Add css builder tests

Author: sirreal

tests/phpunit/tests/css-api/wpCssBuilder.php

@@ -0,0 +1,85 @@
+<?php
+
+/**
+ * Tests for the WP_CSS_Builder class.
+ *
+ * @group css-api
+ *
+ * @coversDefaultClass WP_CSS_Builder
+ */
+class Tests_CssApi_WpCssBuilder extends WP_UnitTestCase {
+	/**
+	 * @dataProvider data_string_escaping
+	 *
+	 * @covers ::string
+	 */
+	public function test_string_escaping( string $input, string $expected ): void {
+		$this->assertSame( $expected, WP_CSS_Builder::string( $input ) );
+	}
+
+	/**
+	 * Data provider for individual escape mappings and basic cases.
+	 *
+	 * @return array
+	 */
+	public static function data_string_escaping(): array {
+		return array(
+			// Basic behavior.
+			'empty string'          => array( '', '""' ),
+			'simple ASCII'          => array( 'hello', '"hello"' ),
+			'spaces preserved'      => array( 'hello world', '"hello world"' ),
+			'numbers pass through'  => array( '12345', '"12345"' ),
+			'non-ASCII passthrough' => array( 'café', '"café"' ),
+
+			// Backslash escaping.
+			'single backslash'      => array( '\\', '"\5C "' ),
+			'double backslash'      => array( '\\\\', '"\5C \5C "' ),
+
+			// NULL byte.
+			'null byte'             => array( "\0", "\"\u{FFFD}\"" ),
+
+			// Newline variants.
+			'LF'                    => array( "\n", '"\A "' ),
+			'CR'                    => array( "\r", '"\A "' ),
+			'CRLF'                  => array( "\r\n", '"\A "' ),
+			'form feed'             => array( "\f", '"\A "' ),
+
+			// HTML-problematic characters.
+			'less than'             => array( '<', '"\3C "' ),
+			'greater than'          => array( '>', '"\3E "' ),
+			'ampersand'             => array( '&', '"\26 "' ),
+
+			// CSS-problematic characters.
+			'comma'                 => array( ',', '"\2C "' ),
+			'semicolon'             => array( ';', '"\3B "' ),
+			'open brace'            => array( '{', '"\7B "' ),
+			'close brace'           => array( '}', '"\7D "' ),
+			'double quote'          => array( '"', '"\22 "' ),
+			'single quote'          => array( "'", '"\27 "' ),
+		);
+	}
+
+	/**
+	 * Tests the example from the class docblock.
+	 *
+	 * @covers ::string
+	 */
+	public function test_docblock_example(): void {
+		$value    = 'CSS & a "<style>" tag\'s strings';
+		$expected = '"CSS \26  a \22 \3C style\3E \22  tag\27 s strings"';
+
+		$this->assertSame( $expected, WP_CSS_Builder::string( $value ) );
+	}
+
+	/**
+	 * Tests a string containing mixed newline types.
+	 *
+	 * @covers ::string
+	 */
+	public function test_mixed_newlines(): void {
+		$input    = "line1\nline2\rline3\r\nline4\fline5";
+		$expected = '"line1\A line2\A line3\A line4\A line5"';
+
+		$this->assertSame( $expected, WP_CSS_Builder::string( $input ) );
+	}
+}