fix(go): support form-urlencoded request body encoding (#11426)

* fix(go): support form-urlencoded request body encoding

OAuth token requests and other endpoints with `application/x-www-form-urlencoded`
content type were failing because the Go SDK always serialized request bodies as
JSON, regardless of the Content-Type header.

This fix modifies the internal caller to:
- Detect form-urlencoded content type from endpoint headers
- Use `url.Values.Encode()` for form-urlencoded requests instead of JSON marshaling
- Properly handle struct fields using json tags for field names

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <[email protected]>

* feat(go): add wire tests for OAuth client credentials fixture

- Add OAuthWireTestGenerator to generate OAuth-specific wire tests
- Enable wire tests for oauth-client-credentials fixture in seed.yml
- Add content-type: application/x-www-form-urlencoded to OAuth token endpoints
- Tests validate form URL encoded body encoding and custom header propagation

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <[email protected]>

* fix(go): make OAuth wire tests dynamic to support different SDK structures

The OAuth wire test generator now dynamically extracts service structure
from the IR instead of hardcoding assumptions. This allows the tests to
work with different OAuth configurations:

- Service accessor path (e.g., OAuth2 vs Auth)
- Method name (e.g., GetToken vs GetTokenWithClientCredentials)
- Field names (e.g., ClientID vs ClientId)
- Field types (optional pointer vs required string)
- Test file location based on actual service package

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <[email protected]>

* Update version

* chore: update oauth-client-credentials test definition

Co-Authored-By: [email protected] <[email protected]>

* chore: remove oauth-client-credentials from seed-groups.json files

Co-Authored-By: [email protected] <[email protected]>

* refactor(go): improve OAuthWireTestGenerator to follow canonical patterns

- Use context.getClientFileLocation() instead of custom getPackageDir() logic
- Use context.getFieldName() for field names instead of custom goExportedFieldName
- Implement dynamic request type derivation matching ClientGenerator pattern
- Add helper methods for request property field names and optionality checks

Co-Authored-By: [email protected] <[email protected]>

* test(go): add unit tests for form URL encoding in caller

- Add TestNewFormURLEncodedBody for map-based form encoding
- Add TestNewFormURLEncodedRequestBody for struct-based form encoding
- Add TestNewRequestBodyFormURLEncoded for content-type selection logic
- Include tests for special characters, omitempty handling, and pointer fields

Co-Authored-By: [email protected] <[email protected]>

* Update new test and confirm tests pass in fixture

* Update go sdk output

* fix(go): use unique docker-compose project names to prevent parallel test conflicts

Co-Authored-By: [email protected] <[email protected]>

---------

Co-authored-by: jsklan <[email protected]>
Co-authored-by: Claude Opus 4.5 <[email protected]>
Co-authored-by: Devin AI <158243242+devin-ai-integration[bot]@users.noreply.github.com>

Author: 4 people

.github/workflow-resource-files/seed-groups/go-sdk-seed-groups.json

@@ -2,11 +2,10 @@
   "totalTestTimeSeconds": 8426,
   "groups": [
     {
-      "fixtures": [
-        "version",
-        "simple-api",
-        "oauth-client-credentials",
-        "imdb:deep-package-path",
+            "fixtures": [
+              "version",
+              "simple-api",
+              "imdb:deep-package-path",
         "imdb:package-path",
         "inferred-auth-explicit",
         "package-yml:no-custom-config",

.github/workflow-resource-files/seed-groups/php-sdk-seed-groups.json

@@ -2,16 +2,15 @@
   "totalTestTimeSeconds": 8014,
   "groups": [
     {
-      "fixtures": [
-        "query-parameters-openapi-as-objects",
-        "oauth-client-credentials-nested-root",
-        "pagination:no-custom-config",
-        "property-access",
-        "mixed-case",
-        "inferred-auth-implicit-no-expiry",
-        "simple-fhir",
-        "oauth-client-credentials",
-        "websocket-bearer-auth",
+            "fixtures": [
+              "query-parameters-openapi-as-objects",
+              "oauth-client-credentials-nested-root",
+              "pagination:no-custom-config",
+              "property-access",
+              "mixed-case",
+              "inferred-auth-implicit-no-expiry",
+              "simple-fhir",
+              "websocket-bearer-auth",
         "cross-package-type-names",
         "examples:readme-config"
       ],

generators/go-v2/base/src/asIs/internal/caller.go_

@@ -17,8 +17,9 @@ import (
 
 const (
 	// contentType specifies the JSON Content-Type header value.
-	contentType       = "application/json"
-	contentTypeHeader = "Content-Type"
+	contentType            = "application/json"
+	contentTypeHeader      = "Content-Type"
+	contentTypeFormURLEncoded = "application/x-www-form-urlencoded"
 )
 
 // Caller calls APIs and deserializes their response, if any.
@@ -180,7 +181,14 @@ func newRequest(
 	request interface{},
 	bodyProperties map[string]interface{},
 ) (*http.Request, error) {
-	requestBody, err := newRequestBody(request, bodyProperties)
+	// Determine the content type from headers, defaulting to JSON.
+	reqContentType := contentType
+	if endpointHeaders != nil {
+		if ct := endpointHeaders.Get(contentTypeHeader); ct != "" {
+			reqContentType = ct
+		}
+	}
+	requestBody, err := newRequestBody(request, bodyProperties, reqContentType)
 	if err != nil {
 		return nil, err
 	}
@@ -189,19 +197,22 @@ func newRequest(
 		return nil, err
 	}
 	req = req.WithContext(ctx)
-	req.Header.Set(contentTypeHeader, contentType)
+	req.Header.Set(contentTypeHeader, reqContentType)
 	for name, values := range endpointHeaders {
 		req.Header[name] = values
 	}
 	return req, nil
 }
 
 // newRequestBody returns a new io.Reader that represents the HTTP request body.
-func newRequestBody(request interface{}, bodyProperties map[string]interface{}) (io.Reader, error) {
+func newRequestBody(request interface{}, bodyProperties map[string]interface{}, reqContentType string) (io.Reader, error) {
 	if isNil(request) {
 		if len(bodyProperties) == 0 {
 			return nil, nil
 		}
+		if reqContentType == contentTypeFormURLEncoded {
+			return newFormURLEncodedBody(bodyProperties), nil
+		}
 		requestBytes, err := json.Marshal(bodyProperties)
 		if err != nil {
 			return nil, err
@@ -211,13 +222,82 @@ func newRequestBody(request interface{}, bodyProperties map[string]interface{})
 	if body, ok := request.(io.Reader); ok {
 		return body, nil
 	}
+	// Handle form URL encoded content type.
+	if reqContentType == contentTypeFormURLEncoded {
+		return newFormURLEncodedRequestBody(request, bodyProperties)
+	}
 	requestBytes, err := MarshalJSONWithExtraProperties(request, bodyProperties)
 	if err != nil {
 		return nil, err
 	}
 	return bytes.NewReader(requestBytes), nil
 }
 
+// newFormURLEncodedBody returns a new io.Reader that represents a form URL encoded body
+// from the given body properties map.
+func newFormURLEncodedBody(bodyProperties map[string]interface{}) io.Reader {
+	values := url.Values{}
+	for key, val := range bodyProperties {
+		values.Set(key, fmt.Sprintf("%v", val))
+	}
+	return strings.NewReader(values.Encode())
+}
+
+// newFormURLEncodedRequestBody returns a new io.Reader that represents a form URL encoded body
+// from the given request struct and body properties.
+func newFormURLEncodedRequestBody(request interface{}, bodyProperties map[string]interface{}) (io.Reader, error) {
+	values := url.Values{}
+	// Use reflection to extract fields from the request struct.
+	val := reflect.ValueOf(request)
+	if val.Kind() == reflect.Ptr {
+		val = val.Elem()
+	}
+	if val.Kind() == reflect.Struct {
+		typ := val.Type()
+		for i := 0; i < val.NumField(); i++ {
+			field := typ.Field(i)
+			fieldVal := val.Field(i)
+			// Get the json tag to use as the key.
+			jsonTag := field.Tag.Get("json")
+			if jsonTag == "" || jsonTag == "-" {
+				continue
+			}
+			// Parse the json tag to get the field name (handles "name,omitempty").
+			tagName := strings.Split(jsonTag, ",")[0]
+			if tagName == "" {
+				continue
+			}
+			// Skip zero values for optional fields (those with omitempty).
+			if strings.Contains(jsonTag, "omitempty") && isZeroValue(fieldVal) {
+				continue
+			}
+			// Handle pointer types by dereferencing.
+			if fieldVal.Kind() == reflect.Ptr {
+				if fieldVal.IsNil() {
+					continue
+				}
+				fieldVal = fieldVal.Elem()
+			}
+			values.Set(tagName, fmt.Sprintf("%v", fieldVal.Interface()))
+		}
+	}
+	// Add any extra body properties.
+	for key, val := range bodyProperties {
+		values.Set(key, fmt.Sprintf("%v", val))
+	}
+	return strings.NewReader(values.Encode()), nil
+}
+
+// isZeroValue checks if the given reflect.Value is the zero value for its type.
+func isZeroValue(v reflect.Value) bool {
+	switch v.Kind() {
+	case reflect.Ptr, reflect.Interface, reflect.Slice, reflect.Map, reflect.Chan, reflect.Func:
+		return v.IsNil()
+	default:
+		return v.IsZero()
+	}
+}
+
 // decodeError decodes the error from the given HTTP response. Note that
 // it's the caller's responsibility to close the response body.
 func decodeError(response *http.Response, errorDecoder ErrorDecoder) error {