Add running tests to FE tips doc

doc/development/new_fe_guide/tips.md

@@ -23,3 +23,7 @@ Your feature flag can now be:
 - [Deleting a feature flag](../../api/features.md#delete-a-feature)
 - [Manage feature flags](../feature_flags/process.md)
 - [Feature flags API](../../api/features.md)
+
+## Running tests locally
+
+This can be done as outlined by the [frontend testing guide](../testing_guide/frontend_testing.md#running-frontend-tests).

doc/development/testing_guide/frontend_testing.md

@@ -552,6 +552,7 @@ For running the frontend tests, you need the following commands:
 
 - `rake frontend:fixtures` (re-)generates [fixtures](#frontend-test-fixtures).
 - `yarn test` executes the tests.
+- `yarn jest` executes only the Jest tests.
 
 As long as the fixtures don't change, `yarn test` is sufficient (and saves you some time).
 
@@ -593,6 +594,24 @@ glob otherwise your shell may split it into multiple arguments:
 yarn karma -f 'spec/javascripts/ide/**/file_spec.js'
 ```
 
+It is also possible to target individual Jest / RSpec tests:
+
+```bash
+# Run specific jest file
+yarn jest ./path/to/local_spec.js
+# Run specific jest folder
+yarn jest ./path/to/folder/
+# Run all jest files which path contain term
+yarn jest term
+```
+
+```bash
+# Run specific rspec file
+rspec ./path/to/local_spec.rb
+# Run specific block within rspec file
+rspec ./path/to/local_spec.rb:15
+```
+
 ## Frontend test fixtures
 
 Code that is added to HAML templates (in `app/views/`) or makes Ajax requests to the backend has tests that require HTML or JSON from the backend.