From 5c91288341f3dedbd86f19fad5057c9284b275ca Mon Sep 17 00:00:00 2001
From: Martin Pallmann <sayhello@martinpallmann.de>
Date: Wed, 9 Feb 2022 11:09:54 +0100
Subject: [PATCH] #1808: add external Refs (#1831)

* #1808: add external Refs

* #1808: improvements

* #1808: use single quotes
---
 .../schema/NameToSchemaReference.scala        |  8 ++++-
 .../src/test/resources/expected_external.yml  | 17 +++++++++++
 .../tapir/docs/openapi/VerifyYamlTest.scala   | 29 +++++++++++++++++++
 3 files changed, 53 insertions(+), 1 deletion(-)
 create mode 100644 docs/openapi-docs/src/test/resources/expected_external.yml

diff --git a/docs/apispec-docs/src/main/scala/sttp/tapir/docs/apispec/schema/NameToSchemaReference.scala b/docs/apispec-docs/src/main/scala/sttp/tapir/docs/apispec/schema/NameToSchemaReference.scala
index 676520729a..bbaa418ee5 100644
--- a/docs/apispec-docs/src/main/scala/sttp/tapir/docs/apispec/schema/NameToSchemaReference.scala
+++ b/docs/apispec-docs/src/main/scala/sttp/tapir/docs/apispec/schema/NameToSchemaReference.scala
@@ -5,6 +5,12 @@ import sttp.tapir.{Schema => TSchema}
 
 private[schema] class NameToSchemaReference(nameToKey: Map[TSchema.SName, ObjectKey]) {
   def map(name: TSchema.SName): Reference = {
-    Reference.to("#/components/schemas/", nameToKey(name))
+    nameToKey.get(name) match {
+      case Some(key) =>
+        Reference.to("#/components/schemas/", key)
+      case None =>
+        // no reference to internal model found. assuming external reference
+        Reference(name.fullName)
+    }
   }
 }
diff --git a/docs/openapi-docs/src/test/resources/expected_external.yml b/docs/openapi-docs/src/test/resources/expected_external.yml
new file mode 100644
index 0000000000..2f56cbe7c3
--- /dev/null
+++ b/docs/openapi-docs/src/test/resources/expected_external.yml
@@ -0,0 +1,17 @@
+openapi: '3.0.3'
+info:
+  title: 'Fruits'
+  version: '1.0'
+paths:
+  /:
+    get:
+      operationId: 'getRoot'
+      responses:
+        '200':
+          description: ''
+        default:
+          description: ''
+          content:
+            application/json:
+              schema:
+                $ref: 'https://example.com/models/model.yaml#/Problem'
diff --git a/docs/openapi-docs/src/test/scala/sttp/tapir/docs/openapi/VerifyYamlTest.scala b/docs/openapi-docs/src/test/scala/sttp/tapir/docs/openapi/VerifyYamlTest.scala
index b80728a73f..dd96dc8b5c 100644
--- a/docs/openapi-docs/src/test/scala/sttp/tapir/docs/openapi/VerifyYamlTest.scala
+++ b/docs/openapi-docs/src/test/scala/sttp/tapir/docs/openapi/VerifyYamlTest.scala
@@ -2,6 +2,7 @@ package sttp.tapir.docs.openapi
 
 import io.circe.Json
 import io.circe.generic.auto._
+import io.circe.yaml.Printer.StringStyle
 import io.circe.yaml.Printer.StringStyle.{DoubleQuoted, Literal}
 import org.scalatest.funsuite.AnyFunSuite
 import org.scalatest.matchers.should.Matchers
@@ -10,6 +11,7 @@ import sttp.model.{Method, StatusCode}
 import sttp.tapir.Schema.SName
 import sttp.tapir.Schema.annotations.description
 import sttp.tapir.docs.apispec.DocsExtension
+import sttp.tapir.docs.openapi.VerifyYamlTest.Problem
 import sttp.tapir.docs.openapi.dtos.VerifyYamlTestData._
 import sttp.tapir.docs.openapi.dtos.VerifyYamlTestData2._
 import sttp.tapir.docs.openapi.dtos.Book
@@ -44,6 +46,20 @@ class VerifyYamlTest extends AnyFunSuite with Matchers {
     actualYamlNoIndent shouldBe expectedYaml
   }
 
+  test("should match the expected yaml when there are external references") {
+    val external_reference: PublicEndpoint[Unit, Problem, Unit, Any] =
+      endpoint.errorOut(jsonBody[Problem])
+
+    val expectedYaml = load("expected_external.yml")
+
+    val actualYaml =
+      OpenAPIDocsInterpreter().toOpenAPI(List(external_reference), Info("Fruits", "1.0")).toYaml(StringStyle.SingleQuoted)
+
+    val actualYamlNoIndent = noIndentation(actualYaml)
+
+    actualYamlNoIndent shouldBe expectedYaml
+  }
+
   val endpoint_wit_recursive_structure: Endpoint[Unit, Unit, Unit, F1, Any] = endpoint.out(jsonBody[F1])
 
   test("should match the expected yaml when schema is recursive") {
@@ -602,3 +618,16 @@ class VerifyYamlTest extends AnyFunSuite with Matchers {
     noIndentation(actualYaml) shouldBe expectedYaml
   }
 }
+
+object VerifyYamlTest {
+  case class Problem()
+
+  object Problem {
+    implicit val schema: Schema[Problem] =
+      Schema[Problem](
+        SchemaType.SRef(
+          Schema.SName("https://example.com/models/model.yaml#/Problem")
+        )
+      )
+  }
+}