Abstract a request counter's cycle logic from watch()

legacy/reqcounter/reqcounter.go

@@ -64,16 +64,22 @@ func (rc *RequestCounter) reset() {
 	rc.Since = Clock.Now()
 }
 
-// watch continuously logs the request counter at the specified intervals.
+// watch indefinitely performs repeated sleep/log cycles.
 func (rc *RequestCounter) watch() {
+	// TODO: @tylerferrara create a way to cleanly terminate this goroutine.
 	go func() {
 		for {
-			Clock.Sleep(rc.Interval)
-			rc.Flush()
+			rc.Cycle()
 		}
 	}()
 }
 
+// Cycle sleeps for the request counter's interval and flushes itself.
+func (rc *RequestCounter) Cycle() {
+	Clock.Sleep(rc.Interval)
+	rc.Flush()
+}
+
 // RequestCounters holds multiple request counters.
 type RequestCounters []*RequestCounter
 

legacy/reqcounter/reqcounter_test.go

@@ -17,12 +17,14 @@ limitations under the License.
 package reqcounter_test
 
 import (
+	"fmt"
 	"sync"
 	"testing"
 	"time"
 
 	"github.com/stretchr/testify/require"
 	rc "sigs.k8s.io/k8s-container-image-promoter/legacy/reqcounter"
+	tw "sigs.k8s.io/k8s-container-image-promoter/legacy/timewrapper"
 )
 
 // defaultTime should be used as a timestamp for all request counters.
@@ -124,3 +126,35 @@ func TestRequestCounterIncrement(t *testing.T) {
 	// Ensure the request counter was incremented.
 	require.EqualValues(t, &expected, &requestCounter, "The request counter failed to increment its request field.")
 }
+
+func TestCycle(t *testing.T) {
+	// Create a simple request counter expected to log every 10 minutes.
+	requestCounter := NewRequestCounter(82)
+	requestCounter.Interval = time.Minute * 10
+	// Collect logging statements.
+	logs := []string{}
+	// Mock logrus.Debug calls.
+	rc.Debug = func(args ...interface{}) {
+		logs = append(logs, fmt.Sprint(args[0]))
+	}
+	// Mock time.
+	fakeTime := tw.FakeTime{
+		Time: defaultTime,
+	}
+	rc.Clock = &fakeTime
+	// Determine the expected logs.
+	expected := []string{
+		"From 2006-01-02 15:04:05 to 2006-01-02 15:14:05 [10 min] there have been 82 requests to GCR.",
+		"From 2006-01-02 15:14:05 to 2006-01-02 15:24:05 [10 min] there have been 0 requests to GCR.",
+		"From 2006-01-02 15:24:05 to 2006-01-02 15:34:05 [10 min] there have been 0 requests to GCR.",
+		"From 2006-01-02 15:34:05 to 2006-01-02 15:44:05 [10 min] there have been 0 requests to GCR.",
+		"From 2006-01-02 15:44:05 to 2006-01-02 15:54:05 [10 min] there have been 0 requests to GCR.",
+	}
+	// Repeatedly run sleep/log cycles.
+	numCycles := len(expected)
+	for i := 0; i < numCycles; i++ {
+		requestCounter.Cycle()
+	}
+	// Ensure the correct logs were produced.
+	require.EqualValues(t, expected, logs, "The request counter produced malformed logs.")
+}

legacy/timewrapper/timewrapper.go

@@ -41,7 +41,9 @@ type FakeTime struct {
 }
 
 // Now returns the global fake time.
-func (ft FakeTime) Now() time.Time { return ft.Time }
+func (ft *FakeTime) Now() time.Time { return ft.Time }
 
-// Sleep does not block the current goroutine.
-func (ft FakeTime) Sleep(d time.Duration) {}
+// Sleep adds the given duration to the global fake time.
+func (ft *FakeTime) Sleep(d time.Duration) {
+	ft.Time = ft.Time.Add(d)
+}