tests: add more cases

adds test cases for:
- (pass) lowercasing normalization
- (pass) whitespace removal around subtype
- (fail) empty type + empty subtype
- (fail) non-HTTP token codepoints within type and subtype

tests/MediaTypeParserTest.php

@@ -76,6 +76,18 @@ public function provideValidMediaTypes(): array {
 					'charset' => 'UTF-8',
 				],
 			],
+			[
+				'TexT/PlAin',
+				'text',
+				'plain',
+				[]
+			],
+			[
+				'text/ plain ',
+				'text',
+				'plain',
+				[],
+			],
 			[
 				'application/vnd.openxmlformats-officedocument.presentationml.presentation',
 				'application',
@@ -91,6 +103,10 @@ public function provideInvalidMediaTypes(): array {
 			[ '    ' ],
 			[ '\n\n\n\n\r\r\r' ],
 			[ 'text' ],
+			[ 'tex\t/plain' ],
+			[ 'text/pla\in' ],
+			[ '/plain' ],
+			[ 'text/' ],
 		];
 	}
 }