Fix Annotation.__init__ to handle length-zero Sequence, fixes #290

src/crowsetta/annotation.py

@@ -88,15 +88,15 @@ def __init__(
         if seq is not None and bboxes is not None:
             raise ValueError("an Annotation can have either a ``seq``" "or ``bboxes``, but not both.")
 
-        if seq:
+        if seq is not None:
             if not (
                 isinstance(seq, crowsetta.Sequence)
                 or (isinstance(seq, list) and all([isinstance(seq_, crowsetta.Sequence) for seq_ in seq]))
             ):
                 raise TypeError(f"``seq`` should be a crowsetta.Sequence or list of Sequences but was: {type(seq)}")
             self.seq = seq
 
-        if bboxes:
+        if bboxes is not None:
             if not isinstance(bboxes, list):
                 raise ValueError("``bboxes`` should be a list")
             if not all([isinstance(bbox, BBox) for bbox in bboxes]):

tests/test_annotation.py

@@ -70,3 +70,16 @@ def bbox_not_list_raises():
 def bbox_not_list_of_bboxes_raises():
     with pytest.raises(ValueError):
         crowsetta.Annotation(annot_path="./an/annnot.csv", notated_path=None, bboxes=[_ for _ in range(10)])
+
+
+def test_seq_with_no_segments():
+    """Test that an :class:`crowsetta.Annotation`
+    instantiated with a :class:`crowsetta.Sequence` 
+    that has no segments / a length of zero 
+    has a `seq` attribute that points to that Sequence.
+    """
+    # see https://github.com/vocalpy/crowsetta/issues/290
+    seq = crowsetta.Sequence.from_keyword(labels=[], onsets_s=[], offsets_s=[])
+    annot = crowsetta.Annotation(seq=seq, annot_path="./path.csv")
+    assert hasattr(annot, "seq")
+    assert annot.seq == seq