feat: add timez.Now() func (#81)

time/time.go

@@ -0,0 +1,48 @@
+package timez
+
+import (
+	"context"
+	"sync"
+	"time"
+)
+
+type ctxKeyNow struct{}
+
+func Now(ctx context.Context) time.Time {
+	nowFuncRWMu.RLock()
+	defer nowFuncRWMu.RUnlock()
+	return nowFunc(ctx)
+}
+
+//nolint:gochecknoglobals
+var (
+	nowFunc     = DefaultNowFunc
+	nowFuncRWMu sync.RWMutex
+)
+
+type NowFunc = func(ctx context.Context) time.Time
+
+func DefaultNowFunc(ctx context.Context) time.Time {
+	if now, ok := FromContext(ctx); ok {
+		return now
+	}
+
+	return time.Now()
+}
+
+func SetNowFunc(now NowFunc) (backup NowFunc) {
+	nowFuncRWMu.Lock()
+	defer nowFuncRWMu.Unlock()
+	backup = nowFunc
+	nowFunc = now
+	return backup
+}
+
+func WithContext(ctx context.Context, now time.Time) context.Context {
+	return context.WithValue(ctx, ctxKeyNow{}, now)
+}
+
+func FromContext(ctx context.Context) (time.Time, bool) {
+	now, ok := ctx.Value(ctxKeyNow{}).(time.Time)
+	return now, ok
+}

time/time_test.go

@@ -0,0 +1,37 @@
+package timez_test
+
+import (
+	"context"
+	"testing"
+	"time"
+
+	timez "github.com/kunitsucom/util.go/time"
+)
+
+func TestNow(t *testing.T) {
+	t.Parallel()
+	t.Run("success,", func(t *testing.T) {
+		t.Parallel()
+
+		ctx := context.Background()
+		constant := time.Date(2023, 8, 24, 21, 32, 0, 0, time.UTC)
+		ctx = timez.WithContext(ctx, constant)
+
+		actual := timez.Now(ctx)
+		if constant != actual {
+			t.Errorf("❌: constant(%v) != actual(%v)", constant, actual)
+		}
+
+		backup := timez.SetNowFunc(func(_ context.Context) time.Time { return time.Now() })
+		current := timez.Now(context.Background())
+		if current.After(constant) {
+			t.Errorf("❌: current(%v) after constant(%v)", current, constant)
+		}
+
+		timez.SetNowFunc(backup)
+		current2 := timez.Now(context.Background())
+		if !current2.After(current) {
+			t.Errorf("❌: current2(%v) after current(%v)", current2, current)
+		}
+	})
+}