[BUGFIX] Parse @font-face src property as comma-delimited list

Fixes #789.

Also adds an initial `TestCase` for `Rule/Rule`.

CHANGELOG.md

@@ -42,6 +42,7 @@ Please also have a look at our
 
 ### Fixed
 
+- Parse `@font-face` `src` property as comma-delimited list (#790)
 - Fix type errors in PHP strict mode (#664)
 - Fix undefined local variable in `CalcFunction::parse()` (#593)
 - Fix PHP notice caused by parsing invalid color values having less than 6

src/Rule/Rule.php

@@ -117,13 +117,21 @@ public static function parse(ParserState $oParserState): Rule
      * @param string $sRule
      *
      * @return array<int, string>
+     * The first item is the innermost separator (or, put another way, the highest-precedence operator).
+     * The sequence continues to the outermost separator (or lowest-precedence operator).
      */
     private static function listDelimiterForRule($sRule): array
     {
         if (\preg_match('/^font($|-)/', $sRule)) {
             return [',', '/', ' '];
         }
-        return [',', ' ', '/'];
+
+        switch ($sRule) {
+            case 'src':
+                return [' ', ','];
+            default:
+                return [',', ' ', '/'];
+        }
     }
 
     /**

tests/Rule/RuleTest.php

@@ -0,0 +1,58 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Sabberworm\CSS\Tests\Value;
+
+use PHPUnit\Framework\TestCase;
+use Sabberworm\CSS\Parsing\ParserState;
+use Sabberworm\CSS\Settings;
+use Sabberworm\CSS\Rule\Rule;
+use Sabberworm\CSS\Value\RuleValueList;
+use Sabberworm\CSS\Value\ValueList;
+
+/**
+ * @covers \Sabberworm\CSS\Rule\Rule
+ */
+final class RuleTest extends TestCase
+{
+    /**
+     * @return array<string, array{0: string, 1: array<int, string>}>
+     */
+    public static function provideRulesAndExpectedParsedValueListTypes(): array
+    {
+        return [
+            'src (e.g. in @font-face)' => [
+                "
+                    src: url('../fonts/open-sans-italic-300.woff2') format('woff2'),
+                         url('../fonts/open-sans-italic-300.ttf') format('truetype');
+                ",
+                [RuleValueList::class, RuleValueList::class],
+            ],
+        ];
+    }
+
+    /**
+     * @test
+     *
+     * @param array<int, string> $expectedTypeClassnames
+     *
+     * @dataProvider provideRulesAndExpectedParsedValueListTypes
+     */
+    public function parsesValuesIntoExpectedTypeList(string $rule, array $expectedTypeClassnames): void
+    {
+        $subject = Rule::parse(new ParserState($rule, Settings::create()));
+
+        $value = $subject->getValue();
+        self::assertInstanceOf(ValueList::class, $value);
+
+        $actualClassnames = \array_map(
+            function ($component): string {
+                return \get_class($component);
+            },
+            $value->getListComponents()
+        );
+
+        self::assertSame($expectedTypeClassnames, $actualClassnames);
+    }
+}