feat: add option.DefaultResponse (#425)

* feat: add OptionAddDefaultResponse

* Adds OptionDefaultResponse to add a default response to a route

openapi_operations_test.go

@@ -4,6 +4,7 @@ import (
 	"net/http"
 	"testing"
 
+	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
 
@@ -189,6 +190,14 @@ func TestWithGlobalResponseType(t *testing.T) {
 				routeCustom.Operation.Responses.Value("202").Value.Content.Get("application/x-yaml").Schema.Ref,
 			)
 		})
+
+		t.Run("global 'default' response", func(t *testing.T) {
+			route := Get(s, "/test", testController,
+				OptionDefaultResponse("Default response", Response{Type: HTTPError{}}),
+			)
+			assert.Equal(t, "Default response", *route.Operation.Responses.Value("default").Value.Description)
+			assert.Equal(t, "#/components/schemas/HTTPError", route.Operation.Responses.Value("default").Value.Content.Get("application/json").Schema.Ref)
+		})
 	})
 
 	t.Run("should be fatal", func(t *testing.T) {

option.go

@@ -361,6 +361,22 @@ func OptionAddResponse(code int, description string, response Response) func(*Ba
 	}
 }
 
+// OptionDefaultResponse adds a default response to a route
+// Required: Response.Type must be set
+// Optional: Response.ContentTypes will default to `application/json` and `application/xml` if not set
+func OptionDefaultResponse(description string, response Response) func(*BaseRoute) {
+	return func(r *BaseRoute) {
+		if r.Operation.Responses == nil {
+			r.Operation.Responses = openapi3.NewResponses()
+		}
+		r.Operation.Responses.Set(
+			"default", &openapi3.ResponseRef{
+				Value: r.OpenAPI.buildOpenapi3Response(description, response),
+			},
+		)
+	}
+}
+
 // OptionRequestContentType sets the accepted content types for the route.
 // By default, the accepted content types is */*.
 // This will override any options set at the server level.