openapi2conv: convert references in nested additionalProperties schem…

…as (#1047)

* Convert references in nested additionalProperties schemas

When the schema specified in additionalProperties contains another
nested schema with additionalProperties, the references must be
converted at all of levels of the nested schemas.

* make toV3AdditionalProperties a non-exported function

openapi2conv/openapi2_conv.go

@@ -513,11 +513,7 @@ func ToV3SchemaRef(schema *openapi2.SchemaRef) *openapi3.SchemaRef {
 		MaxProps:             schema.Value.MaxProps,
 		AllOf:                make(openapi3.SchemaRefs, len(schema.Value.AllOf)),
 		Properties:           make(openapi3.Schemas),
-		AdditionalProperties: schema.Value.AdditionalProperties,
-	}
-
-	if schema.Value.AdditionalProperties.Schema != nil {
-		v3Schema.AdditionalProperties.Schema.Ref = ToV3Ref(schema.Value.AdditionalProperties.Schema.Ref)
+		AdditionalProperties: toV3AdditionalProperties(schema.Value.AdditionalProperties),
 	}
 
 	if schema.Value.Discriminator != "" {
@@ -551,6 +547,27 @@ func ToV3SchemaRef(schema *openapi2.SchemaRef) *openapi3.SchemaRef {
 	}
 }
 
+func toV3AdditionalProperties(from openapi3.AdditionalProperties) openapi3.AdditionalProperties {
+	return openapi3.AdditionalProperties{
+		Has:    from.Has,
+		Schema: convertRefsInV3SchemaRef(from.Schema),
+	}
+}
+
+func convertRefsInV3SchemaRef(from *openapi3.SchemaRef) *openapi3.SchemaRef {
+	if from == nil {
+		return nil
+	}
+	to := *from
+	to.Ref = ToV3Ref(to.Ref)
+	if to.Value != nil {
+		v := *from.Value
+		to.Value = &v
+		to.Value.AdditionalProperties = toV3AdditionalProperties(to.Value.AdditionalProperties)
+	}
+	return &to
+}
+
 var ref2To3 = map[string]string{
 	"#/definitions/": "#/components/schemas/",
 	"#/responses/":   "#/components/responses/",

openapi2conv/openapi2_conv_test.go

@@ -65,6 +65,134 @@ func TestConvOpenAPIV2ToV3(t *testing.T) {
 	require.JSONEq(t, exampleV3, string(data))
 }
 
+func TestConvOpenAPIV2ToV3WithAdditionalPropertiesSchemaRef(t *testing.T) {
+	v2 := []byte(`
+{
+    "basePath": "/v2",
+    "host": "test.example.com",
+    "info": {
+        "title": "MyAPI",
+        "version": "0.1"
+    },
+    "paths": {
+        "/foo": {
+            "get": {
+                "operationId": "getFoo",
+                "produces": [
+                    "application/json"
+                ],
+                "responses": {
+                    "200": {
+                        "description": "returns all information",
+                        "schema":{
+                            "type":"object",
+                            "additionalProperties":{
+                               "$ref":"#/definitions/Foo"
+                            }
+                        }
+                    }
+                },
+                "summary": "get foo"
+            }
+        }
+    },
+	"definitions": {
+	    "Foo": {
+		    "type": "object",
+			"properties": {
+			    "a": {
+				    "type": "string"
+				}
+			}
+		}
+	},
+    "schemes": [
+        "http"
+    ],
+    "swagger": "2.0"
+}
+`)
+
+	var doc2 openapi2.T
+	err := json.Unmarshal(v2, &doc2)
+	require.NoError(t, err)
+
+	doc3, err := ToV3(&doc2)
+	require.NoError(t, err)
+	err = doc3.Validate(context.Background())
+	require.NoError(t, err)
+
+	responseSchema := doc3.Paths.Value("/foo").Get.Responses.Value("200").Value.Content.Get("application/json").Schema.Value
+	require.Equal(t, &openapi3.Types{"object"}, responseSchema.Type)
+	require.Equal(t, "#/components/schemas/Foo", responseSchema.AdditionalProperties.Schema.Ref)
+}
+
+func TestConvOpenAPIV2ToV3WithNestedAdditionalPropertiesSchemaRef(t *testing.T) {
+	v2 := []byte(`
+{
+    "basePath": "/v2",
+    "host": "test.example.com",
+    "info": {
+        "title": "MyAPI",
+        "version": "0.1"
+    },
+    "paths": {
+        "/foo": {
+            "get": {
+                "operationId": "getFoo",
+                "produces": [
+                    "application/json"
+                ],
+                "responses": {
+                    "200": {
+                        "description": "returns all information",
+                        "schema":{
+                            "type":"object",
+                            "additionalProperties":{
+                               "type":"object",
+                               "additionalProperties":{
+                                   "$ref":"#/definitions/Foo"
+                               }
+                            }
+                        }
+                    }
+                },
+                "summary": "get foo"
+            }
+        }
+    },
+	"definitions": {
+	    "Foo": {
+		    "type": "object",
+			"properties": {
+			    "a": {
+				    "type": "string"
+				}
+			}
+		}
+	},
+    "schemes": [
+        "http"
+    ],
+    "swagger": "2.0"
+}
+`)
+
+	var doc2 openapi2.T
+	err := json.Unmarshal(v2, &doc2)
+	require.NoError(t, err)
+
+	doc3, err := ToV3(&doc2)
+	require.NoError(t, err)
+	err = doc3.Validate(context.Background())
+	require.NoError(t, err)
+
+	responseSchema := doc3.Paths.Value("/foo").Get.Responses.Value("200").Value.Content.Get("application/json").Schema.Value
+	require.Equal(t, &openapi3.Types{"object"}, responseSchema.Type)
+	require.Equal(t, &openapi3.Types{"object"}, responseSchema.AdditionalProperties.Schema.Value.Type)
+	require.Equal(t, "#/components/schemas/Foo", responseSchema.AdditionalProperties.Schema.Value.AdditionalProperties.Schema.Ref)
+}
+
 const exampleV2 = `
 {
 	"basePath": "/v2",