Add a test that after snapshot is applied, GraphQL schema is refreshed (

#8619)

After snapshot stream is received from other running alpha,
ensure that the new graphql schema is loaded into memory .

Sequence of steps in the test:
 * Stop one alpha container 
 * Add data into cluster + apply new graphql schema 
 * Start alpha container
 * Check whether the newly started alpha got graphql schema in snapshot.

testutil/docker.go

@@ -271,3 +271,28 @@ func DockerInspect(containerID string) (types.ContainerJSON, error) {
 	x.Check(err)
 	return cli.ContainerInspect(context.Background(), containerID)
 }
+
+// checkHealthContainer checks health of container and determines wheather container is ready to accept request
+func CheckHealthContainer(socketAddrHttp string) error {
+	var err error
+	var resp *http.Response
+	url := "http://" + socketAddrHttp + "/health"
+	for i := 0; i < 30; i++ {
+		resp, err = http.Get(url)
+		if err == nil && resp.StatusCode == http.StatusOK {
+			return nil
+		}
+		var body []byte
+		if resp != nil && resp.Body != nil {
+			body, err = ioutil.ReadAll(resp.Body)
+			if err != nil {
+				return err
+			}
+			resp.Body.Close()
+		}
+		fmt.Printf("health check for container failed: %v. Response: %q. Retrying...\n", err, body)
+		time.Sleep(time.Second)
+
+	}
+	return err
+}

testutil/schema.go

@@ -17,8 +17,11 @@
 package testutil
 
 import (
+	"bytes"
 	"context"
+	"encoding/json"
 	"fmt"
+	"net/http"
 	"testing"
 
 	"github.com/stretchr/testify/require"
@@ -133,3 +136,40 @@ func VerifySchema(t *testing.T, dg *dgo.Dgraph, opts SchemaOptions) {
 
 	CompareJSON(t, GetFullSchemaJSON(opts), string(resp.GetJson()))
 }
+
+func UpdateGQLSchema(t *testing.T, sockAddrHttp, schema string) {
+	query := `mutation updateGQLSchema($sch: String!) {
+		updateGQLSchema(input: { set: { schema: $sch }}) {
+			gqlSchema {
+				schema
+			}
+		}
+	}`
+	adminUrl := "http://" + sockAddrHttp + "/admin"
+
+	params := GraphQLParams{
+		Query: query,
+		Variables: map[string]interface{}{
+			"sch": schema,
+		},
+	}
+	b, err := json.Marshal(params)
+	require.NoError(t, err)
+	resp, err := http.Post(adminUrl, "application/json", bytes.NewBuffer(b))
+	require.NoError(t, err)
+	defer resp.Body.Close()
+}
+
+func GetGQLSchema(t *testing.T, sockAddrHttp string) string {
+	query := `{getGQLSchema {schema}}`
+	params := GraphQLParams{Query: query}
+	b, err := json.Marshal(params)
+	adminUrl := "http://" + sockAddrHttp + "/admin"
+	require.NoError(t, err)
+	resp, err := http.Post(adminUrl, "application/json", bytes.NewBuffer(b))
+	require.NoError(t, err)
+	defer resp.Body.Close()
+	var data interface{}
+	require.NoError(t, json.NewDecoder(resp.Body).Decode(&data))
+	return JsonGet(data, "data", "getGQLSchema", "schema").(string)
+}

worker/snapshot_test.go

@@ -81,7 +81,10 @@ func TestSnapshot(t *testing.T) {
 	require.NoError(t, err)
 
 	// Wait for the container to start.
-	time.Sleep(time.Second * 2)
+	err = testutil.CheckHealthContainer(testutil.ContainerAddr("alpha2", 8080))
+	if err != nil {
+		t.Fatalf("error while getting alpha container health: %v", err)
+	}
 	dg2, err := testutil.DgraphClient(testutil.ContainerAddr("alpha2", 9080))
 	if err != nil {
 		t.Fatalf("Error while getting a dgraph client: %v", err)
@@ -99,17 +102,27 @@ func TestSnapshot(t *testing.T) {
 		})
 		require.NoError(t, err)
 	}
+	const testSchema = "type Person { name: String }"
+	// uploading new schema while alpha2 is not running so we can test whether the stopped alpha gets new schema in snapshot
+	testutil.UpdateGQLSchema(t, testutil.SockAddrHttp, testSchema)
 	_ = waitForSnapshot(t, snapshotTs)
 
 	t.Logf("Starting alpha2.\n")
 	err = testutil.DockerRun("alpha2", testutil.Start)
 	require.NoError(t, err)
+	err = testutil.CheckHealthContainer(testutil.ContainerAddr("alpha2", 8080))
+	if err != nil {
+		t.Fatalf("error while getting alpha container health: %v", err)
+	}
 
 	dg2, err = testutil.DgraphClient(testutil.ContainerAddr("alpha2", 9080))
 	if err != nil {
 		t.Fatalf("Error while getting a dgraph client: %v", err)
 	}
 	verifySnapshot(t, dg2, 400)
+	resp := testutil.GetGQLSchema(t, testutil.ContainerAddr("alpha2", 8080))
+	// comparing uploaded graphql schema and schema acquired from stopped container
+	require.Equal(t, testSchema, resp)
 }
 
 func verifySnapshot(t *testing.T, dg *dgo.Dgraph, num int) {