test: add integration tests and test dependencies

Cargo.toml

@@ -40,6 +40,7 @@ axum-otel = { path = "crates/axum-otel", version = "0.31.5" }
 config = { version = "0.14.0", default-features = false }
 dotenvy = { version = "0.15.7" }
 http = { version = "1.3.1" }
+http-body-util = { version = "0.1" }
 opentelemetry = { version = "0.31.0", default-features = false }
 opentelemetry-appender-tracing = { version = "0.31.0" }
 opentelemetry-http = { version = "0.31.0", default-features = false }

crates/axum-otel/Cargo.toml

@@ -17,3 +17,12 @@ opentelemetry = { workspace = true }
 tower-http = { workspace = true }
 tracing = { workspace = true }
 tracing-otel-extra = { workspace = true, features = ["macros"] }
+
+[dev-dependencies]
+http-body-util = { workspace = true }
+opentelemetry_sdk = { workspace = true, features = ["testing"] }
+reqwest = { workspace = true }
+tokio = { workspace = true }
+tower = { workspace = true }
+tracing-opentelemetry = { workspace = true }
+tracing-subscriber = { workspace = true, features = ["registry"] }

crates/axum-otel/tests/integration.rs

@@ -0,0 +1,125 @@
+use axum::{
+    Router,
+    body::Body,
+    http::{Method, Request, StatusCode},
+    routing::get,
+};
+use axum_otel::{AxumOtelOnFailure, AxumOtelOnResponse, AxumOtelSpanCreator, Level};
+use http_body_util::BodyExt;
+use opentelemetry::{global, trace::TracerProvider};
+use opentelemetry_sdk::{
+    Resource,
+    trace::{InMemorySpanExporter, RandomIdGenerator, Sampler, SdkTracerProvider},
+};
+use tower::ServiceExt;
+use tower_http::trace::TraceLayer;
+use tracing::instrument;
+use tracing_subscriber::{Registry, layer::SubscriberExt, util::SubscriberInitExt};
+
+#[instrument]
+async fn hello() -> &'static str {
+    "Hello, world!"
+}
+
+fn app() -> Router<()> {
+    Router::new().route("/", get(hello)).layer(
+        TraceLayer::new_for_http()
+            .make_span_with(AxumOtelSpanCreator::new().level(Level::INFO))
+            .on_response(AxumOtelOnResponse::new().level(Level::INFO))
+            .on_failure(AxumOtelOnFailure::new()),
+    )
+}
+
+#[tokio::test]
+async fn test_axum_otel_middleware() {
+    // Set up in-memory exporter for testing
+    let exporter = InMemorySpanExporter::default();
+    let provider: SdkTracerProvider = SdkTracerProvider::builder()
+        .with_sampler(Sampler::AlwaysOn)
+        .with_id_generator(RandomIdGenerator::default())
+        .with_simple_exporter(exporter.clone())
+        .with_resource(Resource::builder().build())
+        .build();
+
+    global::set_tracer_provider(provider.clone());
+
+    // Set up tracing subscriber with OpenTelemetry layer
+    let tracer = provider.tracer("axum-otel-test".to_string());
+    let otel_layer = tracing_opentelemetry::OpenTelemetryLayer::new(tracer);
+    Registry::default()
+        .with(otel_layer)
+        .try_init()
+        .expect("Failed to initialize tracing subscriber");
+
+    let app = app();
+
+    // Send request using oneshot
+    let response = app
+        .oneshot(
+            Request::builder()
+                .uri("/")
+                .method(Method::GET)
+                .body(Body::empty())
+                .expect("Failed to build request"),
+        )
+        .await
+        .expect("Failed to send request");
+
+    assert_eq!(response.status(), StatusCode::OK);
+
+    let body = response
+        .into_body()
+        .collect()
+        .await
+        .expect("Failed to read body");
+
+    assert_eq!(body.to_bytes(), "Hello, world!".as_bytes());
+
+    // Force flush to ensure spans are exported
+    let _ = provider.force_flush();
+
+    // Verify spans were created
+    let spans = exporter
+        .get_finished_spans()
+        .expect("Failed to get finished spans");
+
+    assert!(
+        !spans.is_empty(),
+        "Expected at least one span to be created"
+    );
+
+    // With oneshot(), there's no MatchedPath, so span name is just "GET"
+    // When using a real server, it would be "GET /"
+    let request_span = spans
+        .iter()
+        .find(|s| s.name == "GET" || s.name == "GET /")
+        .expect("Request span not found");
+
+    let hello_span = spans
+        .iter()
+        .find(|s| s.name == "hello")
+        .expect("Handler span not found");
+
+    assert_eq!(
+        hello_span.parent_span_id,
+        request_span.span_context.span_id(),
+        "Handler span should be a child of the request span"
+    );
+
+    // Check http.status_code attribute
+    let status_code_attr = request_span
+        .attributes
+        .iter()
+        .find(|kv| kv.key.as_str() == "http.status_code")
+        .map(|kv| kv.value.to_string());
+
+    assert_eq!(
+        status_code_attr,
+        Some("200".to_string()),
+        "Expected http.status_code to be 200"
+    );
+
+    provider
+        .shutdown()
+        .expect("Failed to shutdown tracer provider");
+}

crates/tracing-opentelemetry/src/resource.rs

@@ -28,3 +28,35 @@ pub fn get_resource(service_name: &str, attributes: &[KeyValue]) -> Resource {
         .with_attributes(attributes.to_vec())
         .build()
 }
+
+#[cfg(test)]
+mod tests {
+    use super::get_resource;
+    use opentelemetry::KeyValue;
+
+    #[test]
+    fn test_get_resource() {
+        let service_name = "test-service";
+        let attributes = vec![
+            KeyValue::new("env", "test"),
+            KeyValue::new("version", "1.0.0"),
+        ];
+
+        let resource = get_resource(service_name, &attributes);
+
+        assert_eq!(
+            resource.get(&opentelemetry::Key::new("service.name")),
+            Some(opentelemetry::Value::String(service_name.into()))
+        );
+
+        assert_eq!(
+            resource.get(&opentelemetry::Key::new("env")),
+            Some(opentelemetry::Value::String("test".into()))
+        );
+
+        assert_eq!(
+            resource.get(&opentelemetry::Key::new("version")),
+            Some(opentelemetry::Value::String("1.0.0".into()))
+        );
+    }
+}