Add ArtificialND2 class to help in testing nd2 file reading and parsing

nd2reader/artificial.py

@@ -0,0 +1,47 @@
+"""
+Functions to create artificial nd2 data for testing purposes
+"""
+import six
+
+
+class ArtificialND2(object):
+    """
+    Artificial ND2 class (for testing purposes)
+    """
+
+    def __init__(self, file):
+        self._fh = open(file, 'wb')
+        self.write_version()
+
+    def __enter__(self):
+        return self
+
+    def __exit__(self, exc_type, exc_value, traceback):
+        self.close()
+
+    @property
+    def file_handle(self):
+        """
+        The file handle to the binary file
+        Returns:
+            file: the file handle
+        """
+        return self._fh
+
+    def close(self):
+        """
+        Correctly close the file handle
+        """
+        if self._fh is not None:
+            self._fh.close()
+
+    def write_version(self):
+        """
+        Write file header
+        """
+        # write 16 empty bytes
+        self._fh.write(bytearray(16))
+
+        # write version info
+        version_info = six.b('ND2 FILE SIGNATURE CHUNK NAME01!Ver3.0')
+        self._fh.write(version_info)

tests/test_common.py

@@ -1,10 +1,16 @@
 import unittest
-
+from os import path
 import six
-from nd2reader.common import parse_version, parse_date, _add_to_metadata
+
+from nd2reader.artificial import ArtificialND2
+from nd2reader.common import get_version, parse_version, parse_date, _add_to_metadata
 
 
 class TestCommon(unittest.TestCase):
+    def setUp(self):
+        dir_path = path.dirname(path.realpath(__file__))
+        self.test_file = path.join(dir_path, 'test_data/test.nd2')
+
     def test_parse_version_2(self):
         data = 'ND2 FILE SIGNATURE CHUNK NAME01!Ver2.2'
         actual = parse_version(data)
@@ -17,6 +23,14 @@ class TestCommon(unittest.TestCase):
         expected = (3, 0)
         self.assertTupleEqual(actual, expected)
 
+    def test_get_version_from_file(self):
+        with ArtificialND2(self.test_file) as artificial:
+            artificial.close()
+
+        with open(self.test_file, 'rb') as fh:
+            version_tuple = get_version(fh)
+            self.assertTupleEqual(version_tuple, (3, 0))
+
     def test_parse_date_24(self):
         date_format = "%m/%d/%Y  %H:%M:%S"
         date = '02/13/2016  23:43:37'
@@ -45,5 +59,3 @@ class TestCommon(unittest.TestCase):
         metadata = {'test': ['value1', 'value2']}
         _add_to_metadata(metadata, 'test', 'value3')
         self.assertDictEqual(metadata, {'test': ['value1', 'value2', 'value3']})
-
-