From f10752bff96c0bc428f74ed8f105b68c784f6bd1 Mon Sep 17 00:00:00 2001
From: Gidi Meir Morris <github@gidi.io>
Date: Thu, 23 Jul 2020 12:20:14 +0100
Subject: [PATCH] simplified buffer tests to reduce flakyness

---
 .../server/lib/bulk_operation_buffer.test.ts  | 80 ++++++++-----------
 1 file changed, 32 insertions(+), 48 deletions(-)

diff --git a/x-pack/plugins/task_manager/server/lib/bulk_operation_buffer.test.ts b/x-pack/plugins/task_manager/server/lib/bulk_operation_buffer.test.ts
index 3a21f622cec17..f32a755515a95 100644
--- a/x-pack/plugins/task_manager/server/lib/bulk_operation_buffer.test.ts
+++ b/x-pack/plugins/task_manager/server/lib/bulk_operation_buffer.test.ts
@@ -33,8 +33,7 @@ function errorAttempts(task: TaskInstance): Err<OperationError<TaskInstance, Err
   });
 }
 
-// FLAKY: https://github.com/elastic/kibana/issues/72864
-describe.skip('Bulk Operation Buffer', () => {
+describe('Bulk Operation Buffer', () => {
   describe('createBuffer()', () => {
     test('batches up multiple Operation calls', async () => {
       const bulkUpdate: jest.Mocked<BulkOperation<TaskInstance, Error>> = jest.fn(
@@ -67,8 +66,6 @@ describe.skip('Bulk Operation Buffer', () => {
       const task2 = createTask();
       const task3 = createTask();
       const task4 = createTask();
-      const task5 = createTask();
-      const task6 = createTask();
 
       return new Promise((resolve) => {
         Promise.all([bufferedUpdate(task1), bufferedUpdate(task2)]).then((_) => {
@@ -79,22 +76,18 @@ describe.skip('Bulk Operation Buffer', () => {
 
         setTimeout(() => {
           // on next tick
-          setTimeout(() => {
-            // on next tick
-            expect(bulkUpdate).toHaveBeenCalledTimes(2);
-            Promise.all([bufferedUpdate(task5), bufferedUpdate(task6)]).then((_) => {
-              expect(bulkUpdate).toHaveBeenCalledTimes(3);
-              expect(bulkUpdate).toHaveBeenCalledWith([task5, task6]);
-              resolve();
-            });
-          }, bufferMaxDuration + 1);
-
           expect(bulkUpdate).toHaveBeenCalledTimes(1);
           Promise.all([bufferedUpdate(task3), bufferedUpdate(task4)]).then((_) => {
             expect(bulkUpdate).toHaveBeenCalledTimes(2);
             expect(bulkUpdate).toHaveBeenCalledWith([task3, task4]);
           });
-        }, bufferMaxDuration + 1);
+
+          setTimeout(() => {
+            // on next tick
+            expect(bulkUpdate).toHaveBeenCalledTimes(2);
+            resolve();
+          }, bufferMaxDuration * 1.1);
+        }, bufferMaxDuration * 1.1);
       });
     });
 
@@ -103,8 +96,9 @@ describe.skip('Bulk Operation Buffer', () => {
         return Promise.resolve(tasks.map(incrementAttempts));
       });
 
+      const bufferMaxDuration = 1000;
       const bufferedUpdate = createBuffer(bulkUpdate, {
-        bufferMaxDuration: 100,
+        bufferMaxDuration,
         bufferMaxOperations: 2,
       });
 
@@ -114,26 +108,19 @@ describe.skip('Bulk Operation Buffer', () => {
       const task4 = createTask();
       const task5 = createTask();
 
-      return new Promise((resolve) => {
-        bufferedUpdate(task1);
-        bufferedUpdate(task2);
-        bufferedUpdate(task3);
-        bufferedUpdate(task4);
-
-        setTimeout(() => {
-          expect(bulkUpdate).toHaveBeenCalledTimes(2);
-          expect(bulkUpdate).toHaveBeenCalledWith([task1, task2]);
-          expect(bulkUpdate).toHaveBeenCalledWith([task3, task4]);
-
-          setTimeout(() => {
-            expect(bulkUpdate).toHaveBeenCalledTimes(2);
-            bufferedUpdate(task5).then((_) => {
-              expect(bulkUpdate).toHaveBeenCalledTimes(3);
-              expect(bulkUpdate).toHaveBeenCalledWith([task5]);
-              resolve();
-            });
-          }, 50);
-        }, 50);
+      return Promise.all([
+        bufferedUpdate(task1),
+        bufferedUpdate(task2),
+        bufferedUpdate(task3),
+        bufferedUpdate(task4),
+      ]).then(() => {
+        expect(bulkUpdate).toHaveBeenCalledTimes(2);
+        expect(bulkUpdate).toHaveBeenCalledWith([task1, task2]);
+        expect(bulkUpdate).toHaveBeenCalledWith([task3, task4]);
+        return bufferedUpdate(task5).then((_) => {
+          expect(bulkUpdate).toHaveBeenCalledTimes(3);
+          expect(bulkUpdate).toHaveBeenCalledWith([task5]);
+        });
       });
     });
 
@@ -153,29 +140,26 @@ describe.skip('Bulk Operation Buffer', () => {
       const task3 = createTask();
       const task4 = createTask();
 
-      return new Promise((resolve) => {
-        bufferedUpdate(task1);
-        bufferedUpdate(task2);
-
-        setTimeout(() => {
-          expect(bulkUpdate).toHaveBeenCalledTimes(1);
-          expect(bulkUpdate).toHaveBeenCalledWith([task1, task2]);
+      return Promise.all([bufferedUpdate(task1), bufferedUpdate(task2)]).then(() => {
+        expect(bulkUpdate).toHaveBeenCalledTimes(1);
+        expect(bulkUpdate).toHaveBeenCalledWith([task1, task2]);
 
-          bufferedUpdate(task3);
-          bufferedUpdate(task4);
+        return new Promise((resolve) => {
+          const futureUpdates = Promise.all([bufferedUpdate(task3), bufferedUpdate(task4)]);
 
           setTimeout(() => {
             expect(bulkUpdate).toHaveBeenCalledTimes(1);
 
-            setTimeout(() => {
+            futureUpdates.then(() => {
               expect(bulkUpdate).toHaveBeenCalledTimes(2);
               expect(bulkUpdate).toHaveBeenCalledWith([task3, task4]);
               resolve();
-            }, bufferMaxDuration / 2);
+            });
           }, bufferMaxDuration / 2);
-        }, bufferMaxDuration + 1);
+        });
       });
     });
+
     test('handles both resolutions and rejections at individual task level', async (done) => {
       const bulkUpdate: jest.Mocked<BulkOperation<TaskInstance, Error>> = jest.fn(
         ([task1, task2, task3]) => {