Introduce unit tests for the `normalize_whitespace()` function.

Props mdbitz.
Fixes #26163.



git-svn-id: https://develop.svn.wordpress.org/trunk@26327 602fd350-edb4-49c9-b593-d223f7449a82

tests/phpunit/tests/formatting/NormalizeWhitespace.php

@@ -0,0 +1,52 @@
+<?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 ) );
+	}
+}