feat(updater): FIFO queue with single worker and per-job results

internal/updater/worker_test.go

@@ -0,0 +1,38 @@
+package updater_test
+
+import (
+	"context"
+	"sync/atomic"
+	"testing"
+	"time"
+
+	"github.com/shcizo/package-updater/internal/discovery"
+	"github.com/shcizo/package-updater/internal/updater"
+	"github.com/stretchr/testify/require"
+)
+
+type counterExec struct{ n atomic.Int32 }
+
+func (c *counterExec) Execute(_ context.Context, _ discovery.Job) error {
+	c.n.Add(1)
+	time.Sleep(10 * time.Millisecond)
+	return nil
+}
+
+func TestWorker_RunsExactlyOneAtATime(t *testing.T) {
+	exec := &counterExec{}
+	q := updater.NewQueue(exec)
+	q.Start(context.Background())
+	defer q.Stop()
+
+	jobs := make([]discovery.Job, 10)
+	for i := range jobs {
+		jobs[i] = discovery.Job{Project: "p", Service: "svc"}
+	}
+	start := time.Now()
+	q.Submit(context.Background(), jobs)
+	elapsed := time.Since(start)
+
+	require.GreaterOrEqual(t, elapsed, 90*time.Millisecond)
+	require.Equal(t, int32(10), exec.n.Load())
+}