Parse data from incoming request

tests/health_check.rs

@@ -88,6 +88,34 @@ async fn subscribe_returns_a_422_when_data_is_missing() {
     }
 }
 
+#[tokio::test]
+async fn subscribe_returns_a_400_when_fields_are_present_but_invalid() {
+    let app = spawn_app().await;
+    let client = reqwest::Client::new();
+
+    let test_cases = [
+        ("name=&email=alphonse.paix%40outlook.com", "empty name"),
+        ("name=Alphonse&email=", "empty email"),
+        ("name=Alphonse&email=not-an-email", "invalid email"),
+    ];
+    for (body, description) in test_cases {
+        let response = client
+            .post(format!("http://{}/subscriptions", app.address))
+            .header("Content-Type", "application/x-www-form-urlencoded")
+            .body(body)
+            .send()
+            .await
+            .unwrap();
+
+        assert_eq!(
+            400,
+            response.status().as_u16(),
+            "the API did not return a 400 Bad Request when the payload had an {}.",
+            description
+        );
+    }
+}
+
 async fn spawn_app() -> TestApp {
     Lazy::force(&TRACING);