fix: safe-empty restock default so restock notification tokens work for any watch (#4249)

changedetectionio/notification_service.py

@@ -207,6 +207,10 @@ class NotificationContextData(dict):
             # Always the raw +/- diff regardless of LLM summary override (populated in handler.py from {{diff}})
             'raw_diff': FormattableDiff('', ''),
             'markup_text_links_to_html_links': False, # If automatic conversion of plaintext to HTML should happen
+            # Safe-empty default so restock tokens ({{ restock.price }} etc.) are a valid,
+            # non-crashing token for every watch. Restock watches override this via
+            # processors/restock_diff extra_notification_token_values().
+            'restock': {}, #@TODO ! should be fixed in a refactor of all processor types, maybe fetching a empty key returns null or even restock (or similar) should actually come from the JSON in the datadir processor-restock-diff.json etc
             'notification_timestamp': time.time(),
             'prev_snapshot': None,
             'preview_url': None,

changedetectionio/tests/test_notification_restock_token.py

@@ -0,0 +1,43 @@
+"""
+Regression tests for issue #3490 - "'restock' is undefined".
+
+A `{{ restock.price }}` token is accepted in a per-watch notification body (restock
+watches inject the value via processors/restock_diff extra_notification_token_values()),
+but the same token in a system-wide / non-restock context had no default. That made it:
+
+  1. crash rendering at send time for a non-restock watch (UndefinedError), and
+  2. fail save-time validation of a system-wide notification body (ValidationError),
+
+because `restock` was absent from NotificationContextData's default token set.
+
+These tests exercise the real send-time (jinja2_custom.render) and save-time
+(ValidateJinja2Template) code paths. They fail on a tree without the safe-empty
+default and pass with it.
+"""
+from changedetectionio.notification_service import NotificationContextData
+
+
+def test_restock_token_present_in_default_context():
+    assert 'restock' in NotificationContextData()
+
+
+def test_restock_token_renders_safely_for_non_restock_watch():
+    """Send time: a non-restock watch must not crash on {{ restock.price }}."""
+    from changedetectionio.jinja2_custom import render as jinja_render
+
+    ctx = NotificationContextData()  # a plain, non-restock watch context
+    rendered = jinja_render(template_str="Price is {{ restock.price }}", **ctx)
+    # The undefined price renders as empty rather than raising UndefinedError.
+    assert rendered == "Price is "
+
+
+def test_restock_token_validates_in_system_settings():
+    """Save time: a system-wide body using {{ restock.price }} must validate."""
+    from changedetectionio.forms import ValidateJinja2Template
+
+    class _Field:
+        def __init__(self, data):
+            self.data = data
+
+    # Raised ValidationError before the fix; must not raise now.
+    ValidateJinja2Template()(None, _Field("Price is {{ restock.price }}"))