             // Print diff to files and summary:
-            val diff = outputLines.zip(checkLines).map { case (act, exp) =>
-              DiffUtil.mkColoredLineDiff(exp, act)
+            val expectedSize = DiffUtil.EOF.length max checkLines.map(_.length).max
+            val diff = outputLines.padTo(checkLines.length, "").zip(checkLines.padTo(outputLines.length, "")).map { case (act, exp) =>
+              DiffUtil.mkColoredLineDiff(exp, act, expectedSize)
             }.mkString("\n")
 
             val msg =
               s"""|Output from '$sourceTitle' did not match check file.
-                  |Diff ('e' is expected, 'a' is actual):
+                  |Diff (expected on the left, actual right):
                   |""".stripMargin + diff + "\n"
             echo(msg)
             addFailureInstruction(msg)