fix(internal/serviceconfig): set transport at API level (#3958)

Set transport of `google/cloud/aiplatform/v1` to grpc.

The value is non-default and is different than another api
(`google/cloud/aiplatform/v1beta1`) in the library. Therefore, set it in
API level, rather than library level.

For #3618

Author: JoeWang1127

doc/api-allowlist-schema.md

@@ -4,7 +4,7 @@ This document describes the schema for the API Allowlist.
 
 ## API Configuration
 
-[Link to code](../internal/serviceconfig/api.go#L48)
+[Link to code](../internal/serviceconfig/api.go#L49)
 | Field | Type | Description |
 | :--- | :--- | :--- |
 | `Path` | string | Path is the proto directory path in github.com/googleapis/googleapis. If ServiceConfig is empty, the service config is assumed to live at this path. |

internal/librarian/golang/generate.go

@@ -181,11 +181,7 @@ func buildGAPICOpts(apiPath string, library *config.Library, goAPI *config.GoAPI
 	// TODO(https://github.com/googleapis/librarian/issues/3775): assuming
 	// transport is library-wide for now, until we have figured out the config
 	// for transports.
-	transport := library.Transport
-	if transport == "" {
-		transport = "grpc+rest"
-	}
-	opts = append(opts, "transport="+transport)
+	opts = append(opts, "transport="+getTransport(sc))
 	if library.ReleaseLevel != "" {
 		opts = append(opts, "release-level="+library.ReleaseLevel)
 	}
@@ -373,3 +369,13 @@ func updateSnippetMetadata(library *config.Library, output string) error {
 		return nil
 	})
 }
+
+// getTransport get transport from serviceconfig.API for language Go.
+//
+// The default value is serviceconfig.GRPCRest.
+func getTransport(sc *serviceconfig.API) string {
+	if sc != nil {
+		return sc.Transport("go")
+	}
+	return string(serviceconfig.GRPCRest)
+}

internal/librarian/golang/generate_test.go

@@ -351,3 +351,47 @@ func TestBuildGAPICImportPath(t *testing.T) {
 		})
 	}
 }
+
+func TestGetTransport(t *testing.T) {
+	for _, test := range []struct {
+		name string
+		sc   *serviceconfig.API
+		want string
+	}{
+		{
+			name: "nil serviceconfig",
+			sc:   nil,
+			want: "grpc+rest",
+		},
+		{
+			name: "empty serviceconfig",
+			sc:   &serviceconfig.API{},
+			want: "grpc+rest",
+		},
+		{
+			name: "go specific transport",
+			sc: &serviceconfig.API{
+				Transports: map[string]serviceconfig.Transport{
+					"go": serviceconfig.GRPC,
+				},
+			},
+			want: "grpc",
+		},
+		{
+			name: "other language transport",
+			sc: &serviceconfig.API{
+				Transports: map[string]serviceconfig.Transport{
+					"python": serviceconfig.GRPC,
+				},
+			},
+			want: "grpc+rest",
+		},
+	} {
+		t.Run(test.name, func(t *testing.T) {
+			got := getTransport(test.sc)
+			if diff := cmp.Diff(test.want, got); diff != "" {
+				t.Errorf("mismatch (-want +got):\n%s", diff)
+			}
+		})
+	}
+}

internal/serviceconfig/api.go

@@ -18,6 +18,7 @@ package serviceconfig
 
 const (
 	langDart   = "dart"
+	langGo     = "go"
 	langPython = "python"
 	langRust   = "rust"
 
@@ -81,6 +82,17 @@ type API struct {
 	Transports map[string]Transport
 }
 
+// Transport gets transport for a given language.
+//
+// The default value is GRPCRest, if undefined for a language.
+func (api *API) Transport(language string) string {
+	if trans, ok := api.Transports[language]; ok {
+		return string(trans)
+	}
+
+	return string(GRPCRest)
+}
+
 // APIs defines all API paths and their language availability.
 var APIs = []API{
 	{Path: "google/ads/admanager/v1", Languages: []string{langPython}},
@@ -121,7 +133,7 @@ var APIs = []API{
 	{Path: "google/chat/v1", Languages: []string{langPython}},
 	{Path: "google/cloud/accessapproval/v1"},
 	{Path: "google/cloud/advisorynotifications/v1"},
-	{Path: "google/cloud/aiplatform/v1"},
+	{Path: "google/cloud/aiplatform/v1", Transports: map[string]Transport{langGo: GRPC}},
 	{Path: "google/cloud/aiplatform/v1/schema/predict/instance", ServiceConfig: serviceConfigAIPlatformSchema},
 	{Path: "google/cloud/aiplatform/v1/schema/predict/params", ServiceConfig: serviceConfigAIPlatformSchema},
 	{Path: "google/cloud/aiplatform/v1/schema/predict/prediction", ServiceConfig: serviceConfigAIPlatformSchema},

internal/serviceconfig/api_test.go

@@ -16,6 +16,8 @@ package serviceconfig
 
 import (
 	"testing"
+
+	"github.com/google/go-cmp/cmp"
 )
 
 func TestAPIsNoDuplicates(t *testing.T) {
@@ -37,3 +39,46 @@ func TestAPIsAlphabeticalOrder(t *testing.T) {
 		}
 	}
 }
+
+func TestGetTransport(t *testing.T) {
+	for _, test := range []struct {
+		name string
+		sc   *API
+		lang string
+		want string
+	}{
+		{
+			name: "empty serviceconfig",
+			sc:   &API{},
+			lang: "go",
+			want: "grpc+rest",
+		},
+		{
+			name: "go specific transport",
+			sc: &API{
+				Transports: map[string]Transport{
+					"go": GRPC,
+				},
+			},
+			lang: "go",
+			want: "grpc",
+		},
+		{
+			name: "other language transport",
+			sc: &API{
+				Transports: map[string]Transport{
+					"go": GRPC,
+				},
+			},
+			lang: "python",
+			want: "grpc+rest",
+		},
+	} {
+		t.Run(test.name, func(t *testing.T) {
+			got := test.sc.Transport(test.lang)
+			if diff := cmp.Diff(test.want, got); diff != "" {
+				t.Errorf("mismatch (-want +got):\n%s", diff)
+			}
+		})
+	}
+}