[BUG] Include theme name in ThemedTemplateLoader cache key fallback

src/Twig/Loader/ThemedTemplateLoader.php

@@ -53,7 +53,14 @@ public function getCacheKey($name): string
         try {
             return $this->locateTemplate($name);
         } catch (TemplateNotFoundException $exception) {
-            return $this->decoratedLoader->getCacheKey($name);
+            $cacheKey = $this->decoratedLoader->getCacheKey($name);
+            $theme = $this->themeContext->getTheme();
+
+            if (null !== $theme) {
+                $cacheKey .= '|' . $theme->getName();
+            }
+
+            return $cacheKey;
         }
     }
 

tests/Twig/Loader/ThemedTemplateLoaderTest.php

@@ -0,0 +1,114 @@
+<?php
+
+/*
+ * This file is part of the Sylius package.
+ *
+ * (c) Sylius Sp. z o.o.
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+declare(strict_types=1);
+
+namespace Sylius\Bundle\ThemeBundle\Tests\Twig\Loader;
+
+use PHPUnit\Framework\TestCase;
+use Sylius\Bundle\ThemeBundle\Context\ThemeContextInterface;
+use Sylius\Bundle\ThemeBundle\Model\ThemeInterface;
+use Sylius\Bundle\ThemeBundle\Twig\Loader\ThemedTemplateLoader;
+use Sylius\Bundle\ThemeBundle\Twig\Locator\TemplateLocatorInterface;
+use Sylius\Bundle\ThemeBundle\Twig\Locator\TemplateNotFoundException;
+use Twig\Loader\LoaderInterface as TwigLoaderInterface;
+
+class ThemedTemplateLoaderTest extends TestCase
+{
+    /**
+     * @test
+     */
+    public function it_returns_located_path_as_cache_key_when_template_is_found_in_active_theme(): void
+    {
+        $decoratedLoader = $this->createMock(TwigLoaderInterface::class);
+        $templateLocator = $this->createMock(TemplateLocatorInterface::class);
+        $themeContext = $this->createMock(ThemeContextInterface::class);
+        $theme = $this->createMock(ThemeInterface::class);
+
+        $themeContext->method('getTheme')->willReturn($theme);
+        $templateLocator->method('locate')->willReturn('/path/to/theme-a/template.html.twig');
+
+        $loader = new ThemedTemplateLoader($decoratedLoader, $templateLocator, $themeContext);
+
+        $this->assertSame('/path/to/theme-a/template.html.twig', $loader->getCacheKey('template.html.twig'));
+    }
+
+    /**
+     * @test
+     */
+    public function it_appends_theme_name_to_cache_key_when_template_is_not_in_active_theme(): void
+    {
+        $decoratedLoader = $this->createMock(TwigLoaderInterface::class);
+        $templateLocator = $this->createMock(TemplateLocatorInterface::class);
+        $themeContext = $this->createMock(ThemeContextInterface::class);
+        $theme = $this->createMock(ThemeInterface::class);
+
+        $themeContext->method('getTheme')->willReturn($theme);
+        $theme->method('getName')->willReturn('sylius/theme-a');
+        $templateLocator->method('locate')->willThrowException(new TemplateNotFoundException('template.html.twig', []));
+        $decoratedLoader->method('getCacheKey')->willReturn('/path/to/templates/template.html.twig');
+
+        $loader = new ThemedTemplateLoader($decoratedLoader, $templateLocator, $themeContext);
+
+        $this->assertSame(
+            '/path/to/templates/template.html.twig|sylius/theme-a',
+            $loader->getCacheKey('template.html.twig'),
+        );
+    }
+
+    /**
+     * @test
+     */
+    public function it_returns_plain_cache_key_when_no_theme_is_active(): void
+    {
+        $decoratedLoader = $this->createMock(TwigLoaderInterface::class);
+        $templateLocator = $this->createMock(TemplateLocatorInterface::class);
+        $themeContext = $this->createMock(ThemeContextInterface::class);
+
+        $themeContext->method('getTheme')->willReturn(null);
+        $decoratedLoader->method('getCacheKey')->willReturn('/path/to/templates/template.html.twig');
+
+        $loader = new ThemedTemplateLoader($decoratedLoader, $templateLocator, $themeContext);
+
+        $this->assertSame(
+            '/path/to/templates/template.html.twig',
+            $loader->getCacheKey('template.html.twig'),
+        );
+    }
+
+    /**
+     * @test
+     */
+    public function it_returns_different_cache_keys_for_same_template_under_different_themes(): void
+    {
+        $decoratedLoader = $this->createMock(TwigLoaderInterface::class);
+        $templateLocator = $this->createMock(TemplateLocatorInterface::class);
+        $themeContext = $this->createMock(ThemeContextInterface::class);
+        $themeA = $this->createMock(ThemeInterface::class);
+        $themeB = $this->createMock(ThemeInterface::class);
+
+        $themeA->method('getName')->willReturn('sylius/theme-a');
+        $themeB->method('getName')->willReturn('sylius/theme-b');
+        $templateLocator->method('locate')->willThrowException(new TemplateNotFoundException('template.html.twig', []));
+        $decoratedLoader->method('getCacheKey')->willReturn('/path/to/templates/template.html.twig');
+
+        $themeContext->method('getTheme')->willReturnOnConsecutiveCalls($themeA, $themeA, $themeB, $themeB);
+
+        $loader = new ThemedTemplateLoader($decoratedLoader, $templateLocator, $themeContext);
+
+        $cacheKeyA = $loader->getCacheKey('template.html.twig');
+        $cacheKeyB = $loader->getCacheKey('template.html.twig');
+
+        $this->assertNotSame($cacheKeyA, $cacheKeyB);
+        $this->assertSame('/path/to/templates/template.html.twig|sylius/theme-a', $cacheKeyA);
+        $this->assertSame('/path/to/templates/template.html.twig|sylius/theme-b', $cacheKeyB);
+    }
+}