More test cases

Author: note

modules/dhallj-magnolia/src/main/scala-3/pl/msitko/dhallj/generic/Errors.scala

@@ -0,0 +1,8 @@
+package pl.msitko.dhallj.generic
+
+import org.dhallj.codec.DecodingFailure
+import org.dhallj.core.Expr
+
+final case class MissingRecordField(override val target: String, missingFieldName: String, override val value: Expr)
+    extends DecodingFailure(target, value):
+  override def toString: String = s"Missing record field '$missingFieldName' when decoding $target"

modules/dhallj-magnolia/src/main/scala-3/pl/msitko/dhallj/generic/decoder/semiauto.scala

@@ -7,13 +7,9 @@ import org.dhallj.ast.*
 import org.dhallj.codec.{Decoder, DecodingFailure, Encoder}
 import org.dhallj.codec.Decoder.Result
 import org.dhallj.core.Expr
-import pl.msitko.dhallj.generic.Extractors
+import pl.msitko.dhallj.generic.{Extractors, MissingRecordField}
 import scala.deriving.Mirror
 
-final case class MissingRecordField(override val target: String, missingFieldName: String, override val value: Expr)
-    extends DecodingFailure(target, value):
-  override def toString: String = s"Missing record field '$missingFieldName' when decoding $target"
-
 object semiauto:
 
   inline def deriveDecoder[T](using m: Mirror.Of[T]): Decoder[T] =

modules/dhallj-magnolia/src/test/scala/pl/msitko/dhallj/generic/decoder/DecoderSpec.scala

@@ -3,6 +3,7 @@ package pl.msitko.dhallj.generic.decoder
 import org.dhallj.codec.{Decoder, Encoder}
 import org.dhallj.codec.syntax._
 import org.dhallj.syntax._
+import pl.msitko.dhallj.generic.MissingRecordField
 import pl.msitko.dhallj.generic.example.akka.OnOrOff.Off
 import pl.msitko.dhallj.generic.example.akka.{Akka, Http, OnOrOff, OnOrOff2, Preview, Server}
 import pl.msitko.dhallj.generic.example.{AppConfig, DbConfig, Error, Error1, Error2, Errors, Fixtures, StatusCode}
@@ -60,6 +61,19 @@ trait DecoderSpec { self: munit.FunSuite with Fixtures =>
     assertEquals(decoded, Errors(List(Error1("abc"), Error2(code = 123, code2 = 456))))
   }
 
+  test("Return MissingRecordField") {
+    val in =
+      """
+        |let Error = < Error1 : { msg : Text } | Error2 : { code : Natural, code2 : Natural } >
+        |in { errors = [Error.Error1 { msg = "abc"}, Error.Error2 { code2 = 456 }] }
+        |""".stripMargin
+
+    val res = in.parseExpr.getOr("Parsing failed").normalize().as[Errors]
+
+    val Left(mrf: MissingRecordField) = res
+    assertEquals(mrf.missingFieldName, "code")
+  }
+
   test("Load union with empty parameter list as case object") {
     val decoded =
       """