Refactor tests.

src/routes/newsletters.rs

@@ -1,12 +1,12 @@
 use actix_web::{web, HttpResponse};
 
-#[derive(serde::Serialize)]
+#[derive(serde::Deserialize)]
 pub struct BodyData {
     title: String,
     content: Content,
 }
 
-#[derive(serde::Serialize)]
+#[derive(serde::Deserialize)]
 pub struct Content {
     html: String,
     text: String,

tests/api/helpers.rs

@@ -43,6 +43,15 @@ impl TestApp {
             .expect("Failed to execute request.")
     }
 
+    pub async fn post_newsletters(&self, body: serde_json::Value) -> reqwest::Response {
+        reqwest::Client::new()
+            .post(&format!("{}/newsletters", &self.address))
+            .json(&body)
+            .send()
+            .await
+            .expect("Failed to execute request.")
+    }
+
     /// Extract the confirmation links embedded in the request to the email API.
     pub fn get_confirmation_links(&self, email_request: &wiremock::Request) -> ConfirmationLinks {
         let body: serde_json::Value = serde_json::from_slice(&email_request.body).unwrap();

tests/api/newsletter.rs

@@ -56,12 +56,7 @@ async fn newsletters_are_not_delivered_to_unconfirmed_subscribers() {
             "html": "<p>Newsletter body as HTML</p>",
         }
     });
-    let response = reqwest::Client::new()
-        .post(&format!("{}/newsletters", &app.address))
-        .json(&newsletter_request_body)
-        .send()
-        .await
-        .expect("Failed to execute request.");
+    let response = app.post_newsletters(newsletter_request_body).await;
 
     // Assert
     assert_eq!(response.status().as_u16(), 200);
@@ -89,14 +84,45 @@ async fn newsletters_are_delivered_to_confirmed_subscribers() {
             "html": "<p>Newsletter body as HTML</p>",
         }
     });
-    let response = reqwest::Client::new()
-        .post(&format!("{}/newsletters", &app.address))
-        .json(&newsletter_request_body)
-        .send()
-        .await
-        .expect("Failed to execute request.");
+    let response = app.post_newsletters(newsletter_request_body).await;
 
     // Assert
     assert_eq!(response.status().as_u16(), 200);
     // Mock verifies on Drop that we have sent the newsletter email
 }
+
+#[actix_rt::test]
+async fn newsletters_returns_400_for_invalid_data() {
+    // Arrange
+    let app = spawn_app().await;
+    let test_cases = vec![
+        (
+            serde_json::json!({
+                "content": {
+                    "text": "Newsletter body as plain text",
+                    "html": "<p>Newsletter body as HTML</p>",
+                }
+            }),
+            "missing title",
+        ),
+        (
+            serde_json::json!({
+                "title": "Newsletter!"
+            }),
+            "missing content",
+        ),
+    ];
+
+    for (invalid_body, error_message) in test_cases {
+        let response = app.post_newsletters(invalid_body).await;
+
+        // Assert
+        assert_eq!(
+            400,
+            response.status().as_u16(),
+            // Additional customised error message on test failure
+            "The API did not fail with 400 Bad Request when the payload was {}.",
+            error_message
+        );
+    }
+}