Added jest config to support test utility modules. (#6154) [deploy]

docs/tests/frontend-tests.md

@@ -0,0 +1,41 @@
+---
+title: Frontend Tests
+---
+
+# Frontend Tests
+
+The test code is located within the same directory as each component, inside a
+`__tests__` directory.
+
+```shell
+$ tree app/javascript/article-form -L 1
+app/javascript/article-form
+├── __tests__
+└── articleForm.jsx
+```
+
+The testing library being used is [Jest](https://jestjs.io/).
+
+- For unit tests, use jest's [expect API](https://jestjs.io/docs/en/expect)
+- For snapshot testing of Preact components, use
+  [preact-render-spy](https://github.com/mzgoddard/preact-render-spy) and
+  [preact-render-to-json](https://github.com/nathancahill/preact-render-to-json).
+
+You can run those tests with:
+
+```shell
+npm run test
+```
+
+or
+
+```shell
+yarn test
+```
+
+At the end of the test's execution, you will see the code coverage for the
+Preact components in our codebase.
+
+If tests require utility modules, create them in a `utilities` folder under the
+`__tests__` folder. Jest is configured to not treat the `utilities` folder as a
+test suite.

docs/tests/preact-tests.md

@@ -1,32 +0,0 @@
----
-title: Preact Tests
----
-
-# Preact Tests
-
-The test code is located within the same directory as each component, inside a
-`__tests__` directory.
-
-```shell
-$ tree app/javascript/article-form -L 1
-app/javascript/article-form
-├── __tests__
-└── articleForm.jsx
-```
-
-The testing library being used is [Jest](https://jestjs.io/).
-
-You can run those tests with:
-
-```shell
-npm run test
-```
-
-or
-
-```shell
-yarn test
-```
-
-At the end of the test's execution, you will see the code coverage for the Preact
-components in our codebase.

docs/tests/readme.md

@@ -4,7 +4,7 @@ items:
   - acceptance-tests.md
   - integration-tests.md
   - unit-functional-tests.md
-  - preact-tests.md
+  - frontend-tests.md
   - accessibility-tests.md
   - regression-tests.md
   - code-coverage.md

jest.config.js

@@ -12,5 +12,10 @@ module.exports = {
   snapshotSerializers: ['preact-render-spy/snapshot'],
   // The webpack config folder for webpacker is excluded as it has a test.js file that gets
   // picked up by jest if this folder is not excluded causing a false negative of a test suite failing.
-  testPathIgnorePatterns: ['/node_modules/', './config/webpack'],
+  testPathIgnorePatterns: [
+    '/node_modules/',
+    './config/webpack',
+    // Allows developers to add utility modules that jest won't run as test suites.
+    '/__tests__/utilities/',
+  ],
 };