fix: empty input empty output

.travis.yml

@@ -3,8 +3,10 @@ language: node_js
 node_js:
   - '8'
   - '10'
+before_install:
+  - npm i npminstall -g
 install:
-  - npm i npminstall && npminstall
+  - npminstall
 script:
   - npm run ci
 after_script:

index.js

@@ -9,18 +9,24 @@ module.exports = function (funcs, n) {
   if (funcs.some(func => func && typeof func.then === 'function')) n = funcs.length;
 
   return new Promise(resolve => {
+    if (funcs.length === 0) return resolve([]);
+
     const results = [];
     let index = 0;
     let finish = 0;
-
     for (let i = 0; i < n; i++) {
       run();
     }
 
     function run() {
       const i = index++;
+      if (i >= funcs.length) return;
       let ins = funcs[i];
-      if (!ins) return;
+      if (!ins) {
+        results[i] = undefined;
+        if (++finish >= funcs.length) return resolve(results);
+        return;
+      }
 
       if (typeof ins === 'function') ins = ins();
       if (ins && typeof ins.next === 'function' && typeof ins.throw === 'function') ins = require('co')(ins);

test/index.test.js

@@ -113,6 +113,16 @@ describe('co-gather', () => {
     // notice: promise will start at once
     around(use, 300);
   });
+
+  it('should work with empty array', async () => {
+    const res = await gather([]);
+    assert.deepEqual(res, []);
+  });
+
+  it('should work with undefined item', async () => {
+    const res = await gather([ undefined, afun(3, null, 200) ]);
+    assert.deepEqual(res, [ undefined, { value: 3, isError: false } ]);
+  });
 });
 
 function around(a, b) {