Add Subsite theme as main theme; allow cascading of themes

code/extensions/SiteTreeSubsites.php

@@ -297,7 +297,7 @@ public static function contentcontrollerInit($controller)
         $subsite = Subsite::currentSubsite();
 
         if ($subsite && $subsite->Theme) {
-            Config::modify()->set(SSViewer::class, 'theme', Subsite::currentSubsite()->Theme);
+            SSViewer::set_themes(array_merge([$subsite->Theme], SSViewer::get_themes()));
         }
     }
 

tests/php/SiteTreeSubsitesTest.php

@@ -4,6 +4,7 @@
 
 use Page;
 use SilverStripe\CMS\Controllers\CMSMain;
+use SilverStripe\CMS\Controllers\ModelAsController;
 use SilverStripe\CMS\Model\ErrorPage;
 use SilverStripe\CMS\Model\SiteTree;
 use SilverStripe\Control\Director;
@@ -18,6 +19,7 @@
 use SilverStripe\Subsites\Model\Subsite;
 use SilverStripe\Subsites\Pages\SubsitesVirtualPage;
 use SilverStripe\Versioned\Versioned;
+use SilverStripe\View\SSViewer;
 
 class SiteTreeSubsitesTest extends BaseSubsiteTest
 {
@@ -337,6 +339,32 @@ public function testCopySubsiteWithoutChildren()
         $this->assertEquals($moved->SubsiteID, $newSubsite->ID, 'Ensure returned records are on new subsite');
         $this->assertEquals($moved->AllChildren()->count(), 0, 'All pages are copied across');
     }
+
+    /**
+     * @todo: move to a functional test?
+     */
+    public function testIfSubsiteThemeIsSetToThemeList()
+    {
+        $defaultThemes = ['default'];
+        SSViewer::set_themes($defaultThemes);
+
+        $subsitePage = $this->objFromFixture(Page::class, 'home');
+        Subsite::changeSubsite($subsitePage->SubsiteID);
+        $controller = ModelAsController::controller_for($subsitePage);
+        SiteTree::singleton()->extend('contentcontrollerInit', $controller);
+
+        $this->assertEquals(SSViewer::get_themes(), $defaultThemes,
+            'Themes should not be modified when Subsite has no theme defined');
+
+        $pageWithTheme = $this->objFromFixture(Page::class, 'subsite1_home');
+        Subsite::changeSubsite($pageWithTheme->SubsiteID);
+        $controller = ModelAsController::controller_for($pageWithTheme);
+        SiteTree::singleton()->extend('contentcontrollerInit', $controller);
+        $subsiteTheme = $pageWithTheme->Subsite()->Theme;
+        $this->assertEquals(SSViewer::get_themes(), array_merge([$subsiteTheme], $defaultThemes),
+            'Themes should be modified when Subsite has theme defined');
+
+    }
 }
 
 

tests/php/SubsiteFunctionalTest.php

@@ -0,0 +1,38 @@
+<?php
+
+namespace subsites\tests\php;
+
+
+use Page;
+use SilverStripe\Dev\FunctionalTest;
+use SilverStripe\Subsites\Model\Subsite;
+use SilverStripe\View\SSViewer;
+
+class SubsiteFunctionalTest extends FunctionalTest
+{
+    public static $fixture_file = 'subsites/tests/php/SubsiteTest.yml';
+
+    /**
+     * @todo: remove test from SiteTreeSubsitesTest when this one works. Seems domain lookup is broken atm
+     */
+    public function testIfSubsiteThemeIsSetToThemeList()
+    {
+        $this->markTestSkipped('doesn\'t work somehow - refactor when domain lookup is working');
+        $defaultThemes = ['default'];
+        SSViewer::set_themes($defaultThemes);
+
+        $subsitePage = $this->objFromFixture(Page::class, 'contact');
+        $this->get($subsitePage->AbsoluteLink());
+        $this->assertEquals($subsitePage->SubsiteID, Subsite::currentSubsiteID(), 'Subsite should be changed');
+        $this->assertEquals(SSViewer::get_themes(), $defaultThemes,
+            'Themes should not be modified when Subsite has no theme defined');
+
+        $pageWithTheme = $this->objFromFixture(Page::class, 'subsite1_contactus');
+        $this->get($pageWithTheme->AbsoluteLink());
+        $subsiteTheme = $pageWithTheme->Subsite()->Theme;
+        $this->assertEquals($pageWithTheme->SubsiteID, Subsite::currentSubsiteID(), 'Subsite should be changed');
+        $this->assertEquals(SSViewer::get_themes(), array_merge([$subsiteTheme], $defaultThemes),
+            'Themes should be modified when Subsite has theme defined');
+
+    }
+}

tests/php/SubsiteTest.yml

@@ -3,6 +3,7 @@ SilverStripe\Subsites\Model\Subsite:
     Title: Template
   subsite1:
     Title: Subsite1 Template
+    Theme: subsiteTheme
   subsite2:
     Title: Subsite2 Template
   domaintest1: