Handle non-zero exit from commands run in a way needed by execa

Fixes #197

lib/utils/run.js

@@ -17,9 +17,8 @@ module.exports = function run(command, args, opts) {
 
   debug('spawned with execa.shell', cmdArgs, opts);
 
-  return child.then((child) => {
-    if (child.code !== 0) {
-      return Promise.reject(child.code);
-    }
+  return child.catch((error) => {
+    debug('error', error);
+    return Promise.reject(error.code);
   });
 };

test/utils/run-test.js

@@ -0,0 +1,15 @@
+'use strict';
+
+const expect = require('chai').expect;
+
+describe('utils/run', () => {
+  it('rejects if command exits non-zero', () => {
+    let run = require('../../lib/utils/run');
+
+    return run('exit 1', [], {}).then(() => {
+      expect(true).to.equal(false, 'Should not succeed');
+    }).catch((res) => {
+      expect(res).to.equal(1, 'Should reject with exit code');
+    });
+  });
+});