Test Array storing different compressors, endian and attributes (#405)

* Test correct handling of endian data

Try storing data as both big endian and little endian. Ensure that the
data stored remains equal regardless of the stored endian order.

* Test store's handling of Array attributes

Make sure that the JSON contains the keys added to the Array attributes.

* Add test of multiple compressors with Arrays

Author: jakirkham

zarr/tests/test_core.py

@@ -3,6 +3,7 @@
 import unittest
 from tempfile import mkdtemp, mktemp
 import atexit
+import json
 import shutil
 import pickle
 import os
@@ -20,8 +21,9 @@
 from zarr.core import Array
 from zarr.errors import PermissionError
 from zarr.compat import PY2, text_type, binary_type, zip_longest
+from zarr.meta import ensure_str
 from zarr.util import buffer_size
-from numcodecs import (Delta, FixedScaleOffset, Zlib, Blosc, BZ2, MsgPack, Pickle,
+from numcodecs import (Delta, FixedScaleOffset, LZ4, GZip, Zlib, Blosc, BZ2, MsgPack, Pickle,
                        Categorize, JSON, VLenUTF8, VLenBytes, VLenArray)
 from numcodecs.compat import ensure_bytes, ensure_ndarray
 from numcodecs.tests.common import greetings
@@ -1215,6 +1217,39 @@ def test_iter(self):
             for expect, actual in zip_longest(a, z):
                 assert_array_equal(expect, actual)
 
+    def test_compressors(self):
+        compressors = [
+            None, BZ2(), Blosc(), LZ4(), Zlib(), GZip()
+        ]
+        if LZMA:
+            compressors.append(LZMA())
+        for compressor in compressors:
+            a = self.create_array(shape=1000, chunks=100, compressor=compressor)
+            a[0:100] = 1
+            assert np.all(a[0:100] == 1)
+            a[:] = 1
+            assert np.all(a[:] == 1)
+
+    def test_endian(self):
+        dtype = np.dtype('float32')
+        a1 = self.create_array(shape=1000, chunks=100, dtype=dtype.newbyteorder('<'))
+        a1[:] = 1
+        x1 = a1[:]
+        a2 = self.create_array(shape=1000, chunks=100, dtype=dtype.newbyteorder('>'))
+        a2[:] = 1
+        x2 = a2[:]
+        assert_array_equal(x1, x2)
+
+    def test_attributes(self):
+        a = self.create_array(shape=10, chunks=10, dtype='i8')
+        a.attrs['foo'] = 'bar'
+        attrs = json.loads(ensure_str(a.store[a.attrs.key]))
+        assert 'foo' in attrs and attrs['foo'] == 'bar'
+        a.attrs['bar'] = 'foo'
+        attrs = json.loads(ensure_str(a.store[a.attrs.key]))
+        assert 'foo' in attrs and attrs['foo'] == 'bar'
+        assert 'bar' in attrs and attrs['bar'] == 'foo'
+
 
 class TestArrayWithPath(TestArray):