fix: clean up setTimeout timers in MockEventSource to prevent test hangs

The MockEventSource was creating setTimeout calls that weren't being cleaned up.
These orphaned timers kept the Node.js event loop alive, causing the test suite
to hang with a 30+ second timeout. Now we track all timeout IDs and clear them
in the close() method to ensure proper cleanup.

Author: eablack

test/unit/lib/run/log-displayer.unit.test.ts

@@ -36,6 +36,7 @@ describe('logDisplayer', function () {
       public readyState: number = 0 // CONNECTING
       public url: string
       private errorCode: number
+      private timeouts: NodeJS.Timeout[] = []
 
       constructor(url: string, options?: any) {
         this.url = url
@@ -48,7 +49,7 @@ describe('logDisplayer', function () {
         }
 
         // Simulate connection attempt
-        setTimeout(() => {
+        const timeout1 = setTimeout(() => {
           // Check if this is the test that expects success (specific URL pattern for non-tail mode)
           const isSuccessTest = this.url.includes('logs.heroku.com') && this.url.includes('tail=false')
 
@@ -74,7 +75,7 @@ describe('logDisplayer', function () {
             }
 
             // Close after sending messages
-            setTimeout(() => {
+            const timeout2 = setTimeout(() => {
               this.close()
               // For non-tail mode, trigger error event to resolve the promise
               if (this.onerror) {
@@ -85,6 +86,7 @@ describe('logDisplayer', function () {
                 this.onerror(closeEvent)
               }
             }, 20)
+            this.timeouts.push(timeout2)
           } else if (this.onerror) {
             // Create a mock error event with status code
             const errorEvent = {
@@ -94,6 +96,7 @@ describe('logDisplayer', function () {
             this.onerror(errorEvent)
           }
         }, 10)
+        this.timeouts.push(timeout1)
       }
 
       addEventListener(type: string, listener: (event: any) => void) {
@@ -117,6 +120,11 @@ describe('logDisplayer', function () {
 
       close() {
         this.readyState = 2 // CLOSED
+        // Clear all pending timeouts to prevent them from running after tests complete
+        for (const timeout of this.timeouts) {
+          clearTimeout(timeout)
+        }
+        this.timeouts = []
       }
     }
 
@@ -132,6 +140,10 @@ describe('logDisplayer', function () {
     if (createEventSourceStub) {
       createEventSourceStub.restore()
     }
+    // Ensure displayer is cleaned up to avoid hanging
+    if (displayer) {
+      displayer = null as any
+    }
   })
 
   after(function () {