docs: Add test file location -> test runner table (elastic#34986) (el…

…astic#35345)

* docs: Add test file location -> test runner table

* Use scripts/mocha instead of if yarn test:mocha and clarify arguments

* docs: add some examples of running tests suites with grep patterns

* Split out x-pack testing docs, add test runner column

* Split out x-pack testing docs, add test runner column #2

* Use node scripts for jest and split functional runner/server

CONTRIBUTING.md

@@ -303,19 +303,36 @@ macOS users on a machine with a discrete graphics card may see significant speed
 `yarn debug` will start the server with Node's inspect flag. Kibana's development mode will start three processes on ports `9229`, `9230`, and `9231`. Chrome's developer tools need to be configured to connect to all three connections. Add `localhost:<port>` for each Kibana process in Chrome's developer tools connection tab.
 
 ### Unit testing frameworks
-Kibana is migrating unit testing from Mocha to Jest. Legacy unit tests still exist in Mocha but all new unit tests should be written in Jest.
-
-#### Mocha (legacy)
-Mocha tests are contained in `__tests__` directories.
-
-#### Jest
-Jest tests are stored in the same directory as source code files with the `.test.js` suffix.
-
-### Running Jest Unit Tests
-
-```bash
-node scripts/jest
-```
+Kibana is migrating unit testing from Mocha to Jest. Legacy unit tests still
+exist in Mocha but all new unit tests should be written in Jest. Mocha tests
+are contained in `__tests__` directories. Whereas Jest tests are stored in
+the same directory as source code files with the `.test.js` suffix.
+
+### Running specific Kibana tests
+
+The following table outlines possible test file locations and how to invoke them:
+
+| Test runner        | Test location                                                                                                                                           | Runner command (working directory is kibana root)                                       |
+| -----------------  | ------------------------------------------------------------------------------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------- |
+| Jest               | `src/**/*.test.js`<br>`src/**/*.test.ts`                                                                                                                | `node scripts/jest -t regexp [test path]`                                                  |
+| Jest (integration) | `**/integration_tests/**/*.test.js`                                                                                                                     | `node scripts/jest_integration -t regexp [test path]`                                   |
+| Mocha              | `src/**/__tests__/**/*.js`<br>`packages/kbn-datemath/test/**/*.js`<br>`packages/kbn-dev-utils/src/**/__tests__/**/*.js`<br>`tasks/**/__tests__/**/*.js` | `node scripts/mocha --grep=regexp [test path]`                                          |
+| Functional         | `test/*integration/**/config.js`<br>`test/*functional/**/config.js`                                                                                     | `node scripts/functional_tests_server --config test/[directory]/config.js`<br>`node scripts/functional_test_runner --config test/[directory]/config.js --grep=regexp`       |
+
+For X-Pack tests located in `x-pack/` see [X-Pack Testing](x-pack/README.md#testing)
+
+Test runner arguments:
+ - Where applicable, the optional arguments `-t=regexp` or `--grep=regexp` will only run tests or test suites whose descriptions matches the regular expression.
+ - `[test path]` is the relative path to the test file.
+
+ Examples:
+  - Run the entire elasticsearch_service test suite with yarn:
+    `node scripts/jest src/core/server/elasticsearch/elasticsearch_service.test.ts`
+  - Run the jest test case whose description matches 'stops both admin and data clients':
+    `node scripts/jest -t 'stops both admin and data clients' src/core/server/elasticsearch/elasticsearch_service.test.ts`
+  - Run the api integration test case whose description matches the given string:
+    `node scripts/functional_tests_server --config test/api_integration/config.js`
+    `node scripts/functional_tests_runner --config test/api_integration/config.js --grep='should return 404 if id does not match any sample data sets'`
 
 ### Debugging Unit Tests
 

x-pack/README.md

@@ -13,8 +13,22 @@ Elasticsearch will run with a basic license. To run with a trial license, includ
 Example: `yarn es snapshot --license trial --password changeme`
 
 # Testing
+## Running specific tests
+| Test runner  | Test location                                                                       | Runner command (working directory is kibana/x-pack)                                     |
+| ------------ | ----------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------- |
+| Jest         | `x-pack/**/*.test.js`<br>`x-pack/**/*.test.ts`                                      | `cd x-pack && node scripts/jest -t regexp [test path]`                                     |
+| Functional   | `x-pack/test/*integration/**/config.js`<br>`x-pack/test/*functional/config.js`      | `node scripts/functional_tests_server --config x-pack/test/[directory]/config.js`<br>`node scripts/functional_test_runner --config x-pack/test/[directory]/config.js --grep=regexp`       |
 
-## Running unit tests_bundle
+Examples:
+  - Run the jest test case whose description matches 'filtering should skip values of null':
+    `cd x-pack && yarn test:jest -t 'filtering should skip values of null' plugins/ml/public/explorer/explorer_charts/explorer_charts_container_service.test.js`
+  - Run the x-pack api integration test case whose description matches the given string:
+    `node scripts/functional_tests_server --config x-pack/test/api_integration/config.js`
+    `node scripts/functional_test_runner --config x-pack/test/api_integration/config.js --grep='apis Monitoring Beats list with restarted beat instance should load multiple clusters'`
+
+In addition to to providing a regular expression argument, specific tests can also be run by appeding `.only` to an `it` or `describe` function block. E.g. `describe(` to `describe.only(`.
+
+## Running all tests
 
 You can run unit tests by running:
 
@@ -28,15 +42,6 @@ If you want to run tests only for a specific plugin (to save some time), you can
 yarn test --plugins <plugin>[,<plugin>]*    # where <plugin> is "reporting", etc.
 ```
 
-#### Running single test file
-Edit test file, changing top level `describe` to `describe.only`. Run tests with normal commands.
-
-#### Running Jest Unit Tests
-```bash
-# from x-pack folder
-node scripts/jest
-```
-
 #### Debugging browser tests
 ```
 yarn test:browser:dev