Commit initial

tests/e2e/test_theme_toggle.py

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+"""UIE-04: E2E tests for theme toggle — data-theme cycling and localStorage persistence."""
+from __future__ import annotations
+import pytest
+
+
+def test_theme_cycles_on_click(page, live_server: str) -> None:
+    """Clicking theme button cycles data-theme attribute: auto -> light -> dark -> auto."""
+    page.goto(f"{live_server}/", wait_until="domcontentloaded")
+
+    # Initial state: auto (default from base.html)
+    initial_theme = page.evaluate("document.documentElement.getAttribute('data-theme')")
+    assert initial_theme == "auto"
+
+    # Click once -> light
+    page.click("button[aria-label='auto']")
+    page.wait_for_function(
+        "document.documentElement.getAttribute('data-theme') === 'light'",
+        timeout=2000,
+    )
+    assert page.evaluate("document.documentElement.getAttribute('data-theme')") == "light"
+
+    # Click again -> dark
+    page.click("button[aria-label='light']")
+    page.wait_for_function(
+        "document.documentElement.getAttribute('data-theme') === 'dark'",
+        timeout=2000,
+    )
+    assert page.evaluate("document.documentElement.getAttribute('data-theme')") == "dark"
+
+
+def test_theme_persists_across_reload(page, live_server: str) -> None:
+    """After clicking theme toggle, the chosen theme is restored on reload."""
+    page.goto(f"{live_server}/", wait_until="domcontentloaded")
+
+    # Switch to light mode
+    page.click("button[aria-label='auto']")
+    page.wait_for_function(
+        "document.documentElement.getAttribute('data-theme') === 'light'",
+        timeout=2000,
+    )
+
+    # Reload the page
+    page.reload(wait_until="domcontentloaded")
+
+    # Theme should still be light (from localStorage)
+    theme_after_reload = page.evaluate("document.documentElement.getAttribute('data-theme')")
+    assert theme_after_reload == "light"
+
+    # Cleanup: reset to auto
+    page.evaluate("localStorage.setItem('imptune_theme', 'auto')")