diff --git a/src/testRunner/runner.ts b/src/testRunner/runner.ts
index 05e3f4aea1e70..f84e6df70b7ac 100644
--- a/src/testRunner/runner.ts
+++ b/src/testRunner/runner.ts
@@ -280,6 +280,9 @@ function beginTests() {
 
 export let isWorker: boolean;
 function startTestEnvironment() {
+    // For debugging convenience.
+    (globalThis as any).ts = ts;
+
     isWorker = handleTestConfig();
     if (isWorker) {
         return Parallel.Worker.start();