diff --git a/core/core.api.php b/core/core.api.php
index fb595fc..61e5e3b 100644
--- a/core/core.api.php
+++ b/core/core.api.php
@@ -1121,7 +1121,7 @@
  * - @link oo_conventions Object-oriented programming topic @endlink for more
  *   on PSR-4, namespaces, and where to place classes.
  *
- * @section write_functional_phpunit Write functional tests (phpunit)
+ * @section write_functional_phpunit Write functional PHP tests (phpunit)
  * Functional tests are written using the BrowserTestBase base class, and use
  * PHPUnit as their underlying framework. They use a simulated browser, in which
  * the test can click links, visit URLs, post to forms, etc. To write a
@@ -1133,7 +1133,8 @@
  *   migration process, the group core uses is migrate_drupal_6. Use yourmodule
  *   as the group name if the test does not belong to another larger group.
  * - You may also override the default setUp() method, which can be used to set
- *   up content types and similar procedures.
+ *   up content types and similar procedures. Don't forget to invoke the parent
+ *   method.
  * - In some cases, you may need to write a test module to support your test;
  *   put such modules under the yourmodule/tests/modules directory.
  * - Methods in your test class whose names start with 'test', and which have
@@ -1142,7 +1143,7 @@
  *   environment, so it can only rely on the setUp() method, not what has
  *   been set up by other test methods.
  *
- * @section write_jsfunctional_phpunit Write JavaScript tests (phpunit)
+ * @section write_jsfunctional_phpunit Write functional JavaScript tests (phpunit)
  * A lot of functionality relies on JavaScript. In order to allow people to
  * provide functional test coverage for this, Drupal provides the
  * JavascriptTestBase class, which works really similar to BrowserTestBase:
@@ -1151,8 +1152,8 @@
  *   the Drupal\Tests\yourmodule\FunctionalJavascript namespace
  * - Add a @group annotation. Use yourmodule as the group name if the test does
  *   not belong to another larger group.
- * - To run JavaScript tests, set up phantomjs, see core/tests/README.md.
- * - When clicking a link/button with Ajax behaviour attached, you need to keep
+ * - To run JavaScript tests, set up PhantomJS, see core/tests/README.md.
+ * - When clicking a link/button with Ajax behavior attached, you need to keep
  *   in mind that the underlying browser might need a while to deliver changes
  *   to the HTML. Use $this->assertSession()->assertWaitOnAjaxRequest() to wait
  *   for that.