add tests for type and constraint defined outside of source

integrations/iron/src/test/scala-3/com/example/RefinedString.scala

@@ -0,0 +1,25 @@
+package com.example
+
+import io.github.iltotore.iron.*
+import sttp.tapir.Validator
+import sttp.tapir.codec.iron.PrimitiveValidatorForPredicate
+import sttp.tapir.codec.iron.ValidatorForPredicate
+
+final class RefinedStringConstraint
+
+object RefinedStringConstraint {
+
+  given Constraint[String, RefinedStringConstraint] with {
+
+    override inline def test(value: String): Boolean = value.nonEmpty
+
+    override inline def message: String = "Should not be empty"
+  }
+
+  given PrimitiveValidatorForPredicate[String, RefinedStringConstraint] =
+    ValidatorForPredicate.fromPrimitiveValidator(Validator.pattern[String]("^.+"))
+}
+
+opaque type RefinedString = String :| RefinedStringConstraint
+
+object RefinedString extends RefinedTypeOps[String, RefinedStringConstraint, RefinedString]

integrations/iron/src/test/scala-3/sttp/iron/codec/iron/TapirCodecIronTestScala3.scala

@@ -18,6 +18,9 @@ import io.github.iltotore.iron.constraint.all.*
 import sttp.tapir.Validator
 import sttp.tapir.ValidationError
 
+import com.example.RefinedString
+import com.example.RefinedStringConstraint
+
 class TapirCodecIronTestScala3 extends AnyFlatSpec with Matchers {
 
   val schema: Schema[Double :| Positive] = summon[Schema[Double :| Positive]]
@@ -321,4 +324,11 @@ class TapirCodecIronTestScala3 extends AnyFlatSpec with Matchers {
     summon[Schema[NewtypeInt]]
     summon[Codec[String, NewtypeInt, TextPlain]]
 
+  "Instances for opaque refined type defined outside of source" should "be correctly derived" in:
+    summon[Schema[RefinedString]]
+    summon[Codec[String, RefinedString, TextPlain]]
+
+  "Instance of validator for constraint defined outside of source" should "be correctly derived" in:
+    summon[PrimitiveValidatorForPredicate[String, RefinedStringConstraint]]
+
 }