wordpress-develop/tests/phpunit/tests/formatting/NormalizeWhitespace.php

<?php
/**
 * @group formatting
 */
class Tests_Formatting_NormalizeWhitespace extends WP_UnitTestCase {
	/**
	 * WhitespaceTest Content DataProvider
	 *
	 * array( input_txt, converted_output_txt)
	 */
	public function get_input_output() {
		return array (
			array (
				"		",
				""
			),
			array (
				"\rTEST\r",
				"TEST"
			),
			array (
				"\r\nMY TEST CONTENT\r\n",
				"MY TEST CONTENT"
			),
			array (
				"MY\r\nTEST\r\nCONTENT ",
				"MY\nTEST\nCONTENT"
			),
			array (
				"\tMY\rTEST\rCONTENT ",
				"MY\nTEST\nCONTENT"
			),
			array (
				"\tMY\t\t\tTEST\r\t\t\rCONTENT ",
				"MY TEST\n \nCONTENT"
			),
			array (
				"\tMY TEST \t\t\t CONTENT ",
				"MY TEST CONTENT"
			),
		);
	}

	/**
	 * Validate the normalize_whitespace function
	 *
	 * @dataProvider get_input_output
	 */
	function test_normalize_whitespace( $in_str, $exp_str ) {
		$this->assertEquals($exp_str, normalize_whitespace( $in_str ) );
	}
}