Replace mocha with jest (#470)

* Replace mocha with jest

* Remove unnecessary @babel/register

* Move chai setup to each test file

This allows us moving to Jest built-in matchers one test file at a time

* Remove xvfb from github workflow

* Move timeout configuration to describe block

* Use spawn instead of exec

.github/workflows/main.yml

@@ -29,10 +29,8 @@ jobs:
       - name: Build sources
         run: npm run build
 
-      - name: Run tests with xvfb available
-        uses: GabrielBB/xvfb-action@v1
-        with:
-          run: npm run test
+      - name: Run tests
+        run: npm run test
 
   lint:
     runs-on: ubuntu-latest

jest.config.js

@@ -0,0 +1,20 @@
+// Jest configuration
+// Reference: https://jestjs.io/docs/configuration
+
+module.exports = {
+  testMatch: [
+    '**/test/*.js'
+  ],
+  testPathIgnorePatterns: [
+    '<rootDir>/test/helpers.js'
+  ],
+  setupFilesAfterEnv: [
+    '<rootDir>/test/helpers.js'
+  ],
+  watchPathIgnorePatterns: [
+    // Ignore the output generated by plugin tests
+    // when watching for changes to avoid the test
+    // runner continuously re-running tests
+    '<rootDir>/test/output'
+  ]
+};