diff --git a/tests/phpunit/tests/formatting/WpReplaceInHtmlTags.php b/tests/phpunit/tests/formatting/WpReplaceInHtmlTags.php
new file mode 100755
index 0000000000..f76fe0ac76
--- /dev/null
+++ b/tests/phpunit/tests/formatting/WpReplaceInHtmlTags.php
@@ -0,0 +1,37 @@
+<?php
+
+/**
+ * @group formatting
+ */
+class Tests_Formatting_WpReplaceInTags extends WP_UnitTestCase {
+	/**
+	 * Check for expected behavior of new function wp_replace_in_html_tags().
+	 *
+	 * @dataProvider data_wp_replace_in_html_tags
+	 */
+	function test_wp_replace_in_html_tags( $input, $output ) {
+		return $this->assertEquals( $output, wp_replace_in_html_tags( $input, array( "\n" => " " ) ) );
+	}
+
+	function data_wp_replace_in_html_tags() {
+		return array(
+			array(
+				"Hello \n World",
+				"Hello \n World",
+			),
+			array(
+				"<Hello \n World>",
+				"<Hello   World>",
+			),
+			array(
+				"<!-- Hello \n World -->",
+				"<!-- Hello   World -->",
+			),
+			array(
+				"<!-- Hello <\n> World -->",
+				"<!-- Hello < > World -->",
+			),
+		);
+	}
+}
+?>
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