Test examples from RFC 7529

src/icalendar/cal.py

@@ -275,23 +275,29 @@ class Component(CaselessDict):
         """
         self.subcomponents.append(component)
 
-    def _walk(self, name):
+    def _walk(self, name, select):
         """Walk to given component.
         """
         result = []
-        if name is None or self.name == name:
+        if (name is None or self.name == name) and select(self):
             result.append(self)
         for subcomponent in self.subcomponents:
-            result += subcomponent._walk(name)
+            result += subcomponent._walk(name, select)
         return result
 
-    def walk(self, name=None):
+    def walk(self, name=None, select=lambda c: True):
         """Recursively traverses component and subcomponents. Returns sequence
         of same. If name is passed, only components with name will be returned.
+
+        :param name: The name of the component or None such as ``VEVENT``.
+        :param select: A function that takes the component as first argument
+          and returns True/False.
+        :returns: A list of components that match.
+        :rtype: list[Component]
         """
         if name is not None:
             name = name.upper()
-        return self._walk(name)
+        return self._walk(name, select)
 
     #####################
     # Generation

src/icalendar/tests/calendars/rfc_7529.ics

@@ -0,0 +1,29 @@
+BEGIN:VCALENDAR
+VERSION:2.0
+PRODID://RESEARCH IN MOTION//BIS 3.0
+METHOD:REQUEST
+BEGIN:VEVENT
+UID:4.3.1
+DTSTART;VALUE=DATE:20130210
+RRULE:RSCALE=CHINESE;FREQ=YEARLY
+SUMMARY:Chinese New Year
+END:VEVENT
+BEGIN:VEVENT
+UID:4.3.2
+DTSTART;VALUE=DATE:20130906
+RRULE:RSCALE=ETHIOPIC;FREQ=MONTHLY;BYMONTH=13
+SUMMARY:First day of 13th month
+END:VEVENT
+BEGIN:VEVENT
+UID:4.3.3
+DTSTART;VALUE=DATE:20140208
+RRULE:RSCALE=HEBREW;FREQ=YEARLY;BYMONTH=5L;BYMONTHDAY=8;SKIP=FORWARD
+SUMMARY:Anniversary
+END:VEVENT
+BEGIN:VEVENT
+UID:4.3.4
+DTSTART;VALUE=DATE:20120229
+RRULE:RSCALE=GREGORIAN;FREQ=YEARLY;SKIP=FORWARD
+SUMMARY:Anniversary
+END:VEVENT
+END:VCALENDAR

src/icalendar/tests/test_rfc_7529.py

@@ -0,0 +1,25 @@
+"""This tests the compatibility with RFC 7529.
+
+See
+- https://github.com/collective/icalendar/issues/653
+- https://www.rfc-editor.org/rfc/rfc7529.html
+"""
+import pytest
+
+
+@pytest.mark.parametrize(
+    "uid,scale",
+    [
+        ("4.3.1", "CHINESE"),
+        ("4.3.2", "ETHIOPIC"),
+        ("4.3.3", "HEBREW"),
+        ("4.3.4", "GREGORIAN"),
+    ]
+)
+def test_rscale(calendars, uid, scale):
+    """Check that the RSCALE is parsed correctly."""
+    event = calendars.rfc_7529.walk(select=lambda c: c.get("UID") == uid)[0]
+    print(event.errors)
+    rrule = event["RRULE"]
+    print(rrule)
+    assert rrule["RSCALE"] == [scale]