Added negative test for writing with bad approximation. #202

glymur/jp2k.py

@@ -1250,6 +1250,7 @@ def _validate_jp2_box_sequence(boxes):
     if boxes[1].brand == 'jpx ':
         _validate_jpx_box_sequence(boxes)
     else:
+        # Validate the JP2 box IDs.
         count = _collect_box_count(boxes)
         for box_id in count.keys():
             if box_id not in JP2_IDS:
@@ -1257,6 +1258,19 @@ def _validate_jp2_box_sequence(boxes):
                 msg += "brand be set to 'jpx '."
                 raise IOError(msg.format(box_id))
 
+        _validate_jp2_colr(boxes)
+
+def _validate_jp2_colr(boxes):
+    """
+    Validate JP2 requirements on colour specification boxes.
+    """
+    lst = [box for box in boxes if box.box_id == 'jp2h']
+    jp2h = lst[0]
+    for colr in [box for box in jp2h.box if box.box_id == 'colr']:
+        if colr.approximation != 0:
+            msg = "A JP2 colr box cannot have a non-zero approximation field."
+            raise IOError(msg)
+
 def _validate_jpx_box_sequence(boxes):
     """Run through series of tests for JPX box legality."""
     _validate_label(boxes)

glymur/test/test_jp2box.py

@@ -453,6 +453,18 @@ class TestColourSpecificationBox(unittest.TestCase):
             with self.assertRaises(IOError):
                 j2k.wrap(tfile.name, boxes=boxes)
 
+    @unittest.skipIf(os.name == "nt", "Temporary file issue on window.")
+    def test_bad_approx_jp2_field(self):
+        """JP2 has requirements for approx field"""
+        j2k = Jp2k(self.j2kfile)
+        boxes = [self.jp2b, self.ftyp, self.jp2h, self.jp2c]
+        colr = ColourSpecificationBox(colorspace=glymur.core.SRGB,
+                                      approximation=1)
+        boxes[2].box = [self.ihdr, colr]
+        with tempfile.NamedTemporaryFile(suffix=".jp2") as tfile:
+            with self.assertRaises(IOError):
+                j2k.wrap(tfile.name, boxes=boxes)
+
     def test_default_colr(self):
         """basic colr instantiation"""
         colr = ColourSpecificationBox(colorspace=glymur.core.SRGB)