clientv3/concurrency: Expose examples close to the source-code.

tests/integration/clientv3/concurrency/main_test.go

@@ -15,30 +15,28 @@
 package concurrency_test
 
 import (
-	"fmt"
 	"os"
 	"testing"
-	"time"
 
 	"go.etcd.io/etcd/tests/v3/integration"
 	"go.etcd.io/etcd/v3/pkg/testutil"
 )
 
-var endpoints []string
+var lazyCluster = integration.NewLazyCluster()
 
-// TestMain sets up an etcd cluster for running the examples.
+func exampleEndpoints() []string { return lazyCluster.EndpointsV3() }
+
+func forUnitTestsRunInMockedContext(mocking func(), example func()) {
+	// For integration tests runs in the provided environment
+	example()
+}
+
+// TestMain sets up an etcd cluster if running the examples.
 func TestMain(m *testing.M) {
-	cfg := integration.ClusterConfig{Size: 1}
-	clus := integration.NewClusterV3(nil, &cfg)
-	endpoints = []string{clus.Client(0).Endpoints()[0]}
 	v := m.Run()
-	clus.Terminate(nil)
-	if err := testutil.CheckAfterTest(time.Second); err != nil {
-		fmt.Fprintf(os.Stderr, "%v", err)
-		os.Exit(1)
-	}
-	if v == 0 && testutil.CheckLeakedGoroutine() {
-		os.Exit(1)
+	lazyCluster.Terminate()
+	if v == 0 {
+		testutil.MustCheckLeakedGoroutine()
 	}
 	os.Exit(v)
 }