Multisite: Use get_current_blog_id() in get_site() for current site.

The global `$current_blog` is not switched in `switch_to_blog()` and can
not be used to properly retrieve current switched site information.

See #37607.


git-svn-id: https://develop.svn.wordpress.org/trunk@38217 602fd350-edb4-49c9-b593-d223f7449a82

tests/phpunit/tests/multisite/getSite.php

@@ -0,0 +1,44 @@
+<?php
+
+if ( is_multisite() ) :
+/**
+ * Test get_site() wrapper of WP_Site in multisite.
+ *
+ * @group ms-site
+ * @group multisite
+ */
+class Tests_Multisite_Get_Site extends WP_UnitTestCase {
+	protected static $site_ids;
+
+	public static function wpSetUpBeforeClass( $factory ) {
+		self::$site_ids = array(
+			'wordpress.org/'              => array( 'domain' => 'wordpress.org',      'path' => '/' ),
+			'wordpress.org/foo/'          => array( 'domain' => 'wordpress.org',      'path' => '/foo/' ),
+			'wordpress.org/foo/bar/'      => array( 'domain' => 'wordpress.org',      'path' => '/foo/bar/' ),
+		);
+
+		foreach ( self::$site_ids as &$id ) {
+			$id = $factory->blog->create( $id );
+		}
+		unset( $id );
+	}
+
+	public static function wpTearDownAfterClass() {
+		foreach( self::$site_ids as $id ) {
+			wpmu_delete_blog( $id, true );
+		}
+
+		wp_update_network_site_counts();
+	}
+
+	public function test_get_site_in_switched_state_returns_switched_site() {
+		switch_to_blog( self::$site_ids[ 'wordpress.org/foo/' ] );
+		$site = get_site();
+		restore_current_blog();
+
+		$this->assertEquals( self::$site_ids[ 'wordpress.org/foo/'], $site->id );
+	}
+
+}
+
+endif;