test: add unhappy case for email client

src/email_client.rs

@@ -40,8 +40,7 @@ impl EmailClient {
             html_body: html_content,
             text_body: text_content,
         };
-        let _builder = self
-            .http_client
+        self.http_client
             .post(&url)
             .header(
                 "X-Postmark-Server-Token",
@@ -49,7 +48,8 @@ impl EmailClient {
             )
             .json(&request_body)
             .send()
-            .await?;
+            .await?
+            .error_for_status()?;
         Ok(())
     }
 }
@@ -68,13 +68,13 @@ mod tests {
 
     use crate::domain::SubscriberEmail;
     use crate::email_client::EmailClient;
+    use claims::{assert_err, assert_ok};
     use fake::faker::internet::en::SafeEmail;
     use fake::faker::lorem::en::{Paragraph, Sentence};
     use fake::{Fake, Faker};
     use secrecy::Secret;
     use wiremock::matchers::{any, header, header_exists, method, path};
     use wiremock::{Mock, MockServer, Request, ResponseTemplate};
-    use claims::assert_ok;
 
     struct SendEmailBodyMatcher;
 
@@ -103,11 +103,7 @@ mod tests {
         // Arrange
         let mock_server = MockServer::start().await;
         let sender = SubscriberEmail::parse(SafeEmail().fake()).unwrap();
-        let email_client = EmailClient::new(
-            mock_server.uri(),
-            sender,
-            Secret::new(Faker.fake())
-        );
+        let email_client = EmailClient::new(mock_server.uri(), sender, Secret::new(Faker.fake()));
 
         let subscriber_email = SubscriberEmail::parse(SafeEmail().fake()).unwrap();
         let subject: String = Sentence(1..2).fake();
@@ -157,4 +153,31 @@ mod tests {
         // Assert
         // Mock expectations are checked on drop
     }
+
+    #[tokio::test]
+    async fn send_email_fails_if_the_server_returns_500() {
+        // Arrange
+        let mock_server = MockServer::start().await;
+        let sender = SubscriberEmail::parse(SafeEmail().fake()).unwrap();
+        let email_client = EmailClient::new(mock_server.uri(), sender, Secret::new(Faker.fake()));
+
+        let subscriber_email = SubscriberEmail::parse(SafeEmail().fake()).unwrap();
+        let subject: String = Sentence(1..2).fake();
+        let content: String = Paragraph(1..10).fake();
+
+        Mock::given(any())
+            // Not a 200 anymore!
+            .respond_with(ResponseTemplate::new(500))
+            .expect(1)
+            .mount(&mock_server)
+            .await;
+
+        // Act
+        let outcome = email_client
+            .send_email(subscriber_email, &subject, &content, &content)
+            .await;
+
+        // Assert
+        assert_err!(outcome);
+    }
 }