Feature/556/better timeout error messages (#557)

* (#556) Store intermediate results and errors to provide additional context on timeout

* (#556) Update testcases

Author: s1hofmann

lib/util/timeout.function.spec.ts

@@ -16,7 +16,9 @@ describe("timeout", () => {
     try {
       await timeout(updateInterval, maxDuration, action);
     } catch (e) {
-      expect(e).toBe(`Action timed out after ${maxDuration} ms`);
+      expect(e).toBe(
+        `Action timed out after ${maxDuration} ms. Last rejection reason was: false.`,
+      );
     }
     const end = Date.now();
 
@@ -37,7 +39,9 @@ describe("timeout", () => {
     try {
       await timeout(updateInterval, maxDuration, action);
     } catch (e) {
-      expect(e).toEqual(`Action timed out after ${maxDuration} ms`);
+      expect(e).toEqual(
+        `Action timed out after ${maxDuration} ms. Didn't receive a result within timeout.`,
+      );
     }
     const end = Date.now();
 
@@ -90,7 +94,7 @@ describe("timeout", () => {
     const action = jest.fn(() => {
       const interval = Date.now() - start;
       return new Promise<boolean>((resolve, reject) =>
-        interval > delay ? resolve(true) : reject()
+        interval > delay ? resolve(true) : reject(),
       );
     });
 
@@ -114,7 +118,9 @@ describe("timeout", () => {
     try {
       await timeout(updateInterval, maxDuration, action);
     } catch (e) {
-      expect(e).toEqual(`Action timed out after ${maxDuration} ms`);
+      expect(e).toEqual(
+        `Action timed out after ${maxDuration} ms. Didn't receive a result within timeout.`,
+      );
     }
     const end = Date.now();
 
@@ -137,7 +143,9 @@ describe("timeout", () => {
     const SUT = () => timeout(updateInterval, maxDuration, action);
 
     // THEN
-    await expect(SUT).rejects.toBe(`Action timed out after ${maxDuration} ms`);
+    await expect(SUT).rejects.toBe(
+      `Action timed out after ${maxDuration} ms. Didn't receive a result within timeout.`,
+    );
     expect(action).toBeCalledTimes(1);
   });
 
@@ -157,7 +165,9 @@ describe("timeout", () => {
     const SUT = () => timeout(updateInterval, maxDuration, action);
 
     // THEN
-    await expect(SUT).rejects.toBe(`Action timed out after ${maxDuration} ms`);
+    await expect(SUT).rejects.toBe(
+      `Action timed out after ${maxDuration} ms. Didn't receive a result within timeout.`,
+    );
     expect(action).toBeCalledTimes(1);
     await sleep(500);
     expect(action).toBeCalledTimes(1);

lib/util/timeout.function.ts

@@ -8,11 +8,13 @@ export function timeout<R>(
   updateIntervalMs: number,
   maxDurationMs: number,
   action: (...params: any) => Promise<R>,
-  config?: TimoutConfig
+  config?: TimoutConfig,
 ): Promise<R> {
   return new Promise<R>((resolve, reject) => {
     let interval: NodeJS.Timeout;
     let timerCleaned = false;
+    let lastResult: R | null;
+    let lastRejectionReason: any | null;
 
     if (config?.signal) {
       config.signal.onabort = () => {
@@ -29,12 +31,16 @@ export function timeout<R>(
       if (!result && !timerCleaned) {
         interval = setTimeout(executeInterval, updateIntervalMs);
       } else {
+        lastResult = result;
+        lastRejectionReason = null;
         cleanupTimer();
         resolve(result);
       }
     }
 
-    function handleRejection() {
+    function handleRejection(reason: any) {
+      lastRejectionReason = reason;
+      lastResult = null;
       if (!timerCleaned) {
         interval = setTimeout(executeInterval, updateIntervalMs);
       }
@@ -52,7 +58,17 @@ export function timeout<R>(
 
     const maxTimeout = setTimeout(() => {
       cleanupTimer();
-      reject(`Action timed out after ${maxDurationMs} ms`);
+      let additionalInformation: string | undefined;
+      if (lastResult == null && lastRejectionReason != null) {
+        additionalInformation = `Last rejection reason was: ${lastRejectionReason}.`;
+      } else if (lastResult == null && lastRejectionReason == null) {
+        additionalInformation = `Didn't receive a result within timeout.`;
+      }
+      reject(
+        `Action timed out after ${maxDurationMs} ms.${
+          additionalInformation ? ` ${additionalInformation}` : ""
+        }`,
+      );
     }, maxDurationMs);
 
     executeInterval();