Merge pull request jest-community#1 from stephtr/feature/improve-jest-detection

Extract `nodeBinExtension` as variable

Author: rfgamaral

src/helpers.ts

@@ -9,6 +9,26 @@ import { IPluginResourceSettings, hasUserSetPathToJest } from './Settings'
  */
 const createReactAppBinaryNames = ['react-scripts', 'react-native-scripts', 'react-scripts-ts', 'react-app-rewired']
 
+/**
+ * File extension for npm binaries
+ */
+export const nodeBinExtension: string = platform() === 'win32' ? '.cmd' : ''
+
+/**
+ * Resolves the location of an npm binary
+ */
+function getLocalPathForExecutable(rootPath: string, executable: string): string {
+  return normalize(join(rootPath, 'node_modules', '.bin', executable + nodeBinExtension))
+}
+
+/**
+ * Checks whether an npm binary exists
+ */
+function hasNodeExecutable(rootPath: string, executable: string): boolean {
+  const absolutePath = getLocalPathForExecutable(rootPath, executable)
+  return existsSync(absolutePath)
+}
+
 /**
  * Tries to read the test command from the scripts section within `package.json`
  *
@@ -49,21 +69,6 @@ function isBootstrappedWithCreateReactApp(rootPath: string): boolean {
   return isCreateReactAppTestCommand(testCommand)
 }
 
-function getPlatformJestExecutable(executable: string): string {
-  const ext = platform() === 'win32' ? '.cmd' : ''
-  return executable + ext
-}
-
-function getLocalPathForExecutable(rootPath: string, executable: string): string {
-  const platformExecutable = getPlatformJestExecutable(executable)
-  return normalize(join(rootPath, 'node_modules', '.bin', platformExecutable))
-}
-
-function hasNodeExecutable(rootPath: string, executable: string): boolean {
-  const absolutePath = getLocalPathForExecutable(rootPath, executable)
-  return existsSync(absolutePath)
-}
-
 /**
  * Handles getting the jest runner, handling the OS and project specific work too
  *
@@ -84,7 +89,7 @@ export function pathToJest({ pathToJest, rootPath }: IPluginResourceSettings) {
     return localJestExecutable
   }
 
-  return getPlatformJestExecutable('jest')
+  return 'jest' + nodeBinExtension
 }
 
 /**
@@ -124,7 +129,7 @@ export function pathToJestPackageJSON(pluginSettings: IPluginResourceSettings):
   return null
 }
 
-function removeSurroundingQuotes(str) {
+function removeSurroundingQuotes(str: string) {
   return str.replace(/^['"`]/, '').replace(/['"`]$/, '')
 }
 

tests/helpers.test.ts

@@ -18,10 +18,28 @@ jest.mock('path', () => ({
   normalize: mockNormalize,
 }))
 
-import { isCreateReactAppTestCommand, pathToJest, pathToJestPackageJSON } from '../src/helpers'
+import { isCreateReactAppTestCommand, pathToJest, pathToJestPackageJSON, nodeBinExtension } from '../src/helpers'
 import * as path from 'path'
 
+// Manually (forcefully) set the executable's file extension to test its addition independendly of the operating system.
+;(nodeBinExtension as string) = '.TEST'
+
 describe('ModuleHelpers', () => {
+  describe('nodeBinExtension', () => {
+    // Since `nodeBinExtension` is a variable, we have to reload the module in order to re-evaluate it.
+    it('should return an empty string on Linux', () => {
+      jest.resetModules()
+      mockPlatform.mockReturnValueOnce('linux')
+      expect(require('../src/helpers').nodeBinExtension).toBe('')
+    })
+
+    it('should equal ".cmd" on Windows', () => {
+      jest.resetModules()
+      mockPlatform.mockReturnValueOnce('win32')
+      expect(require('../src/helpers').nodeBinExtension).toBe('.cmd')
+    })
+  })
+
   describe('pathToJestPackageJSON', () => {
     const defaultPathToJest = null
     const defaultSettings: any = {
@@ -145,6 +163,12 @@ describe('ModuleHelpers', () => {
       rootPath: '',
     }
 
+    beforeEach(() => {
+      mockJoin.mockImplementation(require.requireActual('path').join)
+      mockNormalize.mockImplementation(require.requireActual('path').normalize)
+      mockExistsSync.mockImplementation(require.requireActual('path').existsSync)
+    })
+
     it('returns "npm test --" when bootstrapped with create-react-app', () => {
       mockReadFileSync.mockReturnValueOnce(
         JSON.stringify({
@@ -170,52 +194,24 @@ describe('ModuleHelpers', () => {
       expect(mockNormalize).toBeCalledWith(settings.pathToJest)
     })
 
-    describe('os platform: linux', () => {
-      it('defaults to "node_modules/.bin/jest" when Jest is locally installed', () => {
-        const expected = 'node_modules/.bin/jest'
+    it('defaults to "node_modules/.bin/jest" when Jest is locally installed', () => {
+      const expected = 'node_modules/.bin/jest.TEST'
 
-        mockJoin.mockImplementation(require.requireActual('path').posix.join)
-        mockPlatform.mockReturnValue('linux')
-        mockNormalize.mockImplementationOnce(arg => arg)
-        mockExistsSync.mockImplementation(path => path === expected)
+      mockJoin.mockImplementation(require.requireActual('path').posix.join)
+      mockNormalize.mockImplementation(arg => arg)
+      mockExistsSync.mockImplementation(path => path === expected)
 
-        expect(pathToJest(defaultSettings)).toBe(expected)
-      })
-
-      it('defaults to "jest" when Jest is locally installed', () => {
-        const expected = 'jest'
-
-        mockJoin.mockImplementation(require.requireActual('path').posix.join)
-        mockPlatform.mockReturnValue('linux')
-        mockNormalize.mockImplementationOnce(arg => arg)
-        mockExistsSync.mockImplementation(_ => false)
-
-        expect(pathToJest(defaultSettings)).toBe(expected)
-      })
+      expect(pathToJest(defaultSettings)).toBe(expected)
     })
 
-    describe('os platform: win32', () => {
-      it('defaults to "node_modules/.bin/jest.cmd" when Jest is locally installed', () => {
-        const expected = 'node_modules/.bin/jest.cmd'
+    it('defaults to "jest" when Jest is not locally installed', () => {
+      const expected = 'jest.TEST'
 
-        mockJoin.mockImplementation(require.requireActual('path').posix.join)
-        mockPlatform.mockReturnValue('win32')
-        mockNormalize.mockImplementationOnce(arg => arg)
-        mockExistsSync.mockImplementation(path => path === expected)
+      mockJoin.mockImplementation(require.requireActual('path').posix.join)
+      mockNormalize.mockImplementation(arg => arg)
+      mockExistsSync.mockImplementation(_ => false)
 
-        expect(pathToJest(defaultSettings)).toBe(expected)
-      })
-
-      it('defaults to "jest.cmd" when Jest is locally installed', () => {
-        const expected = 'jest.cmd'
-
-        mockJoin.mockImplementation(require.requireActual('path').posix.join)
-        mockPlatform.mockReturnValue('win32')
-        mockNormalize.mockImplementationOnce(arg => arg)
-        mockExistsSync.mockImplementation(_ => false)
-
-        expect(pathToJest(defaultSettings)).toBe(expected)
-      })
+      expect(pathToJest(defaultSettings)).toBe(expected)
     })
   })
 })