quotedOrList implementation (#126)

src/main/scala/sangria/macros/derive/DeriveEnumTypeMacro.scala

@@ -83,7 +83,7 @@ class DeriveEnumTypeMacro(context: blackbox.Context) extends {
         val configName = config.collect{case MacroRenameValue(`name`, tree, _) ⇒ tree}.lastOption
         val actualName =
           if (config.exists(_.isInstanceOf[MacroUppercaseValues]))
-            q"sangria.util.StringUtil.camelCaseToUpperCase(${configName orElse annotationName getOrElse q"$name"})"
+            q"sangria.util.StringUtil.camelCaseToUnderscore(${configName orElse annotationName getOrElse q"$name"}).toUpperCase"
           else
             q"${configName orElse annotationName getOrElse q"$name"}"
 

src/main/scala/sangria/util/StringUtil.scala

@@ -3,6 +3,21 @@ package sangria.util
 object StringUtil {
   private val camelToUpper = "_*([A-Z][a-z\\d]+)".r
 
-  def camelCaseToUpperCase(name: String) =
-    camelToUpper.findAllMatchIn(name).map(_.group(1).toUpperCase).mkString("_")
+  def camelCaseToUnderscore(name: String) =
+    camelToUpper findAllMatchIn name map (_.group(1).toLowerCase) mkString "_"
+
+  /**
+    * Given [ A, B, C ] return '"A", "B" or "C"'.
+    */
+  def quotedOrList(items: Seq[String], limit: Int = 5): String =
+    if (items.isEmpty)
+      throw new IllegalArgumentException("List is empty")
+    else {
+      val quoted = items map ("\"" + _ + "\"") take limit
+      val start = quoted dropRight 1
+      val last = quoted.last
+
+      if (start.nonEmpty) s"${start mkString ", "} or $last"
+      else last
+    }
 }

src/test/scala/sangria/util/StringUtilSpec.scala

@@ -0,0 +1,37 @@
+package sangria.util
+
+import org.scalatest.{Matchers, WordSpec}
+import sangria.util.StringUtil._
+
+class StringUtilSpec extends WordSpec with Matchers {
+  "camelCaseToUnderscore" should {
+    "convert camel-case identifiers to underscore-based one" in {
+      camelCaseToUnderscore("FooBar") should be ("foo_bar")
+      camelCaseToUnderscore("Foo1Bar") should be ("foo1_bar")
+      camelCaseToUnderscore("FooBar_Baz") should be ("foo_bar_baz")
+      camelCaseToUnderscore("_Foo_Bar_") should be ("foo_bar")
+    }
+  }
+
+  "quotedOrList" should {
+    "Does not accept an empty list" in {
+      an [IllegalArgumentException] should be thrownBy quotedOrList(Nil)
+    }
+
+    "Returns single quoted item" in {
+      quotedOrList(Seq("A")) should be ("\"A\"")
+    }
+
+    "Returns two item list" in {
+      quotedOrList(Seq("A", "B")) should be ("\"A\" or \"B\"")
+    }
+
+    "Returns comma separated many item list" in {
+      quotedOrList(Seq("A", "B", "C")) should be ("\"A\", \"B\" or \"C\"")
+    }
+
+    "Limits to five items" in {
+      quotedOrList(Seq("A", "B", "C", "D", "E", "F")) should be ("\"A\", \"B\", \"C\", \"D\" or \"E\"")
+    }
+  }
+}