Add tests for Cluster Reroute API

This commit adds some more tests to the Cluster Reroute API, while
revisiting #1560.

Close #1560

Author: olivere

cluster_reroute_test.go

@@ -7,6 +7,7 @@ package elastic
 import (
 	"context"
 	"net/url"
+	"strings"
 	"testing"
 )
 
@@ -51,8 +52,18 @@ func TestClusterRerouteURLs(t *testing.T) {
 }
 
 func TestClusterReroute(t *testing.T) {
+	// client := setupTestClientAndCreateIndex(t, SetTraceLog(log.New(os.Stdout, "", 0)))
 	client := setupTestClientAndCreateIndex(t)
 
+	t.Run("Commands", func(t *testing.T) {
+		testClusterRerouteWithCommands(client, t)
+	})
+	t.Run("NoBody", func(t *testing.T) {
+		testClusterRerouteWithoutBody(client, t)
+	})
+}
+
+func testClusterRerouteWithCommands(client *Client, t *testing.T) {
 	// Get cluster nodes
 	var nodes []string
 	{
@@ -92,3 +103,23 @@ func TestClusterReroute(t *testing.T) {
 		t.Fatalf("expected Status=%d, have %d", want, have)
 	}
 }
+
+func testClusterRerouteWithoutBody(client *Client, t *testing.T) {
+	// Perform a nop cluster reroute
+	res, err := client.ClusterReroute().
+		DryRun(true).
+		Pretty(true).
+		RetryFailed(true).
+		MasterTimeout("10s").
+		Do(context.Background())
+	// Expect an error here: We just test if it's of a specific kind
+	if err == nil {
+		t.Fatal("expected an error, got nil")
+	}
+	if res != nil {
+		t.Fatalf("expected res to be != nil; got: %v", res)
+	}
+	if !strings.Contains(err.Error(), "missing allocate commands or raw body") {
+		t.Fatalf("expected Error~=%s, have %s", "missing allocate commands or raw body", err.Error())
+	}
+}