Changes suggested in review.

src/Css/CssDocument.php

@@ -13,6 +13,7 @@
 use Sabberworm\CSS\Renderable as CssRenderable;
 use Sabberworm\CSS\RuleSet\DeclarationBlock as CssDeclarationBlock;
 use Sabberworm\CSS\RuleSet\RuleSet as CssRuleSet;
+use Sabberworm\CSS\Settings as ParserSettings;
 
 /**
  * Parses and stores a CSS document from a string of CSS, and provides methods to obtain the CSS in parts or as data
@@ -36,25 +37,33 @@ class CssDocument
  private $isImportRuleAllowed = true;
 
  /**
- * @param string $css
+ * @param string $css {@see https://github.com/squizlabs/PHP_CodeSniffer/issues/3521}
  * @param bool $debug
  * If this is `true`, an exception will be thrown if invalid CSS is encountered.
  * Otherwise the parser will try to do the best it can.
  */
  public function __construct(string $css, bool $debug)
  {
  // CSS Parser currently throws exception with nested at-rules (like `@media`) in strict parsing mode
- // @see https://github.com/sabberworm/PHP-CSS-Parser/issues/127
- $parserSettings = \Sabberworm\CSS\Settings::create()->withLenientParsing(
- !$debug ||
- \preg_match('/@(?:media|supports|(?:-webkit-|-moz-|-ms-|-o-)?+(keyframes|document))\\b/', $css) === 1
- );
+ $parserSettings = ParserSettings::create()->withLenientParsing(!$debug || static::hasNestedAtRule($css));
 
  // CSS Parser currently throws exception with non-empty whitespace-only CSS in strict parsing mode, so `trim()`
  // @see https://github.com/sabberworm/PHP-CSS-Parser/issues/349
  $this->sabberwormCssDocument = (new CssParser(\trim($css), $parserSettings))->parse();
  }
 
+ /**
+ * Tests if a string of CSS appears to contain an at-rule with nested rules
+ * (`@media`, `@supports`, `@keyframes`, `@document`,
+ * the latter two additionally with vendor prefixes that may commonly be used).
+ *
+ * @see https://github.com/sabberworm/PHP-CSS-Parser/issues/127
+ */
+ private static function hasNestedAtRule(string $css): bool
+ {
+ return \preg_match('/@(?:media|supports|(?:-webkit-|-moz-|-ms-|-o-)?+(keyframes|document))\\b/', $css) === 1;
+ }
+
  /**
  * Collates the media query, selectors and declarations for individual rules from the parsed CSS, in order.
  *

tests/Unit/Css/CssDocumentTest.php

@@ -24,6 +24,11 @@ final class CssDocumentTest extends TestCase
  . ' font-family: "Foo Sans";' . "\n"
  . ' src: url("/foo-sans.woff2") format("woff2");' . "\n}";
 
+ private static function createDebugSubject(string $css): CssDocument
+ {
+ return new CssDocument($css, true);
+ }
+
  /**
  * @test
  *
@@ -436,8 +441,6 @@ public function provideCssWithoutNonConditionalAtRules(): array
  /**
  * @test
  *
- * @param string $css
- *
  * @dataProvider provideValidAtCharsetRules
  * @dataProvider provideInvalidAtCharsetRules
  */
@@ -453,8 +456,6 @@ public function discardsValidOrInvalidAtCharsetRuleNotInDebugMode(string $css):
  /**
  * @test
  *
- * @param string $css
- *
  * @dataProvider provideValidAtCharsetRules
  */
  public function discardsValidAtCharsetRuleInDebugMode(string $css): void
@@ -469,8 +470,6 @@ public function discardsValidAtCharsetRuleInDebugMode(string $css): void
  /**
  * @test
  *
- * @param string $css
- *
  * @dataProvider provideInvalidAtCharsetRules
  */
  public function throwsExceptionForOrDiscardsInvalidAtCharsetRuleInDebugMode(string $css): void
@@ -513,9 +512,6 @@ public function provideInvalidAtCharsetRules(): array
  /**
  * @test
  *
- * @param string $atRuleCss
- * @param string $cssBefore
- *
  * @dataProvider provideInvalidNonConditionalAtRule
  */
  public function discardsInvalidNonConditionalAtRuleNotInDebugMode(string $atRuleCss, string $cssBefore = ''): void
@@ -590,11 +586,6 @@ public function notRendersAtMediaRuleInNonConditionalAtRules(): void
  self::assertSame('', $result);
  }
 
- private static function createDebugSubject(string $css): CssDocument
- {
- return new CssDocument($css, true);
- }
-
  /**
  * Asserts that two strings are the same after `trim`ming both of them.
  *