fix: BackgroundTaskHelper should support recursively call (#90)

Author: killagu

core/background-task/src/BackgroundTaskHelper.ts

@@ -54,16 +54,20 @@ export class BackgroundTaskHelper implements EggObjectLifecycle {
     if (!this.backgroundTasks.length) return;
 
     const { promise: timeout, resolve } = this.sleep();
+    const backgroundTasks = this.backgroundTasks.slice();
 
     await Promise.race([
       // not block the pre destroy process too long
       timeout,
       // ensure all background task are done before destroy the context
-      Promise.all(this.backgroundTasks),
+      Promise.all(backgroundTasks),
     ]);
-
     // always resolve the sleep promise
     resolve();
+    if (this.backgroundTasks.length !== backgroundTasks.length) {
+      this.backgroundTasks = this.backgroundTasks.slice(backgroundTasks.length);
+      return this.doPreDestroy();
+    }
   }
 
   private sleep() {

core/background-task/test/BackgroundTaskHelper.test.ts

@@ -57,4 +57,21 @@ describe('test/BackgroundTaskHelper.test.ts', () => {
       await helper.doPreDestroy();
     });
   });
+
+  describe('recursive fn', () => {
+    it('should done', async () => {
+      let runDone = 0;
+      helper.run(async () => {
+        await sleep(10);
+        runDone++;
+        helper.run(async () => {
+          await sleep(10);
+          runDone++;
+        });
+      });
+
+      await helper.doPreDestroy();
+      assert(runDone === 2);
+    });
+  });
 });

plugin/tegg/test/app/extend/context.test.ts

@@ -63,5 +63,19 @@ describe('test/app/extend/context.test.ts', () => {
       });
       assert(backgroundIsDone);
     });
+
+    it('recursive runInBackground should work', async () => {
+      let backgroundIsDone = false;
+      await app.mockModuleContextScope(async ctx => {
+        ctx.runInBackground(async () => {
+          await sleep(100);
+          ctx.runInBackground(async () => {
+            await sleep(100);
+            backgroundIsDone = true;
+          });
+        });
+      });
+      assert(backgroundIsDone);
+    });
   });
 });