Add test coverage

A few minor fixes, otherwise looks really good and thorough!

1. +++ b/tests/src/Functional/UiTest.php
   @@ -0,0 +1,256 @@
   +  public function testBuildHooksUi() {
   

   Missing a doc block here

2. +++ b/tests/src/Functional/UiTest.php
   @@ -0,0 +1,256 @@
   +   * Assert that anonymous uses can't access privileged pages.
   

   s/uses/users for the 3 assert functions

3. +++ b/tests/src/Functional/UiTest.php
   @@ -0,0 +1,256 @@
   +  private function assertFrontEndEnvironmentDeploymentFormFunctionality(
   +    FrontendEnvironmentInterface $environment
   +  ) {
   

   Does this need to be split over 3 lines?

Thanks!