implement test changes regarding database

also added .env for database connection details (used by sqlx)

.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> {
     // Try convert into Settings type
     settings.try_into()
 }
+
+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

@@ -1,6 +1,9 @@
 use std::net::TcpListener;
 use mail_app::startup::run;
 
+use sqlx::{PgConnection, Connection};
+use mail_app::configuration::get_configuration;
+
 // Create new instance of the application on a random port and return address [`http://localhost:XXXX`]
 fn spawn_app() -> String {
     let listener = TcpListener::bind("127.0.0.1:0").expect("Failed to bind to random port");
@@ -36,6 +39,12 @@ async fn health_check_works() {
 async fn subscribe_returns_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();
+    // Connection trait MUST be in scope to invoke.
+    let mut connection = PgConnection::connect(&connection_string)
+        .await
+        .expect("Failed to connect to Postgres.");
     let client = reqwest::Client::new();
     let body = "name=le%20guin&email=usrula_le_guin%40gmail.com";
 
@@ -50,6 +59,14 @@ async fn subscribe_returns_200_for_valid_form_data() {
 
     // Assert test
     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, "ursula_le_guin@gmail.com");
+    assert_eq!(saved.name, "le guin");
 }
 
 #[actix_rt::test]