feat(gl): scaffold general ledger grpc service

application/health/service.go

@@ -0,0 +1,29 @@
+// Package health provides the service readiness use case.
+package health
+
+import "context"
+
+type Database interface {
+	Ping(context.Context) error
+}
+
+type Status struct {
+	Serving       bool
+	DatabaseReady bool
+}
+
+type Service struct {
+	database Database
+}
+
+func NewService(database Database) *Service {
+	return &Service{database: database}
+}
+
+func (s *Service) Check(ctx context.Context) Status {
+	status := Status{Serving: true}
+	if s.database != nil {
+		status.DatabaseReady = s.database.Ping(ctx) == nil
+	}
+	return status
+}

application/health/service_test.go

@@ -0,0 +1,30 @@
+package health
+
+import (
+	"context"
+	"errors"
+	"testing"
+)
+
+type databaseStub struct{ err error }
+
+func (s databaseStub) Ping(context.Context) error { return s.err }
+
+func TestCheckReportsDatabaseReadiness(t *testing.T) {
+	for _, tc := range []struct {
+		name  string
+		db    Database
+		ready bool
+	}{
+		{name: "not connected", db: nil, ready: false},
+		{name: "ready", db: databaseStub{}, ready: true},
+		{name: "unavailable", db: databaseStub{err: errors.New("down")}, ready: false},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			got := NewService(tc.db).Check(context.Background())
+			if !got.Serving || got.DatabaseReady != tc.ready {
+				t.Fatalf("unexpected status: %+v", got)
+			}
+		})
+	}
+}