refactor(test): Use co-mocha for async tests

This improves error handling within tests so that they shouldn't time out when an assertion fails from within a callback. Server instances created within tests are also closed in finally blocks to avoid making Mocha hanging at the end.

This also greatly improves the performance of bulk generation of objects by allowing 100 concurrent uploads at a time. The indefinite timeout on these long-running tests has been removed.

lib/utils.js

@@ -90,3 +90,12 @@ exports.concatStreams = function(streams) {
   pipeNext(streams.shift());
   return passThrough;
 };
+
+exports.thunkToPromise = function(fn) {
+  return new Promise((resolve, reject) => {
+    fn((err, ...args) => {
+      if (err) return reject(err);
+      resolve(args.length > 1 ? args : args[0]);
+    });
+  });
+};

package.json

@@ -4,7 +4,7 @@
   "description": "Fake S3 server for node",
   "main": "lib/index.js",
   "scripts": {
-    "test": "mocha --timeout 30000 --reporter spec --ui bdd",
+    "test": "mocha --require co-mocha --timeout 30000 --reporter spec --ui bdd",
     "prettier-check": "prettier-check --ignore-path .gitignore \"**/*.js\"",
     "prettier-fix": "prettier --ignore-path .gitignore --write \"**/*.js\"",
     "eslint": "eslint --ignore-path .gitignore \"**/*.js\"",
@@ -36,6 +36,7 @@
     "jstoxml": "^1.0.0",
     "lodash": "^4.0.0",
     "morgan": "^1.5.1",
+    "promise-limit": "^2.6.0",
     "rxjs": "^5.4.0",
     "winston": "^2.1.0",
     "xml2js": "^0.4.4",
@@ -44,14 +45,17 @@
   "devDependencies": {
     "aws-sdk": "2.208.0",
     "chai": "4.1.2",
+    "chai-as-promised": "7.1.1",
+    "co-mocha": "1.2.2",
     "eslint": "4.18.2",
     "eslint-config-prettier": "2.9.0",
     "md5": "2.2.1",
     "mocha": "5.0.4",
     "moment": "2.21.0",
     "prettier": "1.11.1",
     "prettier-check": "2.0.0",
-    "request": "2.85.0"
+    "request": "2.85.0",
+    "request-promise-native": "1.0.5"
   },
   "engines": {
     "node": ">=6.0.0"