Merge pull request #44 from kciesielski/handle-empty-diff

Handle empty diff

Author: adamw

model/src/main/scala/com/softwaremill/clippy/StringDiff.scala

@@ -17,18 +17,25 @@ class StringDiff(expected: String, actual: String, color: String => String) {
   private def markDiff(source: String) = {
     val prefix = findCommonPrefix()
     val suffix = findCommonSuffix()
-    val diff = color(source.substring(prefix.length, source.length - suffix.length))
-    prefix + diff + suffix
+    if (overlappingPrefixSuffix(source, prefix, suffix))
+      source
+    else {
+      val diff = color(source.substring(prefix.length, source.length - suffix.length))
+      prefix + diff + suffix
+    }
   }
 
+  private def overlappingPrefixSuffix(source: String, prefix: String, suffix: String) =
+    prefix.length + suffix.length >= source.length
+
   def findCommonPrefix(expectedStr: String = expected, actualStr: String = actual): String = {
     val prefixChars = expectedStr.zip(actualStr).takeWhile(Function.tupled(_ == _)).map(_._1)
 
     val lastSeparatorIndex = prefixChars.lastIndexWhere(isSeparator)
-    val prefixStartIndex = if (lastSeparatorIndex == -1) 0 else lastSeparatorIndex + 1
+    val prefixEndIndex = if (lastSeparatorIndex == -1) 0 else lastSeparatorIndex + 1
 
-    if (prefixChars.nonEmpty && prefixStartIndex < prefixChars.length)
-      prefixChars.mkString.substring(0, prefixStartIndex)
+    if (prefixChars.nonEmpty && prefixEndIndex < prefixChars.length)
+      prefixChars.mkString.substring(0, prefixEndIndex)
     else {
       prefixChars.mkString
     }

model/src/test/scala/com/softwaremill/clippy/StringDiffTest.scala

@@ -12,7 +12,8 @@ class StringDiffTest extends FlatSpec with Matchers {
     ("Super[String, String]", "Super[Option[String], String]", "expected Super[" + S + "String" + E + ", String] but was Super[" + S + "Option[String]" + E + ", String]"),
     ("Cool[String, String]", "Super[Option[String], String]", "expected " + S + "Cool[String" + E + ", String] but was " + S + "Super[Option[String]" + E + ", String]"),
     ("(String, String)", "Super[Option[String], String]", "expected " + S + "(String, String)" + E + " but was " + S + "Super[Option[String], String]" + E),
-    ("Map[Long, Double]", "Map[String, Double]", "expected Map[" + S + "Long" + E + ", Double] but was Map[" + S + "String" + E + ", Double]")
+    ("Map[Long, Double]", "Map[String, Double]", "expected Map[" + S + "Long" + E + ", Double] but was Map[" + S + "String" + E + ", Double]"),
+    ("(Int, Int, Float, Int, Char)", "(Int, Int, Int, Char)", "expected (Int, Int, " + S + "Float" + E + ", Int, Char) but was (Int, Int, Int, Char)")
   )
 
   "StringDiff" should "diff" in {