[BUG] Default value for enumeratum enums is not added to OpenAPI schema

[chessman]

Tapir version: 0.20.0-M6

Scala version: 2.12.15

Describe the bug

When I specify a default value for a string using annotations, it is added as a default value in yaml. But it is not happening in case of enumeratum.

How to reproduce?

import enumeratum._
import io.circe.generic.auto._
import sttp.tapir.Schema.annotations.default
import sttp.tapir._
import sttp.tapir.codec.enumeratum._
import sttp.tapir.docs.openapi.OpenAPIDocsInterpreter
import sttp.tapir.generic.auto._
import sttp.tapir.json.circe._
import sttp.tapir.openapi.OpenAPI
import sttp.tapir.openapi.circe.yaml._

object TapirTest extends App {

  sealed trait E extends EnumEntry
  object E extends Enum[E] with CirceEnum[E] {
    case object Value extends E
    override def values: scala.collection.immutable.IndexedSeq[E] = findValues
  }

  case class Input(
    @default(E.Value)
    e: E,
    @default("it works for strings")
    string: String
  )

  val testEndpoint = endpoint.in(jsonBody[Input])

  val docs: OpenAPI = OpenAPIDocsInterpreter().toOpenAPI(testEndpoint, "My Test", "1.0")
  println(docs.toYaml)
}

You can see that in the following output there is no default value for E:

  ...
  schemas:
    E:
      type: string
      enum:
      - Value
    Input:
      type: object
      properties:
        e:
          $ref: '#/components/schemas/E'
        string:
          type: string
          default: it works for strings

[mkrzemien]

An encoded version (the one included in the documentation) of a default value is automatically derived only in case of basic types (like strings or numbers). It is currently not supported for complex types like enumeratum enums.

Since version 0.20.0-M10 it is possible to provide custom encoded value, e.g.:

case class Input(
    @default(E.Value, encoded=Some("Value"))
    e: E
    //...
)

// or

case class Input(
    @default(E.Value, encoded=Some(E.Value))
    e: E
    //...
)

[chessman]

@sijarsu Thanks for the fix!

I tested it out and noticed that it doesn't work when an enum is wrapped in Option:

  case class Input(
     e: Option[E]
  )

Neither @default(E.Value, Some(E.Value)) nor @default(Option(E.Value), Some(E.Value)) works in this case.

[chessman]

Oh, it is not related to enumeratum. Annotations for case classes wrapped in Option also don't work. Like:

    @encodedExample(A("a").asJson)
    @default(A("a"), Some("a"))
    a: Option[A]

created an issue: #1920