8th day of python challenges 111-117

venv/lib/python3.6/site-packages/pandas/tests/util/test_move.py

@@ -0,0 +1,44 @@
+import pytest
+
+from pandas.util._move import BadMove, move_into_mutable_buffer, stolenbuf
+
+
+def test_cannot_create_instance_of_stolen_buffer():
+    # Stolen buffers need to be created through the smart constructor
+    # "move_into_mutable_buffer," which has a bunch of checks in it.
+
+    msg = "cannot create 'pandas.util._move.stolenbuf' instances"
+    with pytest.raises(TypeError, match=msg):
+        stolenbuf()
+
+
+def test_more_than_one_ref():
+    # Test case for when we try to use "move_into_mutable_buffer"
+    # when the object being moved has other references.
+
+    b = b"testing"
+
+    with pytest.raises(BadMove, match="testing") as e:
+
+        def handle_success(type_, value, tb):
+            assert value.args[0] is b
+            return type(e).handle_success(e, type_, value, tb)  # super
+
+        e.handle_success = handle_success
+        move_into_mutable_buffer(b)
+
+
+def test_exactly_one_ref():
+    # Test case for when the object being moved has exactly one reference.
+
+    b = b"testing"
+
+    # We need to pass an expression on the stack to ensure that there are
+    # not extra references hanging around. We cannot rewrite this test as
+    #   buf = b[:-3]
+    #   as_stolen_buf = move_into_mutable_buffer(buf)
+    # because then we would have more than one reference to buf.
+    as_stolen_buf = move_into_mutable_buffer(b[:-3])
+
+    # Materialize as byte-array to show that it is mutable.
+    assert bytearray(as_stolen_buf) == b"test"