Add basic test for tracing layer (#703)

Author: DoumanAsh

sentry-tracing/tests/tracing.rs

@@ -0,0 +1,76 @@
+use sentry::{ClientOptions, Hub};
+use sentry_core::test::TestTransport;
+
+use std::sync::Arc;
+
+fn init_sentry() -> Arc<TestTransport> {
+    use tracing_subscriber::prelude::*;
+
+    let transport = TestTransport::new();
+    let options = ClientOptions {
+        dsn: Some("https://test@sentry-tracing.com/test".parse().unwrap()),
+        transport: Some(Arc::new(transport.clone())),
+        sample_rate: 1.0,
+        traces_sample_rate: 1.0,
+        ..ClientOptions::default()
+    };
+    Hub::current().bind_client(Some(Arc::new(options.into())));
+
+    let _ = tracing_subscriber::registry()
+        .with(sentry_tracing::layer().enable_span_attributes())
+        .try_init();
+
+    transport
+}
+
+#[tracing::instrument(fields(tags.tag = "key", not_tag = "value"))]
+fn function_with_tags(value: i32) {
+    tracing::error!(value, "event");
+}
+
+#[test]
+fn should_instrument_function_with_event() {
+    let transport = init_sentry();
+
+    function_with_tags(1);
+
+    let data = transport.fetch_and_clear_envelopes();
+    assert_eq!(data.len(), 2);
+    let event = data.first().expect("should have 1 event");
+    let event = match event.items().next().unwrap() {
+        sentry::protocol::EnvelopeItem::Event(event) => event,
+        unexpected => panic!("Expected event, but got {:#?}", unexpected),
+    };
+
+    //Validate transaction is created
+    let trace = match event.contexts.get("trace").expect("to get 'trace' context") {
+        sentry::protocol::Context::Trace(trace) => trace,
+        unexpected => panic!("Expected trace context but got {:?}", unexpected),
+    };
+    assert_eq!(trace.op.as_deref().unwrap(), "function_with_tags");
+
+    //Confirm transaction values
+    let transaction = data.get(1).expect("should have 1 transaction");
+    let transaction = match transaction.items().next().unwrap() {
+        sentry::protocol::EnvelopeItem::Transaction(transaction) => transaction,
+        unexpected => panic!("Expected transaction, but got {:#?}", unexpected),
+    };
+    assert_eq!(transaction.tags.len(), 1);
+    assert_eq!(transaction.extra.len(), 2);
+
+    let tag = transaction
+        .tags
+        .get("tag")
+        .expect("to have tag with name 'tag'");
+    assert_eq!(tag, "key");
+    let not_tag = transaction
+        .extra
+        .get("not_tag")
+        .expect("to have extra with name 'not_tag'");
+    assert_eq!(not_tag, "value");
+    let value = transaction
+        .extra
+        .get("value")
+        .expect("to have extra with name 'value'");
+    assert_eq!(value, 1);
+}