feat(infra/clock): injectable Clock with Real and Fake implementations

internal/infra/clock/clock_test.go

@@ -0,0 +1,54 @@
+package clock
+
+import (
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestRealClock_Now(t *testing.T) {
+	c := Real()
+	now := c.Now()
+	assert.WithinDuration(t, time.Now(), now, time.Second)
+}
+
+func TestFakeClock_NowReturnsSetTime(t *testing.T) {
+	t0 := time.Date(2026, 5, 5, 10, 0, 0, 0, time.UTC)
+	c := NewFake(t0)
+	assert.Equal(t, t0, c.Now())
+}
+
+func TestFakeClock_Advance(t *testing.T) {
+	t0 := time.Date(2026, 5, 5, 10, 0, 0, 0, time.UTC)
+	c := NewFake(t0)
+	c.Advance(2 * time.Hour)
+	assert.Equal(t, t0.Add(2*time.Hour), c.Now())
+}
+
+func TestFakeClock_AdvanceConcurrent(t *testing.T) {
+	c := NewFake(time.Now())
+	done := make(chan struct{})
+	go func() {
+		for i := 0; i < 1000; i++ {
+			c.Advance(time.Microsecond)
+		}
+		close(done)
+	}()
+	for i := 0; i < 1000; i++ {
+		_ = c.Now()
+	}
+	<-done
+}
+
+func TestFakeClock_Set(t *testing.T) {
+	c := NewFake(time.Date(2026, 5, 5, 10, 0, 0, 0, time.UTC))
+	t1 := time.Date(2027, 1, 1, 0, 0, 0, 0, time.UTC)
+	c.Set(t1)
+	assert.Equal(t, t1, c.Now())
+}
+
+var _ Clock = (*realClock)(nil)
+var _ Clock = (*FakeClock)(nil)
+var _ = require.New // keep import live; helper used by other packages