Build/Test Tools: Begin eliminating unnecessary randomness in tests.

Although unlikely, clashes in randomly generated strings could cause unexpected failures. In addition, most randomness is entirely unnecessary, is bad practice, and increases test time (however small it may be).

See #37371


git-svn-id: https://develop.svn.wordpress.org/trunk@38762 602fd350-edb4-49c9-b593-d223f7449a82

tests/phpunit/tests/link/getPreviewPostLink.php

@@ -52,7 +52,7 @@ class Tests_Link_GetPreviewPostLink extends WP_UnitTestCase {
 	}
 
 	public function test_get_preview_post_link_should_return_empty_string_for_non_viewable_post_type() {
-		$post_type = register_post_type( rand_str(12), array(
+		$post_type = register_post_type( 'non_viewable_cpt', array(
 			'public' => false,
 		) );