diff --git a/tests/phpunit/tests/formatting/linksAddBaseUrl.php b/tests/phpunit/tests/formatting/linksAddBaseUrl.php
new file mode 100644
index 0000000000000..0d88cc061a564
--- /dev/null
+++ b/tests/phpunit/tests/formatting/linksAddBaseUrl.php
@@ -0,0 +1,94 @@
+<?php
+
+/**
+ * Tests for the links_add_base_url function.
+ *
+ * @group formatting
+ *
+ * @covers ::links_add_base_url
+ */
+class Tests_formatting_linksAddBaseUrl extends WP_UnitTestCase {
+
+	/**
+	 * @ticket 60389
+	 *
+	 * @dataProvider data_links_add_base_url
+	 */
+	public function test_links_add_base_url( $content, $base, $attrs, $expected ) {
+		if ( $attrs ) {
+			$this->assertSame( $expected, links_add_base_url( $content, $base, $attrs ) );
+		} else {
+			$this->assertSame( $expected, links_add_base_url( $content, $base ) );
+		}
+	}
+
+	/**
+	 * Data provider for test_links_add_base_url().
+	 *
+	 * @return array[]
+	 */
+	public function data_links_add_base_url() {
+		return array(
+			'https'           => array(
+				'content'  => '<a href="url" />',
+				'base'     => 'https://localhost',
+				'attrs'    => null,
+				'expected' => '<a href="https://localhost/url" />',
+			),
+			'http'            => array(
+				'content'  => '<a href="url" />',
+				'base'     => 'http://localhost',
+				'attrs'    => null,
+				'expected' => '<a href="http://localhost/url" />',
+			),
+			'relative_scheme' => array(
+				'content'  => '<a href="//localhost/url" />',
+				'base'     => 'http://localhost',
+				'attrs'    => null,
+				'expected' => '<a href="http://localhost/url" />',
+			),
+			'empty_array'     => array(
+				'content'  => '<a href="url" target="_blank" />',
+				'base'     => 'https://localhost',
+				'attrs'    => array(),
+				'expected' => '<a href="https://localhost/url" target="_blank" />',
+			),
+			'data_url'        => array(
+				'content'  => '<a href="url" data-url="url" />',
+				'base'     => 'https://localhost',
+				'attrs'    => array( 'data-url', 'href' ),
+				'expected' => '<a href="https://localhost/url" data-url="https://localhost/url" />',
+			),
+			'not relative'    => array(
+				'content'  => '<a href="https://localhost/url" />',
+				'base'     => 'https://localbase',
+				'attrs'    => null,
+				'expected' => '<a href="https://localhost/url" />',
+			),
+			'no_href'         => array(
+				'content'  => '<a data-url="/url" />',
+				'base'     => 'https://localhost',
+				'attrs'    => null,
+				'expected' => '<a data-url="/url" />',
+			),
+			'img'             => array(
+				'content'  => '<img src="/url" />',
+				'base'     => 'https://localhost',
+				'attrs'    => null,
+				'expected' => '<img src="https://localhost/url" />',
+			),
+			'ftp'             => array(
+				'content'  => '<a href="/url" >sss</a>',
+				'base'     => 'ftp://localhost',
+				'attrs'    => null,
+				'expected' => '<a href="ftp://localhost/url" >sss</a>',
+			),
+			'ftps'            => array(
+				'content'  => '<a href="/url" >sss</a>',
+				'base'     => 'ftps://localhost',
+				'attrs'    => null,
+				'expected' => '<a href="ftps://localhost/url" >sss</a>',
+			),
+		);
+	}
+}