test: remove mocha and nyc

Author: gr2m

.gitignore

@@ -1,4 +1,3 @@
-.nyc_output
 coverage
 node_modules
 

CONTRIBUTING.md

@@ -38,12 +38,9 @@ $ npm test
 Or run a specific test
 
 ```bash
-$ ./node_modules/.bin/mocha test/scenarios/get-repository-test.js
+$ ./node_modules/.bin/jest test/integration/smoke.test.js
 ```
 
-**Note**: In order to run the same [scenario tests](test/scenarios) in both Node
-and browser, we simulate the Cypress environment in Node, see [test/mocha-node-setup.js](test/mocha-node-setup.js).
-
 The examples are run as part of the tests. You can set an `EXAMPLES_GITHUB_TOKEN` environment
 variable (or set it in a `.env` file) to avoid running against GitHub's rate limit.