test: add comprehensive easter egg tests

Added tests to verify easter egg ticker is properly implemented:
- Script injected via Blocks head parameter (executes in browser)
- HTML/CSS in gr.HTML() component (no script tags)
- Event listener checks for 'e' key (both lowercase and uppercase)
- Guards against INPUT/TEXTAREA to prevent triggering while typing
- Retry logic for DOM element initialization
- Ticker toggles .active class for animation

Also fixed: removed extra triple-quote causing syntax error in app.py

hearthnet/ui/app.py

@@ -117,7 +117,6 @@ _EASTER_EGG_SCRIPT = """
 })();
 </script>
 """
-"""
 
 
 class UiApp:

tests/test_easter_egg.py

@@ -0,0 +1,67 @@
+"""Test easter egg functionality in Gradio UI."""
+
+from __future__ import annotations
+
+import re
+
+
+def test_easter_egg_implementation():
+    """Verify easter egg ticker is properly implemented in app.py.
+    
+    Tests that:
+    1. Script is injected via head parameter (not innerHTML)
+    2. HTML/CSS is in gr.HTML() component
+    3. Event listener checks for 'e' key
+    4. Guards against INPUT/TEXTAREA elements
+    """
+    from hearthnet.ui.app import _EASTER_EGG_SCRIPT, _EASTER_EGG_CSS
+    
+    # Verify CSS contains the ticker styling
+    assert ".egg-ticker" in _EASTER_EGG_CSS, "CSS missing .egg-ticker class"
+    assert ".egg-ticker.active" in _EASTER_EGG_CSS, "CSS missing .egg-ticker.active state"
+    assert "@keyframes scroll" in _EASTER_EGG_CSS, "CSS missing scroll animation"
+    
+    # Verify HTML contains the ticker element
+    assert 'id="egg-ticker"' in _EASTER_EGG_CSS, "HTML missing egg-ticker id"
+    assert "⚡ LIVE" in _EASTER_EGG_CSS, "HTML missing LIVE label"
+    assert 'id="egg-track"' in _EASTER_EGG_CSS, "HTML missing egg-track id"
+    
+    # Verify script is injected via head parameter (must contain <script> tag)
+    assert "<script>" in _EASTER_EGG_SCRIPT, "Script must be wrapped in <script> tag for head parameter"
+    assert "</script>" in _EASTER_EGG_SCRIPT, "Script must have closing </script> tag"
+    
+    # Verify keydown listener
+    assert "evt.key === 'e'" in _EASTER_EGG_SCRIPT, "Script missing 'e' key check (lowercase)"
+    assert "evt.key === 'E'" in _EASTER_EGG_SCRIPT, "Script missing 'E' key check (uppercase)"
+    
+    # Verify input guard
+    assert "'INPUT'" in _EASTER_EGG_SCRIPT, "Script missing INPUT guard"
+    assert "'TEXTAREA'" in _EASTER_EGG_SCRIPT, "Script missing TEXTAREA guard"
+    
+    # Verify toggle function
+    assert "toggleEasterEgg" in _EASTER_EGG_SCRIPT, "Script missing toggleEasterEgg function"
+    assert ".active" in _EASTER_EGG_SCRIPT, "Script not toggling .active class"
+    
+    # Verify retry logic for DOM element
+    assert "initEasterEgg" in _EASTER_EGG_SCRIPT, "Script missing initEasterEgg function"
+    assert "setTimeout(initEasterEgg" in _EASTER_EGG_SCRIPT, "Script missing retry logic for DOM"
+    
+    # Verify script is injected in Blocks head parameter
+    from hearthnet.ui.app import UiApp
+    import inspect
+    
+    build_code = inspect.getsource(UiApp.build)
+    assert "head=_EASTER_EGG_SCRIPT" in build_code, "Script not injected via head parameter in Blocks"
+    assert "gr.HTML(value=_EASTER_EGG_CSS)" in build_code, "CSS not injected via gr.HTML()"
+
+
+def test_easter_egg_no_script_in_html():
+    """Verify script is NOT embedded in gr.HTML() to avoid Gradio warning."""
+    from hearthnet.ui.app import _EASTER_EGG_CSS, _EASTER_EGG_SCRIPT
+    
+    # CSS should NOT contain script tags (they go to head parameter)
+    assert "<script>" not in _EASTER_EGG_CSS, "CSS component should not contain script (goes to head parameter)"
+    
+    # Script should be separate
+    assert len(_EASTER_EGG_SCRIPT) > 0, "Script must exist"
+    assert "<script>" in _EASTER_EGG_SCRIPT, "Script must be in _EASTER_EGG_SCRIPT constant"