[o11y] Refactor sql-test-tail.js

This test was poorly designed and failed to await promises for the test output
properly, doing so means we receive one additional span by the time we check the
test output. The test now follows the regular test STW more closely and is much
easier to understand.

Author: fhanau

src/workerd/api/sql-test-tail.js

@@ -4,10 +4,8 @@ let invocationPromises = [];
 let spans = new Map();
 
 export default {
-  async fetch(ctrl, env, ctx) {
-    return new Response('');
-  },
   async test(ctrl, env, ctx) {
+    await Promise.allSettled(invocationPromises);
     let received = Array.from(spans.values()).filter(
       (span) => span.name !== 'jsRpcSession'
     );
@@ -17,15 +15,14 @@ export default {
       acc[curr.name]++;
       return acc;
     }, {});
-    await Promise.allSettled(invocationPromises);
     assert.deepStrictEqual(reduced, {
       durable_object_storage_exec: 268,
       durable_object_storage_ingest: 1031,
       durable_object_storage_getDatabaseSize: 3,
       durable_object_storage_put: 18,
       durable_object_storage_get: 18,
       durable_object_storage_transaction: 8,
-      durable_object_subrequest: 46,
+      durable_object_subrequest: 47,
       durable_object_storage_deleteAll: 1,
       createStringTable: 4,
       runActorFunc: 4,
@@ -48,34 +45,37 @@ export default {
         resolveFn = resolve;
       })
     );
+    const topLevelSpanId = event.event.spanId;
 
     return (event) => {
       try {
-        const rpcMethodName = Array.isArray(event.event.info)
-          ? (event.event.info || []).find(
-              (item) => item['name'] === 'jsrpc.method'
-            )?.value
-          : undefined;
-        const spanUniqueId = `${event.spanContext.traceId}#${event.event.spanId || event.spanContext.spanId}`;
+        let spanKey =
+          event.invocationId + (event.event.spanId || event.spanContext.spanId);
         switch (event.event.type) {
           case 'spanOpen':
             // The span ids will change between tests, but Map preserves insertion order
-            spans.set(spanUniqueId, {
-              name: event.event.name || rpcMethodName,
+            spans.set(spanKey, {
+              name: event.event.name,
             });
             break;
           case 'attributes': {
-            let span = spans.get(spanUniqueId) || { name: rpcMethodName };
+            let span = spans.get(spanKey);
+            if (event.spanContext.spanId == topLevelSpanId) {
+              // top-level JsRpc method name attribute – transform into a span with the given name
+              const rpcMethodName = event.event.info.find(
+                (item) => item['name'] === 'jsrpc.method'
+              ).value;
+              span = { name: rpcMethodName };
+            }
             for (let { name, value } of event.event.info) {
               span[name] = value;
             }
-            spans.set(spanUniqueId, span);
+            spans.set(spanKey, span);
             break;
           }
           case 'spanClose': {
-            let span = spans.get(spanUniqueId);
+            let span = spans.get(spanKey);
             span['closed'] = true;
-            spans.set(spanUniqueId, span);
             break;
           }
           case 'outcome':