Add simple tests for adding a new file association.

Author: Ben Cipollini

nibabel/tests/test_openers.py

@@ -19,6 +19,7 @@
 
 from ..openers import Opener, ImageOpener
 
+from nose.case import Test
 from nose.tools import (assert_true, assert_false, assert_equal,
                         assert_not_equal, assert_raises)
 
@@ -84,13 +85,39 @@ def test_Opener_various():
                     # Just check there is a fileno
                     assert_not_equal(fobj.fileno(), 0)
 
-def test_ImageOpener():
-    # Test that ImageOpener does add '.mgz' as gzipped file type
-    with InTemporaryDirectory():
-        with ImageOpener('test.gz', 'w') as fobj:
-            assert_true(hasattr(fobj.fobj, 'compress'))
-        with ImageOpener('test.mgz', 'w') as fobj:
-            assert_true(hasattr(fobj.fobj, 'compress'))
+
+class TestImageOpener:
+    def setUp(self):
+        self.compress_ext_map = ImageOpener.compress_ext_map.copy()
+
+    def teardown(self):
+        ImageOpener.compress_ext_map = self.compress_ext_map
+
+    def test_vanilla(self):
+        # Test that ImageOpener does add '.mgz' as gzipped file type
+        with InTemporaryDirectory():
+            with ImageOpener('test.gz', 'w') as fobj:
+                assert_true(hasattr(fobj.fobj, 'compress'))
+            with ImageOpener('test.mgz', 'w') as fobj:
+                assert_true(hasattr(fobj.fobj, 'compress'))
+
+    def test_new_association(self):
+        def file_opener(fileish, mode):
+            return open(fileish, mode)
+
+        # Add the association
+        n_associations = len(ImageOpener.compress_ext_map)
+        dec = ImageOpener.register_ext_from_image('.foo',
+                                                  (file_opener, ('mode',)))
+        dec(self.__class__)
+        assert_equal(n_associations + 1, len(ImageOpener.compress_ext_map))
+        assert_true('.foo' in ImageOpener.compress_ext_map)
+
+        with InTemporaryDirectory():
+            with ImageOpener('test.foo', 'w'):
+                pass
+            assert_true(os.path.exists('test.foo'))
+
 
 def test_file_like_wrapper():
     # Test wrapper using BytesIO (full API)