rpc: add GetStateHeight to client

pkg/rpc/client/rpc.go

@@ -374,6 +374,18 @@ func (c *Client) GetRawTransactionVerbose(hash util.Uint256) (*result.Transactio
 	return resp, nil
 }
 
+// GetStateHeight returns current validated and local node state height.
+func (c *Client) GetStateHeight() (*result.StateHeight, error) {
+	var (
+		params = request.NewRawParams()
+		resp   = new(result.StateHeight)
+	)
+	if err := c.performRequest("getstateheight", params, resp); err != nil {
+		return nil, err
+	}
+	return resp, nil
+}
+
 // GetStorageByID returns the stored value, according to the contract ID and the stored key.
 func (c *Client) GetStorageByID(id int32, key []byte) ([]byte, error) {
 	return c.getStorage(request.NewRawParams(id, base64.StdEncoding.EncodeToString(key)))

pkg/rpc/client/rpc_test.go

@@ -680,6 +680,21 @@ var rpcClientTestCases = map[string][]rpcClientTestCase{
 			},
 		},
 	},
+	"getstateheight": {
+		{
+			name: "positive",
+			invoke: func(c *Client) (interface{}, error) {
+				return c.GetStateHeight()
+			},
+			serverResponse: `{"jsonrpc":"2.0","id":1,"result":{"localrootindex":11646,"validatedrootindex":11645}}`,
+			result: func(c *Client) interface{} {
+				return &result.StateHeight{
+					Local:     11646,
+					Validated: 11645,
+				}
+			},
+		},
+	},
 	"getstorage": {
 		{
 			name: "by hash, positive",