Add .env file and check db in the /subscriptions happy path test

.env

@@ -0,0 +1 @@
+DATABASE_URL="postgres://postgres:password@localhost:5432/newsletter"

src/configuration.rs

@@ -23,3 +23,12 @@ pub fn get_configuration() -> Result<Settings, config::ConfigError> {
 
     settings.try_deserialize::<Settings>()
 }
+
+impl DatabaseSettings {
+    pub fn connection_string(&self) -> String {
+        format!(
+            "postgres://{}:{}@{}:{}/{}",
+            self.username, self.password, self.host, self.port, self.database_name
+        )
+    }
+}

tests/health_check.rs

@@ -1,5 +1,8 @@
 use std::net::TcpListener;
 
+use sqlx::{Connection, PgConnection};
+use zero2prod::configuration::get_configuration;
+
 #[tokio::test]
 async fn health_check_works() {
     // Arrange
@@ -22,6 +25,11 @@ async fn health_check_works() {
 async fn subscribe_returns_a_200_for_valid_form_data() {
     // Arrange
     let app_address = spawn_app();
+    let configuration = get_configuration().expect("Failed to read configuration");
+    let connection_string = configuration.database.connection_string();
+    let mut connection = PgConnection::connect(&connection_string)
+        .await
+        .expect("Failed to connect to Postgres.");
     let client = reqwest::Client::new();
 
     // Act
@@ -36,6 +44,14 @@ async fn subscribe_returns_a_200_for_valid_form_data() {
 
     // Assert
     assert_eq!(200, response.status().as_u16());
+
+    let saved = sqlx::query!("SELECT email, name FROM subscriptions",)
+        .fetch_one(&mut connection)
+        .await
+        .expect("Failed to fetch saved subscription.");
+
+    assert_eq!(saved.email, "[email protected]");
+    assert_eq!(saved.name, "le guin");
 }
 
 #[tokio::test]