--- /dev/null
+<?php
+
+namespace MediaWiki\Session;
+
+use MediaWikiTestCase;
+
+/**
+ * @group Session
+ * @covers MediaWiki\Session\SessionId
+ */
+class SessionIdTest extends MediaWikiTestCase {
+
+ public function testEverything() {
+ $id = new SessionId( 'foo' );
+ $this->assertSame( 'foo', $id->getId() );
+ $this->assertSame( 'foo', (string)$id );
+ $id->setId( 'bar' );
+ $this->assertSame( 'bar', $id->getId() );
+ $this->assertSame( 'bar', (string)$id );
+ }
+
+}