Improve error messaging.

modules/core/src/main/scala/com/siriusxm/snapshot4s/ErrorMessages.scala

@@ -0,0 +1,22 @@
+/*
+ * Copyright 2024 SiriusXM
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package snapshot4s
+
+private object ErrorMessages {
+  val nonExistent: String = "Snapshot does not exist. Run 'sbt snapshot4sPromote' to create it."
+  val failure: String     = "Snapshot not equal. Run 'sbt snapshot4sPromote' to update it."
+}

modules/munit/src/main/scala/com/siriusxm/snapshot4s/munit/MunitResultLike.scala

@@ -32,7 +32,7 @@ private object MunitResultLike {
   private def resultToAssertion[A](result: Result[A], loc: Location): Unit = {
     result match {
       case _: Result.Success[?]     => ()
-      case _: Result.NonExistent[?] => throw Assertions.fail("Snapshot does not exist.")(loc)
+      case _: Result.NonExistent[?] => throw Assertions.fail(ErrorMessages.nonExistent)(loc)
       case Result.Failure(found, snapshot) =>
         throw Assertions.fail(diffReport(found.toString, snapshot.toString))(loc)
     }
@@ -44,6 +44,6 @@ private object MunitResultLike {
       obtained = found,
       expected = expected
     )
-    diff.createReport("Snapshot not equal", printObtainedAsStripMargin = false)
+    diff.createReport(ErrorMessages.failure, printObtainedAsStripMargin = false)
   }
 }

modules/scalatest/src/main/scala/com/siriusxm/snapshot4s/scalatest/ScalaTestResultLike.scala

@@ -44,7 +44,7 @@ private object ScalaTestResultLike {
       case _: Result.Success[?] => Succeeded
       case _: Result.NonExistent[?] =>
         throw new TestFailedException(
-          _ => Some("Snapshot does not exist."),
+          _ => Some(ErrorMessages.nonExistent),
           cause = None,
           posOrStackDepthFun = Left(pos),
           payload = None,
@@ -53,7 +53,7 @@ private object ScalaTestResultLike {
       case Result.Failure(found, snapshot) =>
         val diff = prettifier(found, snapshot)
         throw new TestFailedException(
-          _ => Some(s"Snapshots not equal. Expected: ${diff.right}, but got ${diff.left}"),
+          _ => Some(s"${ErrorMessages.failure} Expected: ${diff.right}, but got ${diff.left}"),
           cause = None,
           posOrStackDepthFun = Left(pos),
           payload = None,

modules/weaver/src/main/scala/com/siriusxm/snapshot4s/weaver/Diff.scala

@@ -16,6 +16,8 @@
 
 package snapshot4s.weaver
 
+import snapshot4s.ErrorMessages
+
 private object Diff {
 
   import munit.diff.Diff
@@ -25,6 +27,6 @@ private object Diff {
       obtained = found,
       expected = expected
     )
-    diff.createReport("Snapshot not equal", printObtainedAsStripMargin = false)
+    diff.createReport(ErrorMessages.failure, printObtainedAsStripMargin = false)
   }
 }

modules/weaver/src/main/scala/com/siriusxm/snapshot4s/weaver/WeaverResultLike.scala

@@ -20,7 +20,7 @@ import _root_.weaver.{AssertionException, Expectations, SourceLocation}
 import cats.data.{NonEmptyList, Validated}
 import cats.effect.IO
 
-import snapshot4s.{Result, ResultLike}
+import snapshot4s.{ErrorMessages, Result, ResultLike}
 
 object WeaverResultLike {
 
@@ -40,7 +40,7 @@ object WeaverResultLike {
       case _: Result.NonExistent[?] =>
         Expectations(
           Validated.invalidNel[AssertionException, Unit](
-            AssertionException("Snapshot does not exist.", NonEmptyList.of(loc))
+            AssertionException(ErrorMessages.nonExistent, NonEmptyList.of(loc))
           )
         )
       case Result.Failure(found, snapshot) =>