light: wait for tendermint node to start before running example test (#6744)

light/example_test.go

@@ -2,7 +2,6 @@ package light_test
 
 import (
 	"context"
-	"fmt"
 	"io/ioutil"
 	stdlog "log"
 	"os"
@@ -19,23 +18,22 @@ import (
 	rpctest "github.com/tendermint/tendermint/rpc/test"
 )
 
-// Automatically getting new headers and verifying them.
-func ExampleClient_Update() {
+// Manually getting light blocks and verifying them.
+func ExampleClient() {
 	ctx, cancel := context.WithCancel(context.Background())
 	defer cancel()
-	conf := rpctest.CreateConfig("ExampleClient_Update")
+	conf := rpctest.CreateConfig("ExampleClient_VerifyLightBlockAtHeight")
+	logger := log.TestingLogger()
 
 	// Start a test application
 	app := kvstore.NewApplication()
+
 	_, closer, err := rpctest.StartTendermint(ctx, conf, app, rpctest.SuppressStdout)
 	if err != nil {
 		stdlog.Fatal(err)
 	}
 	defer func() { _ = closer(ctx) }()
 
-	// give Tendermint time to generate some blocks
-	time.Sleep(5 * time.Second)
-
 	dbDir, err := ioutil.TempDir("", "light-client-example")
 	if err != nil {
 		stdlog.Fatal(err)
@@ -49,6 +47,9 @@ func ExampleClient_Update() {
 		stdlog.Fatal(err)
 	}
 
+	// give Tendermint time to generate some blocks
+	time.Sleep(5 * time.Second)
+
 	block, err := primary.LightBlock(ctx, 2)
 	if err != nil {
 		stdlog.Fatal(err)
@@ -59,8 +60,7 @@ func ExampleClient_Update() {
 		stdlog.Fatal(err)
 	}
 
-	c, err := light.NewClient(
-		ctx,
+	c, err := light.NewClient(ctx,
 		chainID,
 		light.TrustOptions{
 			Period: 504 * time.Hour, // 21 days
@@ -70,7 +70,7 @@ func ExampleClient_Update() {
 		primary,
 		[]provider.Provider{primary}, // NOTE: primary should not be used here
 		dbs.New(db),
-		light.Logger(log.TestingLogger()),
+		light.Logger(logger),
 	)
 	if err != nil {
 		stdlog.Fatal(err)
@@ -81,91 +81,26 @@ func ExampleClient_Update() {
 		}
 	}()
 
+	// wait for a few more blocks to be produced
 	time.Sleep(2 * time.Second)
 
-	h, err := c.Update(ctx, time.Now())
-	if err != nil {
-		stdlog.Fatal(err)
-	}
-
-	if h != nil && h.Height > 2 {
-		fmt.Println("successful update")
-	} else {
-		fmt.Println("update failed")
-	}
-}
-
-// Manually getting light blocks and verifying them.
-func ExampleClient_VerifyLightBlockAtHeight() {
-	ctx, cancel := context.WithCancel(context.Background())
-	defer cancel()
-	conf := rpctest.CreateConfig("ExampleClient_VerifyLightBlockAtHeight")
-
-	// Start a test application
-	app := kvstore.NewApplication()
-
-	_, closer, err := rpctest.StartTendermint(ctx, conf, app, rpctest.SuppressStdout)
-	if err != nil {
-		stdlog.Fatal(err)
-	}
-	defer func() { _ = closer(ctx) }()
-
-	// give Tendermint time to generate some blocks
-	time.Sleep(5 * time.Second)
-
-	dbDir, err := ioutil.TempDir("", "light-client-example")
-	if err != nil {
-		stdlog.Fatal(err)
-	}
-	defer os.RemoveAll(dbDir)
-
-	chainID := conf.ChainID()
-
-	primary, err := httpp.New(chainID, conf.RPC.ListenAddress)
-	if err != nil {
-		stdlog.Fatal(err)
-	}
-
-	block, err := primary.LightBlock(ctx, 2)
-	if err != nil {
-		stdlog.Fatal(err)
-	}
-
-	db, err := dbm.NewGoLevelDB("light-client-db", dbDir)
-	if err != nil {
-		stdlog.Fatal(err)
-	}
-
-	c, err := light.NewClient(ctx,
-		chainID,
-		light.TrustOptions{
-			Period: 504 * time.Hour, // 21 days
-			Height: 2,
-			Hash:   block.Hash(),
-		},
-		primary,
-		[]provider.Provider{primary}, // NOTE: primary should not be used here
-		dbs.New(db),
-		light.Logger(log.TestingLogger()),
-	)
+	// veify the block at height 3
+	_, err = c.VerifyLightBlockAtHeight(context.Background(), 3, time.Now())
 	if err != nil {
 		stdlog.Fatal(err)
 	}
-	defer func() {
-		if err := c.Cleanup(); err != nil {
-			stdlog.Fatal(err)
-		}
-	}()
 
-	_, err = c.VerifyLightBlockAtHeight(context.Background(), 3, time.Now())
+	// retrieve light block at height 3
+	_, err = c.TrustedLightBlock(3)
 	if err != nil {
 		stdlog.Fatal(err)
 	}
 
-	h, err := c.TrustedLightBlock(3)
+	// update to the latest height
+	lb, err := c.Update(ctx, time.Now())
 	if err != nil {
 		stdlog.Fatal(err)
 	}
 
-	fmt.Println("got header", h.Height)
+	logger.Info("verified light block", "light-block", lb)
 }

light/light_test.go

@@ -17,6 +17,7 @@ import (
 	httpp "github.com/tendermint/tendermint/light/provider/http"
 	dbs "github.com/tendermint/tendermint/light/store/db"
 	rpctest "github.com/tendermint/tendermint/rpc/test"
+	"github.com/tendermint/tendermint/types"
 )
 
 // NOTE: these are ports of the tests from example_test.go but
@@ -48,7 +49,8 @@ func TestClientIntegration_Update(t *testing.T) {
 	primary, err := httpp.New(chainID, conf.RPC.ListenAddress)
 	require.NoError(t, err)
 
-	block, err := primary.LightBlock(ctx, 2)
+	// give Tendermint time to generate some blocks
+	block, err := waitForBlock(ctx, primary, 2)
 	require.NoError(t, err)
 
 	db, err := dbm.NewGoLevelDB("light-client-db", dbDir)
@@ -71,7 +73,9 @@ func TestClientIntegration_Update(t *testing.T) {
 
 	defer func() { require.NoError(t, c.Cleanup()) }()
 
-	time.Sleep(2 * time.Second)
+	// ensure Tendermint is at height 3 or higher
+	_, err = waitForBlock(ctx, primary, 3)
+	require.NoError(t, err)
 
 	h, err := c.Update(ctx, time.Now())
 	require.NoError(t, err)
@@ -94,9 +98,6 @@ func TestClientIntegration_VerifyLightBlockAtHeight(t *testing.T) {
 	require.NoError(t, err)
 	defer func() { require.NoError(t, closer(ctx)) }()
 
-	// give Tendermint time to generate some blocks
-	time.Sleep(5 * time.Second)
-
 	dbDir, err := ioutil.TempDir("", "light-client-test-verify-example")
 	require.NoError(t, err)
 	defer os.RemoveAll(dbDir)
@@ -106,7 +107,8 @@ func TestClientIntegration_VerifyLightBlockAtHeight(t *testing.T) {
 	primary, err := httpp.New(chainID, conf.RPC.ListenAddress)
 	require.NoError(t, err)
 
-	block, err := primary.LightBlock(ctx, 2)
+	// give Tendermint time to generate some blocks
+	block, err := waitForBlock(ctx, primary, 2)
 	require.NoError(t, err)
 
 	db, err := dbm.NewGoLevelDB("light-client-db", dbDir)
@@ -128,6 +130,10 @@ func TestClientIntegration_VerifyLightBlockAtHeight(t *testing.T) {
 
 	defer func() { require.NoError(t, c.Cleanup()) }()
 
+	// ensure Tendermint is at height 3 or higher
+	_, err = waitForBlock(ctx, primary, 3)
+	require.NoError(t, err)
+
 	_, err = c.VerifyLightBlockAtHeight(ctx, 3, time.Now())
 	require.NoError(t, err)
 
@@ -136,3 +142,23 @@ func TestClientIntegration_VerifyLightBlockAtHeight(t *testing.T) {
 
 	require.EqualValues(t, 3, h.Height)
 }
+
+func waitForBlock(ctx context.Context, p provider.Provider, height int64) (*types.LightBlock, error) {
+	for {
+		block, err := p.LightBlock(ctx, height)
+		switch err {
+		case nil:
+			return block, nil
+		// node isn't running yet, wait 1 second and repeat
+		case provider.ErrNoResponse, provider.ErrHeightTooHigh:
+			timer := time.NewTimer(1 * time.Second)
+			select {
+			case <-ctx.Done():
+				return nil, ctx.Err()
+			case <-timer.C:
+			}
+		default:
+			return nil, err
+		}
+	}
+}