fix tests

Cargo.toml

@@ -16,3 +16,6 @@ reqwest = "0.10.0"
 urlencoding = "1.0.0"
 json = "0.12.0"
 futures = "0.3.1"
+
+[dev-dependencies]
+tokio-test = "0.2.0"

README.md

@@ -9,6 +9,8 @@ NOTE: From version 1.1.0 dingtalk uses reqwest 0.10.0's async/await API.
 
 Sample 1:
 ```rust
+use dingtalk::DingTalk;
+
 #[tokio::main]
 pub async fn main() -> Result<(), Box<dyn std::error::Error>> {
     let dt = DingTalk::new("<token>", "");
@@ -18,6 +20,8 @@ pub async fn main() -> Result<(), Box<dyn std::error::Error>> {
 }
 ```
 
+Need use crate: `tokio = { version = "0.2.6", features = ["full"] }`.
+
 Sample 2 (Read token from file):
 ```rust
 #[tokio::main]

src/lib.rs

@@ -497,7 +497,7 @@ fn calc_hmac_sha256(key: &[u8], message: &[u8]) -> MacResult {
 
 #[test]
 fn run_all_tests() {
-    futures::executor::block_on(_test_send()).unwrap();
+    tokio_test::block_on(_test_send()).unwrap();
 }
 
 async fn _test_send() -> XResult<()> {