Add the ability to check two snapshots for each test

frontend/test/playwright/utils/theme-switcher.ts

@@ -0,0 +1,28 @@
+import { Page } from "@playwright/test"
+
+import { LanguageDirection, t } from "~~/test/playwright/utils/i18n"
+
+type EffectiveColorMode = "dark" | "light"
+const themeSelectLabel = (dir: LanguageDirection) => t("theme.theme", dir)
+const themeOption = (colorMode: EffectiveColorMode, dir: LanguageDirection) =>
+  t(`theme.choices.${colorMode}`, dir)
+
+export const setThemeSwitcherVisibility = async (
+  page: Page,
+  visibility: "visible" | "hidden"
+) => {
+  await page.evaluate((visibility) => {
+    const themeSwitcher = document.getElementById("storybook-theme-switcher")
+    if (themeSwitcher) {
+      themeSwitcher.style.visibility = visibility
+    }
+  }, visibility)
+}
+
+export const turnOnDarkMode = async (page: Page, dir: LanguageDirection) => {
+  await setThemeSwitcherVisibility(page, "visible")
+  await page
+    .getByLabel(themeSelectLabel(dir))
+    .selectOption(themeOption("dark", dir))
+  await setThemeSwitcherVisibility(page, "hidden")
+}