metrics: use testTime instead of now, and make testTime increment.

Merge with the metrics commit on the next rebase.

Author: bwesterb

src/crypto/tls/handshake_test.go

@@ -20,6 +20,7 @@ import (
 	"strconv"
 	"strings"
 	"sync"
+	"sync/atomic"
 	"testing"
 	"time"
 )
@@ -429,10 +430,17 @@ func fromHex(s string) []byte {
 	return b
 }
 
-// testTime is 2016-10-20T17:32:09.000Z, which is within the validity period of
-// [testRSACertificate], [testRSACertificateIssuer], [testRSA2048Certificate],
-// [testRSA2048CertificateIssuer], and [testECDSACertificate].
-var testTime = func() time.Time { return time.Unix(1476984729, 0) }
+// Returns currentTestTime and then increments by a second.
+var testTime = func() time.Time { return time.Unix(currentTestTime.Add(1), 0) }
+
+// currentTestTime is initially 2016-10-20T17:32:09.000Z, which is well within
+// the validity period of [testRSACertificate], [testRSACertificateIssuer],
+// [testRSA2048Certificate], [testRSA2048CertificateIssuer], and [testECDSACertificate].
+var currentTestTime atomic.Int64
+
+func init() {
+	currentTestTime.Store(1476984729)
+}
 
 var testRSACertificate = fromHex("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")
 

src/crypto/tls/metrics_test.go

@@ -10,7 +10,6 @@ import (
 	"io"
 	"io/ioutil"
 	"testing"
-	"time"
 )
 
 type testTimingInfo struct {
@@ -106,7 +105,7 @@ func TestTLS13HandshakeTiming(t *testing.T) {
 	const serverName = "example.golang"
 
 	baseConfig := &Config{
-		Time:         time.Now,
+		Time:         testTime,
 		Rand:         zeroSource{},
 		Certificates: make([]Certificate, 1),
 		MaxVersion:   VersionTLS13,