fix(fvt): ensure fully-replicated at test start (#2531)

Potential workaround for issues like #2529. It would be good to
understand the root cause though.

Signed-off-by: Mark Hindess <mark.hindess@gmail.com>

functional_test.go

@@ -442,12 +442,69 @@ func SaveProxy(t *testing.T, px string) {
 
 func setupFunctionalTest(t testing.TB) {
 	resetProxies(t)
+	ensureFullyReplicated(t, 60*time.Second, 5*time.Second)
 }
 
 func teardownFunctionalTest(t testing.TB) {
 	resetProxies(t)
 }
 
+func ensureFullyReplicated(t testing.TB, timeout time.Duration, retry time.Duration) {
+	config := NewTestConfig()
+	config.Metadata.Retry.Max = 5
+	config.Metadata.Retry.Backoff = 10 * time.Second
+	config.ClientID = "sarama-ensureFullyReplicated"
+	config.Version = V2_6_0_0
+
+	var testTopicNames []string
+	for topic := range testTopicDetails {
+		testTopicNames = append(testTopicNames, topic)
+	}
+
+	timer := time.NewTimer(timeout)
+	defer timer.Stop()
+	tick := time.NewTicker(retry)
+	defer tick.Stop()
+
+	for {
+		resp, err := func() (*MetadataResponse, error) {
+			client, err := NewClient(FunctionalTestEnv.KafkaBrokerAddrs, config)
+			if err != nil {
+				return nil, fmt.Errorf("failed to connect to kafka: %w", err)
+			}
+			defer client.Close()
+
+			controller, err := client.Controller()
+			if err != nil {
+				return nil, fmt.Errorf("failed to connect to kafka controller: %w", err)
+			}
+			defer controller.Close()
+			return controller.GetMetadata(&MetadataRequest{Version: 5, Topics: testTopicNames})
+		}()
+		if err != nil {
+			Logger.Printf("failed to get metadata during test setup: %v\n", err)
+		} else {
+			ok := true
+			for _, topic := range resp.Topics {
+				for _, partition := range topic.Partitions {
+					if len(partition.Isr) != 3 {
+						ok = false
+						Logger.Printf("topic %s/%d is not fully-replicated Isr=%v Offline=%v\n", topic.Name, partition.ID, partition.Isr, partition.OfflineReplicas)
+					}
+				}
+			}
+			if ok {
+				return
+			}
+		}
+		select {
+		case <-timer.C:
+			t.Fatalf("timeout waiting for test topics to be fully replicated")
+		case <-tick.C:
+		}
+	}
+}
+
 type kafkaVersion []int
 
 func (kv kafkaVersion) satisfies(other kafkaVersion) bool {