feat(test): log for integration tests

- log for test are configurable to either be spit into the void (cargo
test default) or into `stdout`.

src/main.rs

@@ -8,7 +8,11 @@ use sqlx::PgPool;
 async fn main() -> Result<(), std::io::Error> {
     let configuration = get_configuration().expect("Failed to read configuration");
 
-    let subscriber = get_subscriber("email_newsletter_api".into(), "info".into());
+    let subscriber = get_subscriber(
+        "email_newsletter_api".into(),
+        "info".into(),
+        std::io::stdout,
+    );
     init_subscriber(subscriber);
 
     let db_conn = PgPool::connect(&configuration.database.connection_string())

src/telemetry.rs

@@ -2,12 +2,19 @@ use tracing::subscriber::set_global_default;
 use tracing::Subscriber;
 use tracing_bunyan_formatter::{BunyanFormattingLayer, JsonStorageLayer};
 use tracing_log::LogTracer;
-use tracing_subscriber::{layer::SubscriberExt, EnvFilter, Registry};
+use tracing_subscriber::{fmt::MakeWriter, layer::SubscriberExt, EnvFilter, Registry};
 
-pub fn get_subscriber(name: String, env_filter: String) -> impl Subscriber + Send + Sync {
+pub fn get_subscriber<Sink>(
+    name: String,
+    env_filter: String,
+    sink: Sink,
+) -> impl Subscriber + Send + Sync
+where
+    Sink: for<'a> MakeWriter<'a> + Send + Sync + 'static,
+{
     let env_filter =
         EnvFilter::try_from_default_env().unwrap_or_else(|_| EnvFilter::new(env_filter));
-    let formatting_layer = BunyanFormattingLayer::new(name, std::io::stdout);
+    let formatting_layer = BunyanFormattingLayer::new(name, sink);
     Registry::default()
         .with(env_filter)
         .with(JsonStorageLayer)
@@ -15,6 +22,9 @@ pub fn get_subscriber(name: String, env_filter: String) -> impl Subscriber + Sen
 }
 
 // init_subscriber should only be called once
+//
+// This is solved with the once_cell crate
+// until the std::sync::SyncOnceCell is stable in the toolchain
 pub fn init_subscriber(subscriber: impl Subscriber + Send + Sync) {
     LogTracer::init().expect("Failed to set logger");
     set_global_default(subscriber).expect("Failed to set subscriber");