Convert drupal_clean_css_identifier() to a component

+++ b/core/lib/Drupal/Component/Utility/CSS.php
@@ -0,0 +1,46 @@
+   * http://www.w3.org/TR/CSS21/syndata.html#characters shows the syntax for valid

nitpick: 80 chars

Other than that looks good to go to me.

1. +++ b/core/lib/Drupal/Component/Utility/CSS.php
   @@ -0,0 +1,47 @@
   +   *
   +   * @param $identifier
   +   *   The identifier to clean.
   +   * @param $filter
   +   *   An array of string replacements to use on the identifier.
   +   *
   +   * @return
   +   *   The cleaned identifier.
   +   */
   

   Let's document the variable types as well.

2. +++ b/core/tests/Drupal/Tests/Component/Utility/CSSTest.php
   @@ -0,0 +1,66 @@
   +/**
   + * Tests cleaning HTML identifiers.
   + */
   +class CSSTest extends UnitTestCase {
   

   It would be cool to have a @see (the class we test) and a @group Drupal

3. +++ b/core/tests/Drupal/Tests/Component/Utility/CSSTest.php
   @@ -0,0 +1,66 @@
   +  public static function getInfo() {
   

   Let's introduce an empty line in here.

4. +++ b/core/tests/Drupal/Tests/Component/Utility/CSSTest.php
   @@ -0,0 +1,66 @@
   +   * Tests that drupal_clean_css_identifier() cleans the identifier properly.
   +   *
   

   Should we just point to the CSS::cleanIdentifier method?

5. +++ b/core/tests/Drupal/Tests/Component/Utility/CSSTest.php
   @@ -0,0 +1,66 @@
   +  public function provider() {
   

   We kind of have the "standard" in core to use providerTestNameofTheTest, so here providerTestDrupalCleanCSSIdenfier ... just mentioning as there are some small other points.

+++ b/core/lib/Drupal/Component/Utility/CSS.php
@@ -0,0 +1,47 @@
+class CSS {

+++ b/core/tests/Drupal/Tests/Component/Utility/CSSTest.php
@@ -0,0 +1,66 @@
+class CSSTest extends UnitTestCase {

should be
Css and CssTest

This should cover all points in #5 and #6 as well as a much needed reroll.

#7: drupal_clean_css_identifier-to-component-2082103-7.patch queued for re-testing.

So it turns out I completely duplicated the work of this issue.
I was working on #2121713: Move drupal_html_id() and drupal_html_class() to Drupal\Component\Utility, which forced me to do drupal_clean_css_identifier as well...

Want to merge them?

Updated the other issue to ensure you get commit credit, closing.