diff --git a/tests/phpunit/tests/comment/commentExcerpt.php b/tests/phpunit/tests/comment/commentExcerpt.php
new file mode 100644
index 0000000000000..6f4142e495ec6
--- /dev/null
+++ b/tests/phpunit/tests/comment/commentExcerpt.php
@@ -0,0 +1,82 @@
+<?php
+
+/**
+ * Tests for comment_excerpt().
+ *
+ * @group comment
+ *
+ * @covers ::comment_excerpt
+ * @covers ::get_comment_excerpt
+ */
+class Tests_Comment_CommentExcerpt extends WP_UnitTestCase {
+
+	/**
+	 * Post fixture.
+	 *
+	 * @var int
+	 */
+	private static $post_id;
+
+	/**
+	 * Comment fixture.
+	 *
+	 * @var WP_Comment
+	 */
+	private static $comment;
+
+	public static function wpSetUpBeforeClass( WP_UnitTest_Factory $factory ) {
+		self::$post_id = $factory->post->create();
+		self::$comment = $factory->comment->create_and_get(
+			array(
+				'comment_post_ID' => self::$post_id,
+				'comment_content' => 'Short comment excerpt text.',
+			)
+		);
+	}
+
+	public function tear_down() {
+		unset( $GLOBALS['comment'] );
+		parent::tear_down();
+	}
+
+	/**
+	 * @ticket 65819
+	 */
+	public function test_comment_excerpt_echoes_excerpt() {
+		$this->expectOutputString( 'Short comment excerpt text.' );
+		comment_excerpt( self::$comment->comment_ID );
+	}
+
+	/**
+	 * @ticket 65819
+	 */
+	public function test_comment_excerpt_accepts_comment_object() {
+		$this->expectOutputString( 'Short comment excerpt text.' );
+		comment_excerpt( self::$comment );
+	}
+
+	/**
+	 * @ticket 65819
+	 */
+	public function test_comment_excerpt_uses_global_comment_when_unspecified() {
+		$GLOBALS['comment'] = self::$comment;
+
+		$this->expectOutputString( 'Short comment excerpt text.' );
+		comment_excerpt();
+	}
+
+	/**
+	 * @ticket 65819
+	 */
+	public function test_comment_excerpt_filter_can_modify_output() {
+		add_filter(
+			'comment_excerpt',
+			static function () {
+				return 'Filtered excerpt.';
+			}
+		);
+
+		$this->expectOutputString( 'Filtered excerpt.' );
+		comment_excerpt( self::$comment->comment_ID );
+	}
+}