diff --git a/src/mega/mega.py b/src/mega/mega.py
index 37ba3dd..f509f59 100644
--- a/src/mega/mega.py
+++ b/src/mega/mega.py
@@ -569,8 +569,8 @@ class Mega:
         Download a file by it's file object
         """
         self._download_file(
-            None,
-            None,
+            file_handle=None,
+            file_key=None,
             file=file[1],
             dest_path=dest_path,
             dest_filename=dest_filename,
@@ -647,7 +647,11 @@ class Mega:
         file_id = path[0]
         file_key = path[1]
         self._download_file(
-            file_id, file_key, dest_path, dest_filename, is_public=True
+            file_handle=file_id,
+            file_key=file_key,
+            dest_path=dest_path,
+            dest_filename=dest_filename,
+            is_public=True,
         )
 
     def _download_file(
diff --git a/src/tests/test_crypto.py b/src/tests/test_crypto.py
new file mode 100644
index 0000000..9b8cc77
--- /dev/null
+++ b/src/tests/test_crypto.py
@@ -0,0 +1,42 @@
+import pytest
+
+from mega.crypto import get_chunks
+
+
+@pytest.mark.parametrize(
+    'file_size, exp_result', [
+        (
+            10,
+            (
+                (0, 10),
+            )
+        ),
+        (
+            1000,
+            (
+                (0, 1000),
+            )
+        ),
+        (
+            1000000,
+            (
+                (0, 131072), (131072, 262144), (393216, 393216),
+                (786432, 213568)
+            )
+        ),
+        (
+            10000000,
+            (
+                (0, 131072), (131072, 262144), (393216, 393216),
+                (786432, 524288), (1310720, 655360), (1966080, 786432),
+                (2752512, 917504), (3670016, 1048576), (4718592, 1048576),
+                (5767168, 1048576), (6815744, 1048576), (7864320, 1048576),
+                (8912896, 1048576), (9961472, 38528)
+            )
+        ),
+    ]
+)
+def test_get_chunks(file_size, exp_result):
+    result = tuple(get_chunks(file_size))
+
+    assert result == exp_result
diff --git a/src/tests/tests.py b/src/tests/test_mega.py
similarity index 100%
rename from src/tests/tests.py
rename to src/tests/test_mega.py
diff --git a/tox.ini b/tox.ini
index fd4b4c3..52c8da7 100644
--- a/tox.ini
+++ b/tox.ini
@@ -6,7 +6,7 @@ commands =
     flake8 {toxinidir}/src/
     coverage erase
     python setup.py install
-    pytest {toxinidir}/src/tests/tests.py
+    pytest {toxinidir}/src/tests/
 passenv =
     EMAIL
     PASS