Create handler test file and test promise cases (#346)

* Create handler test file and test promise cases

* Change XO rule of ava importing as test and add rewire and sinon as dependencies

* Complete 100% of coverage reports

* Add fixtures for handler tests

* Remove package-lock to resolve git conflicts

package.json

@@ -18,6 +18,7 @@
     ],
     "extends": "prettier",
     "rules": {
+      "ava/use-test": 0,
       "unicorn/no-process-exit": 0
     }
   },
@@ -51,6 +52,8 @@
     "request": "2.83.0",
     "request-promise": "4.2.2",
     "resumer": "0.0.0",
+    "rewire": "3.0.2",
+    "sinon": "4.4.3",
     "test-listen": "1.0.2",
     "then-sleep": "1.0.1",
     "xo": "0.18.2"

test/fixtures/babel-promise-export.js

@@ -0,0 +1 @@
+module.exports = { default: (async () => () => 'test')() }

test/fixtures/native-promise-export.js

@@ -0,0 +1 @@
+module.exports = (async () => () => 'test')()

test/fixtures/regular-object.js

@@ -0,0 +1 @@
+module.exports = {}

test/fixtures/syntax-error.js

@@ -0,0 +1 @@
+throw new SyntaxError('async')

test/handler.js

@@ -0,0 +1,62 @@
+// Native
+const path = require('path')
+
+// Packages
+const { serial: test } = require('ava')
+const sinon = require('sinon')
+const rewire = require('rewire')
+
+const handle = rewire('../lib/handler')
+
+test.beforeEach(() => {
+  sinon.stub(process, 'exit')
+  process.exit.callsFake(() => {
+    // Throw error to finish the execution of the code
+    throw new Error()
+  })
+})
+
+test.afterEach(() => {
+  process.exit.restore()
+  try {
+    String.prototype.split.restore()
+  } catch (err) {}
+})
+
+test('handle a PromiseInstance', async t => {
+  const file = path.resolve('test/fixtures/native-promise-export')
+  const result = await handle(file)
+  t.is(typeof result, 'function')
+})
+
+test('handle an object that holds a PromiseInstance', async t => {
+  const file = path.resolve('test/fixtures/babel-promise-export')
+  const result = await handle(file)
+  t.is(typeof result, 'function')
+})
+
+test('process.exit when handling an invalid object', async t => {
+  const file = path.resolve('test/fixtures/regular-object')
+  const promise = handle(file)
+  await t.throws(promise)
+  t.is(process.exit.getCall(0).args[0], 1)
+})
+
+test('process.exit when handling and inexisting file', async t => {
+  const file = path.resolve('foo/bar')
+  const promise = handle(file)
+  await t.throws(promise)
+  t.is(process.exit.getCall(0).args[0], 1)
+})
+
+test('log and process.exit when node version is below 8', async t => {
+  // Stub process.versions.node.split()
+  sinon.stub(String.prototype, 'split').callsFake(() => '7')
+  const logErrorSpy = sinon.spy()
+  handle.__set__('logError', logErrorSpy)
+  const file = path.resolve('test/fixtures/syntax-error')
+  const promise = handle(file)
+  await t.throws(promise)
+  t.is(logErrorSpy.callCount, 2)
+  t.is(process.exit.getCall(0).args[0], 1)
+})