raise RuntimeError if writing with library version is too early, closes #273

We still raise a LibraryNotFoundError if there's no library at all

glymur/jp2k.py

@@ -415,10 +415,12 @@ class Jp2k(Jp2kBox):
         glymur.jp2k.LibraryNotFoundError
             if glymur is unable to load an openjpeg library suitable for writing
         """
+        if re.match("1.[0-4]", version.openjpeg_version) is not None:
+            raise RuntimeError("You must have at least version 1.5 of OpenJPEG "
+                               "in order to write images.")
+
         if opj2.OPENJP2 is None and opj.OPENJPEG is None:
-            raise LibraryNotFoundError("You must have at least version 1.5 of "
+            raise LibraryNotFoundError("Cannot load the OpenJPEG library.")
-                                       "OpenJPEG before using this "
-                                       "functionality.")
 
         self._determine_colorspace(img_array, **kwargs)
         cparams = self._populate_cparams(img_array, **kwargs)

glymur/test/test_jp2k.py

@@ -22,6 +22,11 @@ import uuid
 import warnings
 from xml.etree import cElementTree as ET
 
+if sys.hexversion <= 0x03030000:
+    from mock import patch
+else:
+    from unittest.mock import patch
+
 import numpy as np
 import pkg_resources
 
@@ -833,6 +838,17 @@ class TestJp2k_write(unittest.TestCase):
     def tearDown(self):
         pass
 
+    def test_write_with_version_too_early(self):
+        """Should raise a runtime error if trying to write with version 1.3"""
+        data = np.zeros((128, 128), dtype=np.uint8)
+        versions = ["1.0.0", "1.1.0", "1.2.0", "1.3.0"]
+        for version in versions:
+            with patch('glymur.version.openjpeg_version', new=version):
+                with tempfile.NamedTemporaryFile(suffix='.j2k') as tfile:
+                    with self.assertRaises(RuntimeError):
+                        j = Jp2k(tfile.name, 'wb')
+                        j.write(data)
+
     def test_cblkh_different_than_width(self):
         """Verify that we can set a code block size where height does not equal
         width.