test: write tests

Finished chapter 3.5

tests/health_check.rs

@@ -0,0 +1,25 @@
+use std::net::SocketAddr;
+
+use tokio::net::TcpListener;
+use zero2prod::app;
+
+#[tokio::test]
+async fn health_check() {
+    spawn_app();
+    let client = reqwest::Client::new();
+    let response = client
+        .get("http://localhost:8000/health_check")
+        .send()
+        .await
+        .expect("Failed to execute request.");
+    assert!(response.status().is_success());
+    assert_eq!(Some(0), response.content_length());
+}
+
+fn spawn_app() {
+    let addr = SocketAddr::from(([127, 0, 0, 1], 8000));
+    let _ = tokio::spawn(async move {
+        let listener = TcpListener::bind(addr).await.unwrap();
+        axum::serve(listener, app()).await.unwrap();
+    });
+}