Fix off by one, raise ValueError on closed file and set readable = Tr…

…ue (#69)

* raise Value Error on closed file
* fix off by one error
* update changelog

docs/changes.rst

@@ -1,5 +1,8 @@
 Changelog
 *********
+0.11.5
+======
+* Fix one off in open() method interfaces for azure backend
 
 0.11.4
 ======

simplekv/net/azurestore.py

@@ -142,16 +142,20 @@ def __init__(self, block_blob_service, container_name, key):
 
     def tell(self):
         """Returns he current offset as int. Always >= 0."""
+        if self.closed:
+            raise ValueError("I/O operation on closed file")
         return self.pos
 
     def read(self, size=-1):
         """Returns 'size' amount of bytes or less if there is no more data.
         If no size is given all data is returned. size can be >= 0."""
+        if self.closed:
+            raise ValueError("I/O operation on closed file")
         with map_azure_exceptions(key=self.key):
             if size < 0:
                 size = self.size - self.pos
 
-            end = min(self.pos + size - 1, self.size)
+            end = min(self.pos + size - 1, self.size - 1)
             if self.pos > end:
                 return b''
             b = self.block_blob_service.get_blob_to_bytes(
@@ -173,6 +177,8 @@ def seek(self, offset, whence=0):
         Any seek operation which moves the position after the stream
         should succeed. tell() should report that position and read()
         should return an empty bytes object."""
+        if self.closed:
+            raise ValueError("I/O operation on closed file")
         if whence == 0:
             if offset < 0:
                 raise IOError('seek would move position outside the file')
@@ -188,3 +194,6 @@ def seek(self, offset, whence=0):
 
     def seekable(self):
         return True
+
+    def readable(self):
+        return True

tests/test_azure_store.py

@@ -72,6 +72,7 @@ def test_open_seek_and_tell(self, store, key, long_value):
         store.put(key, long_value)
         ok = store.open(key)
         assert ok.seekable()
+        assert ok.readable()
         ok.seek(10)
         assert ok.tell() == 10
         ok.seek(-6, 1)
@@ -94,6 +95,14 @@ def test_open_seek_and_tell(self, store, key, long_value):
         assert ok.tell() == length_lv + 10
         assert b'' == ok.read()
 
+        ok.close()
+        with pytest.raises(ValueError):
+            ok.tell()
+        with pytest.raises(ValueError):
+            ok.read(1)
+        with pytest.raises(ValueError):
+            ok.seek(10)
+
 
 class TestExtendedKeysAzureStorage(TestAzureStorage, ExtendedKeyspaceTests):
     @pytest.fixture