Adds hash test for IO

Author: sobolevn

CHANGELOG.md

@@ -5,6 +5,10 @@ We follow Semantic Versions since the `0.1.0` release.
 
 ## 0.10.0 WIP
 
+### Features
+
+- Adds `__hash__` magic methods to all containers
+
 ### Misc
 
 - Updates `mypy` version

tests/test_io/test_io_equality.py

@@ -0,0 +1,19 @@
+# -*- coding: utf-8 -*-
+
+import pytest
+
+from returns.io import IO
+
+
+def test_equality():
+    """Ensures that containers can be compared."""
+    assert IO(1) == IO(1)
+    assert str(IO(1)) == '<IO: 1>'
+    assert hash(IO(1))
+
+
+def test_nonequality():
+    """Ensures that containers are not compared to regular values."""
+    assert IO(1) != 1
+    assert IO(1) is not IO(1)
+    assert IO(1) != IO(2)