Make mkColoredLineDiff resizable

Author: nicolasstucki

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

@@ -61,7 +61,7 @@ object DiffUtil {
     (fnd, exp, totalChange.toDouble / (expected.length + found.length))
   }
 
-  def mkColoredLineDiff(expected: String, actual: String): String = {
+  def mkColoredLineDiff(expected: String, actual: String, expectedSize: Int): String = {
     lazy val diff = {
       val tokens = splitTokens(expected, Nil).toArray
       val lastTokens = splitTokens(actual, Nil).toArray
@@ -90,9 +90,9 @@ object DiffUtil {
           DELETION_COLOR + str + ANSI_DEFAULT
       }.mkString
 
-    val pad = " " * (60 - expected.length).max(0)
+    val pad = " " * 0.max(expectedSize - expected.length)
 
-    expectedDiff + pad + "| " + actualDiff
+    expectedDiff + pad + "  |  " + actualDiff
   }
 
   def mkColoredCodeDiff(code: String, lastCode: String, printDiffDel: Boolean): String = {

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

@@ -511,8 +511,9 @@ trait ParallelTesting extends RunnerOrchestration { self =>
 
           if (outputLines.length != checkLines.length || !linesMatch) {
             // Print diff to files and summary:
+            val expectedSize = DiffUtil.EOF.length max outputLines.map(_.length).max
             val diff = (outputLines :+ DiffUtil.EOF).zip(checkLines :+ DiffUtil.EOF).map { case (act, exp) =>
-              DiffUtil.mkColoredLineDiff(exp, act)
+              DiffUtil.mkColoredLineDiff(exp, act, expectedSize)
             }.mkString("\n")
 
             val msg =