fix(e2e-nightwatch): check for correct flag name (vuejs#5016)

* fix(e2e-nightwatch): check for correct flag name

flag is documented as `--use-selenium` but we checked for `args['with-selenium']`
fix vuejs#5015

* test(e2e-nightwatch): selenium test
uses correct flag now

Author: LinusBorg

packages/@vue/cli-plugin-e2e-nightwatch/__tests__/nightwatchPlugin.spec.js

@@ -69,7 +69,7 @@ describe('nightwatch e2e plugin', () => {
   })
 
   test('should run single test with custom nightwatch.json and selenium server', async () => {
-    await project.run(`vue-cli-service test:e2e --headless --with-selenium -t tests/e2e/specs/test.js`)
+    await project.run(`vue-cli-service test:e2e --headless --use-selenium -t tests/e2e/specs/test.js`)
     let results = await project.read('test_results.json')
     results = JSON.parse(results)
 

packages/@vue/cli-plugin-e2e-nightwatch/index.js

@@ -65,7 +65,7 @@ module.exports = (api, options) => {
         rawArgs.push('--env', 'chrome')
       }
 
-      if (args['with-selenium']) {
+      if (args['use-selenium']) {
         process.env.VUE_NIGHTWATCH_USE_SELENIUM = '1'
       }