fix(dataset): avoid to call the source when upadte is canceled

src/autocomplete/dataset.js

@@ -207,7 +207,13 @@ _.mixin(Dataset.prototype, EventEmitter, {
       handleSuggestions.apply(this, [this.cachedSuggestions].concat(this.cachedRenderExtraArgs));
     } else {
       var that = this;
-      var execSource = function() { that.source(query, handleSuggestions.bind(that)); };
+      var execSource = function() {
+        // When the call is debounced the condition avoid to do a useless
+        // request with the last character when the input has been cleared
+        if (!that.canceled) {
+          that.source(query, handleSuggestions.bind(that));
+        }
+      };
 
       if (this.debounce) {
         var later = function() {

test/unit/dataset_spec.js

@@ -364,6 +364,31 @@ describe('Dataset', function() {
         done();
       }, 500);
     });
+
+    it('should not call the source if update was canceled', function(done) {
+      var that = this;
+
+      this.dataset = new Dataset({
+        source: this.source,
+        debounce: 250
+      });
+
+      this.source.and.callFake(fakeGetWithSyncResultsAndExtraParams);
+
+      this.dataset.update('woah');
+      expect(this.source.calls.count()).toBe(0);
+
+      this.dataset.update('woah 2');
+      expect(this.source.calls.count()).toBe(0);
+
+      this.dataset.clear();
+      expect(this.source.calls.count()).toBe(0);
+
+      setTimeout(function() {
+        expect(that.source.calls.count()).toBe(0);
+        done();
+      }, 500);
+    });
   });
 
   describe('#cacheSuggestions', function() {