[Testing] Restructure/rewrite testing docs

.doctor-rst.yaml

@@ -95,3 +95,4 @@ whitelist:
         - ".. _`Deploying Symfony 4 Apps on Heroku`: https://devcenter.heroku.com/articles/deploying-symfony4"
         - '.. versionadded:: 0.2' # MercureBundle
         - '.. code-block:: twig'
+        - 'End to End Tests (E2E)'

best_practices.rst

@@ -399,8 +399,8 @@ Smoke Test your URLs
 
 In software engineering, `smoke testing`_ consists of *"preliminary testing to
 reveal simple failures severe enough to reject a prospective software release"*.
-Using :ref:`PHPUnit data providers <testing-data-providers>` you can define a
-functional test that checks that all application URLs load successfully::
+Using `PHPUnit data providers`_ you can define a functional test that
+checks that all application URLs load successfully::
 
     // tests/ApplicationAvailabilityFunctionalTest.php
     namespace App\Tests;
@@ -454,3 +454,4 @@ you must set up a redirection.
 .. _`feature toggles`: https://en.wikipedia.org/wiki/Feature_toggle
 .. _`smoke testing`: https://en.wikipedia.org/wiki/Smoke_testing_(software)
 .. _`Webpack`: https://webpack.js.org/
+.. _`PHPUnit data providers`: https://phpunit.readthedocs.io/en/stable/writing-tests-for-phpunit.html#data-providers

form/unit_testing.rst

@@ -121,8 +121,8 @@ variable exists and will be available in your form themes::
 
 .. tip::
 
-    Use :ref:`PHPUnit data providers <testing-data-providers>` to test multiple
-    form conditions using the same test code.
+    Use `PHPUnit data providers`_ to test multiple form conditions using
+    the same test code.
 
 .. caution::
 
@@ -242,3 +242,5 @@ guessers using the :method:`Symfony\\Component\\Form\\Test\\FormIntegrationTestC
 :method:`Symfony\\Component\\Form\\Test\\FormIntegrationTestCase::getTypeExtensions`
 and :method:`Symfony\\Component\\Form\\Test\\FormIntegrationTestCase::getTypeGuessers`
 methods.
+
+.. _`PHPUnit data providers`: https://phpunit.readthedocs.io/en/stable/writing-tests-for-phpunit.html#data-providers