Properly handle newlines in diff results

core/src/main/scala/com/softwaremill/diffx/DiffResultPrinter.scala

@@ -12,13 +12,13 @@ object DiffResultPrinter {
       case dr: DiffResultString        => s"${dr.diffs.map(ds => showIndented(ds, indent)).mkString("\n")}"
       case dr: DiffResultStringLine    => mergeChunks(dr.diffs).map(ds => showIndented(ds, indent)).mkString
       case dr: DiffResultStringWord    => mergeChunks(dr.diffs).map(ds => showIndented(ds, indent)).mkString
-      case dr: DiffResultChunk         => arrowColor("[") + showChange(s"${dr.left}", s"${dr.right}") + arrowColor("]")
-      case dr: DiffResultValue[_]      => showChange(s"${dr.left}", s"${dr.right}")
-      case dr: IdenticalValue[_]       => defaultColor(s"${dr.value}")
-      case dr: DiffResultMissing[_]    => missingColor(s"${dr.value}")
-      case dr: DiffResultMissingChunk  => missingColor(s"[${dr.value}]")
-      case dr: DiffResultAdditional[_] => additionalColor(s"${dr.value}")
-      case dr: DiffResultAdditionalChunk => additionalColor(s"[${dr.value}]")
+      case dr: DiffResultChunk         => arrowColor("[") + showChange(s"${dr.left}", s"${dr.right}", indent) + arrowColor("]")
+      case dr: DiffResultValue[_]      => showChange(s"${dr.left}", s"${dr.right}", indent)
+      case dr: IdenticalValue[_]       => defaultColor(s"${dr.value}", indent)
+      case dr: DiffResultMissing[_]    => missingColor(s"${dr.value}", indent)
+      case dr: DiffResultMissingChunk  => missingColor(s"[${dr.value}]", indent)
+      case dr: DiffResultAdditional[_] => additionalColor(s"${dr.value}", indent)
+      case dr: DiffResultAdditionalChunk => additionalColor(s"[${dr.value}]", indent)
     }
   }
 
@@ -89,12 +89,14 @@ object DiffResultPrinter {
       }
   }
 
-  private def leftColor(s: String)(implicit c: ShowConfig): String = c.left(s)
-  private def missingColor(s: String)(implicit c: ShowConfig): String = c.missing(s)
-  private def additionalColor(s: String)(implicit c: ShowConfig): String = c.additional(s)
-  private def rightColor(s: String)(implicit c: ShowConfig): String = c.right(s)
-  private def defaultColor(s: String)(implicit c: ShowConfig): String = c.default(s)
+  private def missingColor(s: String, indent: Int)(implicit c: ShowConfig): String = withColor(s, c.missing, indent)
+  private def additionalColor(s: String, indent: Int)(implicit c: ShowConfig): String = withColor(s, c.additional, indent)
+  private def defaultColor(s: String, indent: Int = 0)(implicit c: ShowConfig): String = withColor(s, c.default, indent)
   private def arrowColor(s: String)(implicit c: ShowConfig): String = c.arrow(s)
-  private def showChange(l: String, r: String)(implicit c: ShowConfig): String =
-    leftColor(l) + arrowColor(" -> ") + rightColor(r)
+  private def showChange(l: String, r: String, indent: Int)(implicit c: ShowConfig): String =
+    withColor(l, c.left, indent) + arrowColor(" -> ") + withColor(r, c.right, indent)
+
+  private def withColor(value: String, color: String => String, indent: Int): String = {
+    value.split("\n", -1).map(color(_)).mkString("\n" + " ".repeat(indent))
+  }
 }

core/src/test/scala/com/softwaremill/diffx/test/DiffResultTest.scala

@@ -168,4 +168,34 @@ class DiffResultTest extends AnyFreeSpec with Matchers {
       ).show() shouldBe "abc abc-[ ]"
     }
   }
+
+  "diff iterable output" - {
+    "it should show an indented diff for objects with multiline toString" in {
+      val john = new VerboseNonCaseClass("John", 33)
+      val mary = new VerboseNonCaseClass("Mary", 28)
+      val jane = new VerboseNonCaseClass("Jane", 5)
+      DiffResultIterable(
+        "List",
+        Map(
+          "0" -> IdenticalValue(john),
+          "1" -> DiffResultAdditional(mary),
+          "2" -> DiffResultMissing(jane),
+        )
+      ).show() shouldBe
+        """List(
+          |     0: VerboseNonCaseClass(
+          |              key:   John,
+          |              value: 33
+          |          ),
+          |     1: +VerboseNonCaseClass(
+          |          +    key:   Mary,
+          |          +    value: 28
+          |          +),
+          |     2: -VerboseNonCaseClass(
+          |          -    key:   Jane,
+          |          -    value: 5
+          |          -))""".stripMargin
+
+    }
+  }
 }

core/src/test/scala/com/softwaremill/diffx/test/examples.scala

@@ -57,3 +57,16 @@ class NonCaseClass(private val field: String) {
     }
   }
 }
+
+class VerboseNonCaseClass(private val key: String, private val value: Int) {
+  override def toString: String =
+    s"""VerboseNonCaseClass(
+       |    key:   $key,
+       |    value: $value
+       |)""".stripMargin
+
+  override def equals(obj: Any): Boolean = obj match {
+    case other: VerboseNonCaseClass => other.key == key && other.value == value
+    case _ => false
+  }
+}