From 4e89412cde7facd5a0e9cb4f9dd673b7061e40a5 Mon Sep 17 00:00:00 2001
From: xfy <i@rua.plus>
Date: Mon, 15 Jun 2026 10:57:51 +0800
Subject: [PATCH] =?UTF-8?q?test(theme):=20=E6=89=A9=E5=85=85=E4=B8=BB?=
 =?UTF-8?q?=E9=A2=98=E6=A8=A1=E5=9D=97=E6=B5=8B=E8=AF=95=E8=A6=86=E7=9B=96?=
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原仅 2 个 toggle 测试，补充后覆盖：
- toggle 的对合性（连续切换两次回到原值）
- Theme 的 PartialEq / Copy trait 行为
- 首屏预加载脚本的关键行为契约：读取 localStorage、
  回退 prefers-color-scheme、添加 dark class、
  包裹 try/catch 防止禁用 localStorage 时抛错

共 9 个测试，全部通过。
---
 src/theme.rs | 51 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 51 insertions(+)

diff --git a/src/theme.rs b/src/theme.rs
index b1654a2..c34e40b 100644
--- a/src/theme.rs
+++ b/src/theme.rs
@@ -210,4 +210,55 @@ mod tests {
     fn toggle_switches_dark_to_light() {
         assert_eq!(Theme::Dark.toggle(), Theme::Light);
     }
+
+    #[test]
+    fn toggle_is_an_involution() {
+        // 连续切换两次应当回到原始主题。
+        assert_eq!(Theme::Light.toggle().toggle(), Theme::Light);
+        assert_eq!(Theme::Dark.toggle().toggle(), Theme::Dark);
+    }
+
+    #[test]
+    fn theme_derives_equality() {
+        // Theme 派生了 PartialEq，相同变体必须相等。
+        assert_eq!(Theme::Light, Theme::Light);
+        assert_eq!(Theme::Dark, Theme::Dark);
+        assert_ne!(Theme::Light, Theme::Dark);
+    }
+
+    #[test]
+    fn theme_is_copy() {
+        // 确认 Theme 实现了 Copy，赋值后原值仍可用。
+        let a = Theme::Light;
+        let b = a;
+        assert_eq!(a, b);
+        // 再次使用 a，若未实现 Copy 则编译失败。
+        let _ = a.toggle();
+    }
+
+    #[test]
+    fn theme_preload_script_adds_dark_class() {
+        // 预加载脚本必须包含给 documentElement 添加 dark class 的逻辑。
+        assert!(THEME_PRELOAD_SCRIPT.contains("classList.add('dark')"));
+    }
+
+    #[test]
+    fn theme_preload_script_reads_local_storage() {
+        // 预加载脚本必须读取 yggdrasil-theme 键，与 THEME_KEY 保持一致。
+        assert!(THEME_PRELOAD_SCRIPT.contains("localStorage.getItem('yggdrasil-theme')"));
+        assert_eq!(THEME_KEY, "yggdrasil-theme");
+    }
+
+    #[test]
+    fn theme_preload_script_falls_back_to_prefers_color_scheme() {
+        // 当 localStorage 中无主题时，脚本应回退到系统颜色偏好。
+        assert!(THEME_PRELOAD_SCRIPT.contains("prefers-color-scheme: dark"));
+    }
+
+    #[test]
+    fn theme_preload_script_swallows_errors() {
+        // 预加载脚本必须包裹在 try/catch 中，避免禁用 localStorage 时抛错。
+        assert!(THEME_PRELOAD_SCRIPT.contains("try"));
+        assert!(THEME_PRELOAD_SCRIPT.contains("catch"));
+    }
 }