bmk: add Bookmarks.next_id

scanny · scanny · commit 4b4647330824 · 2019-09-02T18:41:09.000-07:00
diff --git a/docx/bookmark.py b/docx/bookmark.py
@@ -46,11 +46,6 @@ def __iter__(self):
     def __len__(self):
         return len(self._finder.bookmark_pairs)
 
-    @lazyproperty
-    def _finder(self):
-        """_DocumentBookmarkFinder instance for this document."""
-        return _DocumentBookmarkFinder(self._document_part)
-
     def get(self, name):
         """Get bookmark based on its name.
 
@@ -64,7 +59,15 @@ def get(self, name):
     @property
     def next_id(self):
         """Return the next available int bookmark-id, unique in document-wide scope."""
-        raise NotImplementedError
+        bookmark_ids = tuple(bookmark.id for bookmark in self)
+        if not bookmark_ids:
+            return 1
+        return max(bookmark_ids) + 1
+
+    @lazyproperty
+    def _finder(self):
+        """_DocumentBookmarkFinder instance for this document."""
+        return _DocumentBookmarkFinder(self._document_part)
 
 
 class _Bookmark(object):
diff --git a/features/doc-document.feature b/features/doc-document.feature
@@ -1,9 +1,8 @@
 Feature: Document properties and methods
-  In order manipulate a Word document
+  In order to manipulate a Word document
   As a developer using python-docx
   I need properties and methods on the Document object
 
-  @wip
   Scenario: Document.start_bookmark()
     Given a Document object as document
      When I assign bookmark = document.start_bookmark("Target")
diff --git a/tests/test_bookmark.py b/tests/test_bookmark.py
@@ -121,6 +121,15 @@ def but_it_raises_KeyError_when_no_bookmark_by_that_name(self, bookmark_, _iter_
             bookmarks.get("barfoo")
         assert e.value.args[0] == "Requested bookmark not found."
 
+    def it_knows_the_next_available_bookmark_id(self, next_id_fixture, _iter_):
+        mock_bookmarks, expected_value = next_id_fixture
+        _iter_.return_value = iter(mock_bookmarks)
+        bookmarks = Bookmarks(None)
+
+        next_id = bookmarks.next_id
+
+        assert next_id is expected_value
+
     def it_provides_access_to_its_bookmark_finder_to_help(
         self, document_part_, _DocumentBookmarkFinder_, finder_
     ):
@@ -151,6 +160,14 @@ def contains_fixture(self, request):
             bookmark_.name = member_names[idx]
         return mock_bookmarks, name, expected_value
 
+    @pytest.fixture(params=[((), 1), ((1, 2, 3), 4), ((1, 3), 4), ((2, 42), 43)])
+    def next_id_fixture(self, request):
+        bookmark_ids, expected_value = request.param
+        mock_bookmarks = tuple(
+            instance_mock(request, _Bookmark, id=bmid) for bmid in bookmark_ids
+        )
+        return mock_bookmarks, expected_value
+
     # fixture components ---------------------------------------------
 
     @pytest.fixture
