How can I retry failed end to end tests in Detox using Mocha? - react-native

Question

I have a flaky end-to-end test that uses Detox and Mocha.
The Mocha test runner allows for multiple retries. I tried using the recommended Mocha syntax:
// auth.spec.js
describe('App authentication', () => {
this.retries(2);
it('should have a login screen', async () => {
await expect(element(by.id('LoginScreenView'))).toBeVisible();
});
});
However, it appears this is an empty object ({}) and does not have a retries function when running Detox with Mocha as the test runner.
It generates the following error:
node_modules/.bin/mocha __e2e__ --opts __e2e__/config/mocha.opts --
configuration ios.sim.debug --grep :android: --invert --artifacts-location "__e2e__/artifacts/ios.sim.debug.2018-10-17 22-51-12Z"
/<path>/__e2e__/auth.spec.js:10
this.retries(2);
^
TypeError: this.retries is not a function
at Suite.describe (/<path>/__e2e__/auth.spec.js:4:8)
at Object.create (/<path>/node_modules/mocha/lib/interfaces/common.js:112:19)
at context.describe.context.context (/<path>/node_modules/mocha/lib/interfaces/bdd.js:40:27)
at Object.<anonymous> (/<path>/__e2e__/auth.spec.js:3:1)
at Module._compile (module.js:652:30)
at Object.Module._extensions..js (module.js:663:10)
at Module.load (module.js:565:32)
at tryModuleLoad (module.js:505:12)
at Function.Module._load (module.js:497:3)
at Module.require (module.js:596:17)
at require (internal/module.js:11:18)
at /<path>/node_modules/mocha/lib/mocha.js:250:27
at Array.forEach (<anonymous>)
at Mocha.loadFiles (/<path>/node_modules/mocha/lib/mocha.js:247:14)
at Mocha.run (/<path>/node_modules/mocha/lib/mocha.js:576:10)
at Object.<anonymous> (/<path>/node_modules/mocha/bin/_mocha:637:18)
at Module._compile (module.js:652:30)
at Object.Module._extensions..js (module.js:663:10)
at Module.load (module.js:565:32)
at tryModuleLoad (module.js:505:12)
at Function.Module._load (module.js:497:3)
at Function.Module.runMain (module.js:693:10)
at startup (bootstrap_node.js:188:16)
at bootstrap_node.js:609:3
child_process.js:644
throw err;
^
Is there a way to automatically retry failed tests in Detox?

Answer 1

this in mocha can't work with arrow function, so must change it into ordinary one
// auth.spec.js
describe('App authentication', function () { // change it
this.retries(2);
It is not recommended best practice to use in Mocha
Ref:
https://mochajs.org/#arrow-functions
Hope it helps