Use the crate mockall to mock the email service in integration tests

backend/Cargo.toml

@@ -56,3 +56,4 @@ thiserror = "2"
 axum-test = "17"
 cookie = "0.18"
 scraper = "0.23"
+mockall = "0.13"

backend/tests/http.rs

@@ -1,10 +1,11 @@
-use std::error::Error;
+use std::{error::Error, sync::Arc};
 
 use axum_test::TestServer;
 use cookie::Cookie;
+use mockall::predicate;
 use scraper::{ElementRef, Html, Selector};
 
-use recipes::app;
+use recipes::{app, email};
 use serde::Serialize;
 
 mod utils;
@@ -104,7 +105,18 @@ pub struct SignUpFormData {
 #[tokio::test]
 async fn sign_up() -> Result<(), Box<dyn Error>> {
     // Arrange.
-    let state = utils::common_state().await?;
+    let mut mock_email_service = utils::mock_email::MockEmailService::new();
+    mock_email_service
+        .expect_send_email()
+        .with(
+            predicate::eq("president@spaceball.planet"),
+            predicate::always(),
+            predicate::always(),
+        )
+        .times(1)
+        .returning(|_email, _title, _message| Ok(()));
+
+    let state = utils::common_state_with_email_service(Arc::new(mock_email_service)).await?;
     let server = TestServer::new(app::make_service(state))?;
 
     // Act.
@@ -122,7 +134,6 @@ async fn sign_up() -> Result<(), Box<dyn Error>> {
 
     let document = Html::parse_document(&response.text());
     assert_eq!(document.errors.len(), 0);
-    dbg!(response);
 
     Ok(())
 }

backend/tests/utils/mock_email.rs

@@ -1,23 +1,20 @@
 use std::sync::Arc;
 
-use recipes::email;
+use async_trait::async_trait;
+use mockall::{mock, predicate::*};
 
-pub struct MockEmailService;
+use crate::email;
 
-impl MockEmailService {
-    pub fn create_service() -> Arc<dyn email::EmailServiceTrait> {
-        Arc::new(Self {})
+mock! {
+    pub EmailService {}
+    #[async_trait]
+    impl email::EmailServiceTrait for EmailService {
+        async fn send_email(&self, email: &str, title: &str, message: &str)
+            -> Result<(), email::Error>;
     }
 }
 
-#[async_trait::async_trait]
-impl email::EmailServiceTrait for MockEmailService {
-    async fn send_email(
-        &self,
-        _email: &str,
-        _title: &str,
-        _message: &str,
-    ) -> Result<(), email::Error> {
-        Ok(())
-    }
+// Default email service: will crash if `send_email` method is called.
+pub fn new_mock_email_service() -> Arc<dyn email::EmailServiceTrait> {
+    Arc::new(MockEmailService::new())
 }

backend/tests/utils/mod.rs

@@ -1,10 +1,16 @@
-use std::error::Error;
+use std::{error::Error, sync::Arc};
 
-use recipes::{app, config, data::db, log};
+use recipes::{app, config, data::db, email, log};
 
-mod mock_email;
+pub mod mock_email;
 
 pub async fn common_state() -> Result<app::AppState, Box<dyn Error>> {
+    common_state_with_email_service(mock_email::new_mock_email_service()).await
+}
+
+pub async fn common_state_with_email_service(
+    email_service: Arc<dyn email::EmailServiceTrait>,
+) -> Result<app::AppState, Box<dyn Error>> {
     let db_connection = db::Connection::new_in_memory().await?;
     let config = config::Config::default();
     let log = log::Log::new_no_log();
@@ -12,7 +18,7 @@ pub async fn common_state() -> Result<app::AppState, Box<dyn Error>> {
         config,
         db_connection,
         log,
-        email_service: mock_email::MockEmailService::create_service(),
+        email_service,
     })
 }