Issue #3006625 by Lendude, borisson_: 'stylesheets-remove' test is broken

core/modules/system/tests/src/Functional/Theme/ThemeTest.php

@@ -94,7 +94,11 @@ public function testCSSOverride() {
     $config->set('css.preprocess', 0);
     $config->save();
     $this->drupalGet('theme-test/suggestion');
-    $this->assertNoText('js.module.css', 'The theme\'s .info.yml file is able to override a module CSS file from being added to the page.');
+    // We add a "?" to the assertion, because drupalSettings may include
+    // information about the file; we only really care about whether it appears
+    // in a LINK or STYLE tag, for which Drupal always adds a query string for
+    // cache control.
+    $this->assertSession()->responseNotContains('js.module.css?');
 
     // Also test with aggregation enabled, simply ensuring no PHP errors are
     // triggered during drupal_build_css_cache() when a source file doesn't

core/modules/system/tests/themes/test_theme/test_theme.info.yml

@@ -16,7 +16,7 @@ base theme: classy
 core: 8.x
 logo: images/logo2.svg
 stylesheets-remove:
-  - '@system/css/js.module.css'
+  - '@stable/css/system/components/js.module.css'
 libraries:
   - test_theme/global-styling
 libraries-override: