update uncles return (#337)

rpc/eth_api.go

@@ -545,7 +545,7 @@ func formatBlock(
 		"gasUsed":          (*hexutil.Big)(gasUsed),
 		"timestamp":        hexutil.Uint64(header.Time.Unix()),
 		"transactions":     transactions.([]common.Hash),
-		"uncles":           nil,
+		"uncles":           []string{},
 	}
 }
 

tests/rpc_test.go

@@ -763,4 +763,5 @@ func TestEth_GetBlockByNumber(t *testing.T) {
 	err := json.Unmarshal(rpcRes.Result, &block)
 	require.NoError(t, err)
 	require.Equal(t, "0x0", block["extraData"].(string))
+	require.Equal(t, []interface{}{}, block["uncles"].([]interface{}))
 }