add some checked helpers (#48)

src/main/scala/lenthall/validation/Checked.scala

@@ -0,0 +1,15 @@
+package lenthall.validation
+
+import cats.data.NonEmptyList
+import cats.syntax.either._
+import lenthall.Checked
+
+object Checked {
+  implicit class ValidCheck[A](val obj: A) extends AnyVal {
+    def validNelCheck: Checked[A] = obj.asRight[NonEmptyList[String]]
+  }
+
+  implicit class InvalidCheck(val obj: String) extends AnyVal {
+    def invalidNelCheck[A]: Checked[A] = NonEmptyList.one(obj).asLeft[A]
+  }
+}

src/test/scala/lenthall/validation/CheckedSpec.scala

@@ -0,0 +1,14 @@
+package lenthall.validation
+
+import cats.data.NonEmptyList
+import org.scalatest.{FlatSpec, Matchers}
+import lenthall.validation.Checked._
+
+class CheckedSpec extends FlatSpec with Matchers {
+  behavior of "Checked"
+
+  it should "provide helper methods" in {
+    5.validNelCheck shouldBe Right(5)
+    "argh".invalidNelCheck[Int] shouldBe Left(NonEmptyList.one("argh"))
+  }
+}