refactor tests to re-use application build process

src/configuration.rs

@@ -5,21 +5,21 @@ use serde_aux::field_attributes::deserialize_number_from_string;
 use crate::domain::SubscriberEmail;
 
 
-#[derive(serde::Deserialize)]
+#[derive(Clone, serde::Deserialize)]
 pub struct Settings {
     pub database: DatabaseSettings,
     pub application: ApplicationSettings,
     pub email_client: EmailClientSettings,
 }
 
-#[derive(serde::Deserialize)]
+#[derive(Clone, serde::Deserialize)]
 pub struct ApplicationSettings {
     #[serde(deserialize_with = "deserialize_number_from_string")]
     pub port: u16,
     pub host: String,
 }
 
-#[derive(serde::Deserialize)]
+#[derive(Clone, serde::Deserialize)]
 pub struct DatabaseSettings {
     pub username: String,
     pub password: Secret<String>,
@@ -30,7 +30,7 @@ pub struct DatabaseSettings {
     pub require_ssl: bool,
 }
 
-#[derive(serde::Deserialize)]
+#[derive(Clone, serde::Deserialize)]
 pub struct EmailClientSettings {
     pub base_url: String,
     pub sender_email: String,

src/main.rs

@@ -1,9 +1,6 @@
-use std::net::TcpListener;
-use sqlx::postgres::PgPoolOptions;
-use zero2prod::startup::run;
+use zero2prod::startup::Application;
 use zero2prod::configuration::get_configuration;
 use zero2prod::telemetry::{get_subscriber, init_subscriber};
-use zero2prod::email_client::EmailClient;
 
 
 #[tokio::main]
@@ -14,27 +11,8 @@ async fn main() -> Result<(), std::io::Error> {
 
     // setup database connection
     let configuration = get_configuration().expect("Failed to read configuration.");
-    let connection_pool = PgPoolOptions::new()
-        .connect_lazy_with(configuration.database.with_db()
-    );
-    let sender_email = configuration.email_client.sender()
-        .expect("Invalid sender email address.");
-    let timeout = configuration.email_client.timeout();
-    let email_client = EmailClient::new(
-        configuration.email_client.base_url,
-        sender_email,
-        configuration.email_client.authorization_token,
-        timeout,
-    );
-    let address = format!(
-        "{}:{}",
-        configuration.application.host,
-        configuration.application.port,
-    );
-    let listener = TcpListener::bind(address)?;
-
-    // run the server
-    run(listener, connection_pool, email_client)?.await?;
+    let server = Application::build(configuration).await?;
+    server.run_until_stopped().await?;
     Ok(())
 }
 

src/startup.rs

@@ -1,13 +1,79 @@
-use std::net::TcpListener;
-use actix_web::{web, App, HttpServer};
+use crate::configuration::{DatabaseSettings, Settings};
+use crate::email_client::EmailClient;
+use crate::routes::{health_check, subscribe};
 use actix_web::dev::Server;
+use actix_web::{web, App, HttpServer};
+use sqlx::postgres::PgPoolOptions;
 use sqlx::PgPool;
+use std::net::TcpListener;
 use tracing_actix_web::TracingLogger;
-use crate::routes::{health_check, subscribe};
-use crate::email_client::EmailClient;
 
+pub struct Application {
+    port: u16,
+    server: Server,
+}
+
+impl Application {
+    pub async fn build(configuration: Settings) -> Result<Self, std::io::Error> {
+        let connection_pool = get_connection_pool(&configuration.database);
+        let sender_email = configuration
+            .email_client
+            .sender()
+            .expect("Invalid sender email address.");
+        let timeout = configuration.email_client.timeout();
+        let email_client = EmailClient::new(
+            configuration.email_client.base_url,
+            sender_email,
+            configuration.email_client.authorization_token,
+            timeout,
+        );
+        let address = format!(
+            "{}:{}",
+            configuration.application.host, configuration.application.port,
+        );
+        let listener = TcpListener::bind(address)?;
+        let port = listener.local_addr().unwrap().port();
+        let server = run(listener, connection_pool, email_client)?;
+        Ok(Self { port, server })
+    }
+
+    pub fn port(&self) -> u16 {
+        self.port
+    }
+
+    pub async fn run_until_stopped(self) -> Result<(), std::io::Error> {
+        self.server.await
+    }
+}
+
+pub async fn build(configuration: Settings) -> Result<Server, std::io::Error> {
+    let connection_pool = get_connection_pool(&configuration.database);
+    let sender_email = configuration
+        .email_client
+        .sender()
+        .expect("Invalid sender email address.");
+    let timeout = configuration.email_client.timeout();
+    let email_client = EmailClient::new(
+        configuration.email_client.base_url,
+        sender_email,
+        configuration.email_client.authorization_token,
+        timeout,
+    );
+    let address = format!(
+        "{}:{}",
+        configuration.application.host, configuration.application.port,
+    );
+    let listener = TcpListener::bind(address)?;
+
+    // run the server
+    run(listener, connection_pool, email_client)
+}
+
+pub fn get_connection_pool(config: &DatabaseSettings) -> PgPool {
+    PgPoolOptions::new().connect_lazy_with(config.with_db())
+}
 
-pub fn run(
+fn run(
     listener: TcpListener,
     db_pool: PgPool,
     email_client: EmailClient,

tests/api/health_check.rs

@@ -0,0 +1,20 @@
+use crate::helpers::spawn_app;
+
+#[tokio::test]
+async fn health_check_works() {
+    // Arrange
+    let app = spawn_app().await;
+    let client = reqwest::Client::new();
+
+    // Act
+    let response = client
+        // Use the returned application address
+        .get(&format!("{}/health_check", &app.address))
+        .send()
+        .await
+        .expect("Failed to execute request.");
+
+    // Assert
+    assert!(response.status().is_success());
+    assert_eq!(Some(0), response.content_length());
+}

tests/api/helpers.rs

@@ -0,0 +1,73 @@
+use once_cell::sync::Lazy;
+use sqlx::{Connection, Executor, PgConnection, PgPool};
+use sqlx::postgres::PgPoolOptions;
+use uuid::Uuid;
+use zero2prod::configuration::{DatabaseSettings, get_configuration};
+use zero2prod::startup::{Application, get_connection_pool};
+use zero2prod::telemetry::{get_subscriber, init_subscriber};
+
+pub struct TestApp {
+    pub address: String,
+    pub db_pool: PgPool,
+}
+
+static TRACING: Lazy<()> = Lazy::new(|| {
+    let default_filter_level = "info".to_string();
+    let subscriber_name = "test".to_string();
+    if std::env::var("TEST_LOG").is_ok() {
+        let subscriber = get_subscriber(subscriber_name, default_filter_level, std::io::stdout);
+        init_subscriber(subscriber);
+    } else {
+        let subscriber = get_subscriber(subscriber_name, default_filter_level, std::io::sink);
+        init_subscriber(subscriber);
+    };
+});
+
+// Launch our application in the background
+pub async fn spawn_app() -> TestApp {
+    // The first time `initialize` is invoked the code in `TRACING` is executed.
+    // All other invocations will instead skip execution.
+    Lazy::force(&TRACING);
+
+    let configuration = {
+        let mut c = get_configuration().expect("Failed to read configuration.");
+        // Use a different database for each test case
+        c.database.name = Uuid::new_v4().to_string();
+        // Use a random OS-assigned port
+        c.application.port = 0;
+        c
+    };
+
+    // Create and migrate the database
+    configure_database(&configuration.database).await;
+
+    // Launch the application as a background task
+    let application = Application::build(configuration.clone()).await.expect("Failed to build application.");
+    let address = format!("http://127.0.0.1:{}", application.port());
+    let _ = tokio::spawn(application.run_until_stopped());
+    TestApp {
+        address,
+        db_pool: get_connection_pool(&configuration.database),
+    }
+}
+
+async fn configure_database(config: &DatabaseSettings) -> PgPool {
+    // Create database
+    let mut connection =
+        PgConnection::connect_with(&config.without_db())
+            .await
+            .expect("Failed to connect to Postgres");
+    connection
+        .execute(&*format!(r#"CREATE DATABASE "{}";"#, config.name))
+        .await
+        .expect("Failed to create database.");
+
+    // Migrate database
+    let connection_pool = PgPoolOptions::new().connect_lazy_with(config.with_db());
+    sqlx::migrate!("./migrations")
+        .run(&connection_pool)
+        .await
+        .expect("Failed to migrate the database");
+
+    connection_pool
+}

tests/api/main.rs

@@ -0,0 +1,3 @@
+mod helpers;
+mod health_check;
+mod subscriptions;

tests/api/subscriptions.rs

@@ -0,0 +1,93 @@
+use crate::helpers::spawn_app;
+
+#[tokio::test]
+async fn subscribe_returns_a_200_for_valid_form_data() {
+    // Arrange
+    let app = spawn_app().await;
+    let client = reqwest::Client::new();
+    let body = "name=le%20guin&email=ursula_le_guin%40gmail.com";
+
+    // Act
+    let response = client
+        .post(&format!("{}/subscriptions", &app.address))
+        .header("Content-Type", "application/x-www-form-urlencoded")
+        .body(body)
+        .send()
+        .await
+        .expect("Failed to execute request.");
+
+    // Assert
+    assert_eq!(200, response.status().as_u16());
+
+    let saved = sqlx::query!("SELECT email, name FROM subscriptions",)
+        .fetch_one(&app.db_pool)
+        .await
+        .expect("Failed to fetch saved subscription.");
+
+    assert_eq!(saved.email, "[email protected]");
+    assert_eq!(saved.name, "le guin");
+}
+
+#[tokio::test]
+async fn subscribe_returns_a_400_when_data_is_missing() {
+    // Arrange
+    let app = spawn_app().await;
+    let client = reqwest::Client::new();
+    let test_cases = vec![
+        ("name=le%20guin", "missing the email"),
+        ("email=ursula_le_guin%40gmail.com", "missing the name"),
+        ("", "missing both name and email"),
+    ];
+
+    for (invalid_body, error_message) in test_cases {
+        // Act
+        let response = client
+            .post(&format!("{}/subscriptions", &app.address))
+            .header("Content-Type", "application/x-www-form-urlencoded")
+            .body(invalid_body)
+            .send()
+            .await
+            .expect("Failed to execute request.");
+
+        // 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
+        );
+    }
+}
+
+
+#[tokio::test]
+async fn subscribe_returns_a_400_when_fields_are_present_but_invalid() {
+    // Arrange
+    let app = spawn_app().await;
+    let client = reqwest::Client::new();
+    let test_cases = vec![
+        ("name=&email=ursula_le_guin%40gmail.com", "empty name"),
+        ("name=Ursula&email=", "empty email"),
+        ("name=&email=", "empty name and email"),
+    ];
+
+    for (body, description) in test_cases {
+        // Act
+        let response = client
+            .post(&format!("{}/subscriptions", &app.address))
+            .header("Content-Type", "application/x-www-form-urlencoded")
+            .body(body)
+            .send()
+            .await
+            .expect("Failed to execute request.");
+
+        // Assert
+        assert_eq!(
+            400,
+            response.status().as_u16(),
+            "The API returned a 400 when the payload was {}.",
+            description
+        );
+    }
+}