cancelable waterfall

3 files changed, 49 insertions, 0 deletions

diff --git a/lib/waterfall.js b/lib/waterfall.js
index 3e71d2c..7f5c12e 100644
--- a/lib/waterfall.js
+++ b/lib/waterfall.js
@@ -75,6 +75,7 @@ export default  function(tasks, callback) {
     }
 
     function next(err/*, ...args*/) {
+        if (err === null) return // canceled
         if (err || taskIndex === tasks.length) {
             return callback.apply(null, arguments);
         }
diff --git a/test/parallel.js b/test/parallel.js
index 2b07822..e4af6f8 100644
--- a/test/parallel.js
+++ b/test/parallel.js
@@ -191,6 +191,32 @@ describe('parallel', function() {
         });
     });
 
+    it('parallel limit canceled', function(done) {
+        const call_order = []
+        async.parallelLimit([
+            function(callback){
+                call_order.push(1)
+                callback();
+            },
+            function(callback){
+                call_order.push(2)
+                callback(false);
+            },
+            function(callback){
+                call_order.push(3)
+                callback('error', 2);
+            }
+        ],
+        1,
+        function(err){
+            throw new Error('should not get here')
+        });
+        setTimeout(() => {
+            expect(call_order).to.eql([1, 2]);
+            done()
+        }, 25);
+    });
+
     it('parallel call in another context @nycinvalid @nodeonly', function(done) {
         var vm = require('vm');
         var sandbox = {
diff --git a/test/waterfall.js b/test/waterfall.js
index 78b11bb..901d59b 100644
--- a/test/waterfall.js
+++ b/test/waterfall.js
@@ -90,6 +90,28 @@ describe("waterfall", function () {
         });
     });
 
+
+    it('canceled', function(done){
+        const call_order = []
+        async.waterfall([
+            function(callback){
+                call_order.push(1)
+                callback(null);
+            },
+            function(callback){
+                call_order.push(2)
+                assert(false, 'next function should not be called');
+                callback();
+            }
+        ], function(err){
+            throw new Error('should not get here')
+        });
+        setTimeout(() => {
+            expect(call_order).to.eql([1])
+            done()
+        }, 10)
+    });
+
     it('multiple callback calls', function(){
         var arr = [
             function(callback){