add a guard to the task callback drainschedule-drain

2 files changed, 6 insertions, 4 deletions

diff --git a/lib/internal/queue.js b/lib/internal/queue.js
index fdbabbc..fffea99 100644
--- a/lib/internal/queue.js
+++ b/lib/internal/queue.js
@@ -115,8 +115,10 @@ export default function queue(worker, concurrency, payload) {
                 trigger('unsaturated')
             }
 
-            if (q.idle()) {
+            if (q.idle() && !drainScheduled) {
+                drainScheduled = true
                 trigger('drain')
+                drainScheduled = false
             }
             q.process();
         };
diff --git a/test/queue.js b/test/queue.js
index bd71b05..c99380e 100644
--- a/test/queue.js
+++ b/test/queue.js
@@ -690,8 +690,8 @@ describe('queue', function(){
     });
 
     it('should not schedule another drain call if one is running', (done) => {
-        const q = async.queue(() => {
-            throw new Error('should not be called')
+        const q = async.queue((task, cb) => {
+            cb(null, task);
         })
 
         let numCalled = 0
@@ -702,7 +702,7 @@ describe('queue', function(){
             numCalled++
             q.push([])
         })
-        q.push([])
+        q.push('foo')
 
         setTimeout(() => {
             expect(numCalled).to.equal(1)