From 52734f3fca237dc33bb0db0c4445e7f6d58ed945 Mon Sep 17 00:00:00 2001
From: Arieh Schneier <15041913+AriehSchneier@users.noreply.github.com>
Date: Thu, 2 May 2024 16:14:06 +1000
Subject: [PATCH] Satisfy error and Validator interfaces for oneOf return types
 (#434)

---
 codegen/arrai/auto/svc_types.arrai            | 13 ++++++++++++
 .../cmd/gateway/main_test.go                  | 21 +++++++++++++++++--
 .../specs/oneOf_backend.yaml                  |  8 +++++++
 .../specs/oneOf_gateway.yaml                  |  8 +++++++
 4 files changed, 48 insertions(+), 2 deletions(-)

diff --git a/codegen/arrai/auto/svc_types.arrai b/codegen/arrai/auto/svc_types.arrai
index 82eca7c6..18ea4e2d 100644
--- a/codegen/arrai/auto/svc_types.arrai
+++ b/codegen/arrai/auto/svc_types.arrai
@@ -244,6 +244,19 @@ let fieldJsonTag = \type \key
                     `::\i}
             }
 
+            ${cond {typename <: go.errorReturnTypes(app): $`
+                // Error fulfills the error interface.
+                func (s ${typename}) Error() string {
+                    type plain ${typename}
+                    return fmt.Sprintf("%+v", plain(s))
+                }
+            `}}
+
+            // *${typename} validator
+            func (s *${typename}) Validate() error {
+                return validator.Validate(s)
+            }
+
             // Marshal data from the first non-nil pointer in the struct to JSON
             func (dst ${typename}) MarshalJSON() ([]byte, error) {
                 ${unionTypes >> $`
diff --git a/codegen/arrai/auto/tests/rest_miscellaneous/cmd/gateway/main_test.go b/codegen/arrai/auto/tests/rest_miscellaneous/cmd/gateway/main_test.go
index 8b735e6c..2c4d4260 100644
--- a/codegen/arrai/auto/tests/rest_miscellaneous/cmd/gateway/main_test.go
+++ b/codegen/arrai/auto/tests/rest_miscellaneous/cmd/gateway/main_test.go
@@ -11,6 +11,7 @@ import (
 	"testing"
 	"time"
 
+	"github.com/anz-bank/sysl-go/validator"
 	"rest_miscellaneous/internal/gen/pkg/servers/gateway"
 	"rest_miscellaneous/internal/gen/pkg/servers/gateway/array_response_backend"
 	"rest_miscellaneous/internal/gen/pkg/servers/gateway/encoder_backend"
@@ -18,10 +19,11 @@ import (
 	"rest_miscellaneous/internal/gen/pkg/servers/gateway/oneof_backend"
 	"rest_miscellaneous/internal/gen/pkg/servers/gateway/types"
 
-	"github.com/anz-bank/sysl-go/common"
-	"github.com/anz-bank/sysl-go/core"
 	"github.com/sethvargo/go-retry"
 	"github.com/stretchr/testify/require"
+
+	"github.com/anz-bank/sysl-go/common"
+	"github.com/anz-bank/sysl-go/core"
 )
 
 const applicationConfig = `---
@@ -307,6 +309,21 @@ func TestMiscellaneous_OneOfRaw(t *testing.T) {
 		Send()
 }
 
+func TestMiscellaneous_OneOfErrorReturn(t *testing.T) {
+	t.Parallel()
+
+	// Just want to confirm that it generates types that satisfy the 'error' and 'Validator' interfaces
+	var e error
+	e = gateway.Post_rotateOneOf_400_resp_type_body{}
+	e = oneof_backend.Post_rotateOneOf_400_resp_type_body{}
+	_ = e
+
+	var v validator.Validator
+	v = &gateway.Post_rotateOneOf_400_resp_type_body{}
+	v = &oneof_backend.Post_rotateOneOf_400_resp_type_body{}
+	_ = v
+}
+
 func TestMiscellaneous_MultiCode(t *testing.T) {
 	t.Parallel()
 	gatewayTester := gateway.NewTestServer(t, context.Background(), createService, "")
diff --git a/codegen/arrai/auto/tests/rest_miscellaneous/specs/oneOf_backend.yaml b/codegen/arrai/auto/tests/rest_miscellaneous/specs/oneOf_backend.yaml
index f0678d64..4902adb9 100644
--- a/codegen/arrai/auto/tests/rest_miscellaneous/specs/oneOf_backend.yaml
+++ b/codegen/arrai/auto/tests/rest_miscellaneous/specs/oneOf_backend.yaml
@@ -21,6 +21,14 @@ paths:
             application/json; charset = utf-8:
               schema:
                 $ref: "#/components/schemas/OneOfResponse"
+        '400':
+          description: error
+          content:
+            application/json:
+              schema:
+                oneOf:
+                  - $ref: "#/components/schemas/One"
+                  - $ref: "#/components/schemas/Two"
 
 components:
   schemas:
diff --git a/codegen/arrai/auto/tests/rest_miscellaneous/specs/oneOf_gateway.yaml b/codegen/arrai/auto/tests/rest_miscellaneous/specs/oneOf_gateway.yaml
index 05c30f90..34d94f5e 100644
--- a/codegen/arrai/auto/tests/rest_miscellaneous/specs/oneOf_gateway.yaml
+++ b/codegen/arrai/auto/tests/rest_miscellaneous/specs/oneOf_gateway.yaml
@@ -28,6 +28,14 @@ paths:
               example:
                 values:
                   - one: true
+        '400':
+          description: error
+          content:
+            application/json:
+              schema:
+                oneOf:
+                  - $ref: "#/components/schemas/One"
+                  - $ref: "#/components/schemas/Two"
 
 components:
   schemas: