feat(jest-environment-puppeteer): support custom config

Closes #19

README.md

@@ -159,22 +159,22 @@ For this use case, `jest-environment-puppeteer` exposes two methods: `setup` and
 
 ```js
 // global-setup.js
-const { setup: setupPuppeteer } = require('jest-environment-puppeteer');
+const { setup: setupPuppeteer } = require('jest-environment-puppeteer')
 
 module.exports = async function globalSetup() {
-  await setupPuppeteer();
+  await setupPuppeteer()
   // Your global setup
-};
+}
 ```
 
 ```js
 // global-teardown.js
-const { teardown: teardownPuppeteer } = require('jest-environment-puppeteer');
+const { teardown: teardownPuppeteer } = require('jest-environment-puppeteer')
 
 module.exports = async function globalTeardown() {
   // Your global teardown
-  await teardownPuppeteer();
-};
+  await teardownPuppeteer()
+}
 ```
 
 Then assigning your js file paths to the [`globalSetup`](https://facebook.github.io/jest/docs/en/configuration.html#globalsetup-string) and [`globalTeardown`](https://facebook.github.io/jest/docs/en/configuration.html#globalteardown-string) property in your Jest configuration.
@@ -223,7 +223,7 @@ await expect(page).toMatch('A text in the page')
 
 ### `jest-puppeteer.config.js`
 
-You can specify a `jest-puppeteer.config.js` at the root of the project.
+You can specify a `jest-puppeteer.config.js` at the root of the project or define a custom path using `JEST_PUPPETEER_CONFIG` environment variable.
 
 * `launch` <[object]> [All Puppeteer launch options](https://github.com/GoogleChrome/puppeteer/blob/master/docs/api.md#puppeteerlaunchoptions) can be specified in `jest-puppeteer.config.js` at the root of the project. Since it is JavaScript, you can use all stuff you need, including environment.
 * `server` <[Object]> Server options

packages/jest-environment-puppeteer/README.md

@@ -62,9 +62,9 @@ it('should fill an input', async () => {
 
 ### `jest-puppeteer.config.js`
 
-You can specify a `jest-puppeteer.config.js` at the root of the project.
+You can specify a `jest-puppeteer.config.js` at the root of the project or define a custom path using `JEST_PUPPETEER_CONFIG` environment variable.
 
-* `launch` <[object]> [All Puppeteer launch options](https://github.com/GoogleChrome/puppeteer/blob/master/docs/api.md#puppeteerlaunchoptions) can be specified in `jest-puppeteer.config.js` at the root of the project. Since it is JavaScript, you can use all stuff you need, including environment.
+* `launch` <[object]> [All Puppeteer launch options](https://github.com/GoogleChrome/puppeteer/blob/master/docs/api.md#puppeteerlaunchoptions) can be specified in config. Since it is JavaScript, you can use all stuff you need, including environment.
 * `server` <[Object]> Server options
   * `command` <[string]> Command to start server
   * `port` <[number]> If specified, it will wait port to be listened

packages/jest-environment-puppeteer/src/readConfig.js

@@ -6,7 +6,6 @@ import { merge } from 'lodash'
 
 const exists = promisify(fs.exists)
 
-const CONFIG_PATH = path.join(cwd(), 'jest-puppeteer.config.js')
 const DEFAULT_CONFIG = {
   launch: {},
 }
@@ -20,10 +19,24 @@ async function readConfig() {
   const defaultConfig =
     process.env.CI === 'true' ? DEFAULT_CONFIG_CI : DEFAULT_CONFIG
 
-  if (!await exists(CONFIG_PATH)) return defaultConfig
+  const hasCustomConfigPath = !!process.env.JEST_PUPPETEER_CONFIG
+  const configPath =
+    process.env.JEST_PUPPETEER_CONFIG || 'jest-puppeteer.config.js'
+  const absConfigPath = path.resolve(cwd(), configPath)
+  const configExists = await exists(absConfigPath)
+
+  if (hasCustomConfigPath && !configExists) {
+    throw new Error(
+      `Error: Can't find a root directory while resolving a config file path.\nProvided path to resolve: ${configPath}`,
+    )
+  }
+
+  if (!hasCustomConfigPath && !configExists) {
+    return defaultConfig
+  }
 
   // eslint-disable-next-line global-require, import/no-dynamic-require
-  const localConfig = require(CONFIG_PATH)
+  const localConfig = require(absConfigPath)
   return merge({}, defaultConfig, localConfig)
 }
 

packages/jest-environment-puppeteer/tests/__fixtures__/customConfig.js

@@ -0,0 +1,5 @@
+module.exports = {
+  server: {
+    command: 'yarn babel-node src/server/main.js',
+  },
+}

packages/jest-environment-puppeteer/tests/readConfig.test.js

@@ -0,0 +1,61 @@
+import fs from 'fs'
+import path from 'path'
+import readConfig from '../src/readConfig'
+
+jest.mock('fs')
+
+function mockExists(value) {
+  fs.exists.mockImplementation((path, callback) => callback(null, value))
+}
+
+describe('readConfig', () => {
+  describe('with custom config path', () => {
+    beforeEach(() => {
+      process.env.JEST_PUPPETEER_CONFIG = 'nop.js'
+    })
+
+    it('should return an error if not found', async () => {
+      process.env.JEST_PUPPETEER_CONFIG = 'nop.js'
+      expect.assertions(1)
+      mockExists(false)
+      try {
+        await readConfig()
+      } catch (error) {
+        expect(error.message).toBe(
+          "Error: Can't find a root directory while resolving a config file path.\nProvided path to resolve: nop.js",
+        )
+      }
+    })
+
+    it('should return custom config', async () => {
+      process.env.JEST_PUPPETEER_CONFIG = path.resolve(
+        __dirname,
+        '__fixtures__/customConfig.js',
+      )
+      mockExists(true)
+      const config = await readConfig()
+      expect(config).toEqual({
+        launch: {},
+        server: { command: 'yarn babel-node src/server/main.js' },
+      })
+    })
+  })
+
+  describe('with default config path', () => {
+    beforeEach(() => {
+      process.env.JEST_PUPPETEER_CONFIG = ''
+    })
+
+    it('should return custom config', async () => {
+      mockExists(true)
+      const config = await readConfig()
+      expect(config.server).toBeDefined()
+    })
+
+    it('should return default config if not found', async () => {
+      mockExists(false)
+      const config = await readConfig()
+      expect(config).toEqual({ launch: {} })
+    })
+  })
+})