sbt#1178 format and validator

Author: Ty

src/main/scala/com/typesafe/sbt/packager/rpm/RpmMetadata.scala

@@ -224,7 +224,7 @@ case class RpmSpec(meta: RpmMetadata,
     sb append ("Release: %s\n" format meta.release)
     sb append ("Summary: %s\n" format meta.summary)
 
-    meta.epoch filter(_ >= 0) foreach{ epoch =>
+    meta.epoch filter (_ >= 0) foreach { epoch =>
       sb append ("Epoch: %d\n" format epoch)
     }
 

src/main/scala/com/typesafe/sbt/packager/rpm/RpmPlugin.scala

@@ -106,7 +106,8 @@ object RpmPlugin extends AutoPlugin {
     validatePackageValidators in Rpm := Seq(
       nonEmptyMappings((linuxPackageMappings in Rpm).value.flatMap(_.mappings)),
       filesExist((linuxPackageMappings in Rpm).value.flatMap(_.mappings)),
-      checkMaintainer((maintainer in Rpm).value, asWarning = false)
+      checkMaintainer((maintainer in Rpm).value, asWarning = false),
+      epochIsNaturalNumber((rpmEpoch in Rpm).value.getOrElse(0))
     ),
     // override the linux sourceDirectory setting
     sourceDirectory in Rpm := sourceDirectory.value,

src/main/scala/com/typesafe/sbt/packager/validation/package.scala

@@ -63,4 +63,16 @@ package object validation {
     }
   }
 
+  def epochIsNaturalNumber(epoch: Int): Validation.Validator = () => {
+    sys.error(s"Passed: $epoch")
+    if (epoch < 0) {
+      ValidationError(
+        description = s"The Epoch cannot be a negative number (found $epoch)",
+        howToFix = "Change rpmEpoch to Some(n), where n >= 0"
+      ) :: Nil
+    } else {
+      Nil
+    }
+  }
+
 }