Prefer unitest.mock by universally using compat.mock (#433)

* Prefer unitest.mock by using compat.mock

`mock` is a backport of the `unittest.mock` module from the stdlib, and
there's no reason to use it on newer Python versions. `mock` is deprecated
in Fedora, so I figured I'd propose this here before downstream patching
our ansible-collection-community-docker package.

* Remove compat.mock code for older Python 3 versions

This removes compatibility for older versions of Python 3 that are no
longer supported.

tests/unit/compat/mock.py

@@ -28,82 +28,3 @@ except ImportError:
         from mock import *
     except ImportError:
         print('You need the mock library installed on python2.x to run tests')
-
-
-# Prior to 3.4.4, mock_open cannot handle binary read_data
-if sys.version_info >= (3,) and sys.version_info < (3, 4, 4):
-    file_spec = None
-
-    def _iterate_read_data(read_data):
-        # Helper for mock_open:
-        # Retrieve lines from read_data via a generator so that separate calls to
-        # readline, read, and readlines are properly interleaved
-        sep = b'\n' if isinstance(read_data, bytes) else '\n'
-        data_as_list = [l + sep for l in read_data.split(sep)]
-
-        if data_as_list[-1] == sep:
-            # If the last line ended in a newline, the list comprehension will have an
-            # extra entry that's just a newline.  Remove this.
-            data_as_list = data_as_list[:-1]
-        else:
-            # If there wasn't an extra newline by itself, then the file being
-            # emulated doesn't have a newline to end the last line  remove the
-            # newline that our naive format() added
-            data_as_list[-1] = data_as_list[-1][:-1]
-
-        for line in data_as_list:
-            yield line
-
-    def mock_open(mock=None, read_data=''):
-        """
-        A helper function to create a mock to replace the use of `open`. It works
-        for `open` called directly or used as a context manager.
-
-        The `mock` argument is the mock object to configure. If `None` (the
-        default) then a `MagicMock` will be created for you, with the API limited
-        to methods or attributes available on standard file handles.
-
-        `read_data` is a string for the `read` methoddline`, and `readlines` of the
-        file handle to return.  This is an empty string by default.
-        """
-        def _readlines_side_effect(*args, **kwargs):
-            if handle.readlines.return_value is not None:
-                return handle.readlines.return_value
-            return list(_data)
-
-        def _read_side_effect(*args, **kwargs):
-            if handle.read.return_value is not None:
-                return handle.read.return_value
-            return type(read_data)().join(_data)
-
-        def _readline_side_effect():
-            if handle.readline.return_value is not None:
-                while True:
-                    yield handle.readline.return_value
-            for line in _data:
-                yield line
-
-        global file_spec
-        if file_spec is None:
-            import _io
-            file_spec = list(set(dir(_io.TextIOWrapper)).union(set(dir(_io.BytesIO))))
-
-        if mock is None:
-            mock = MagicMock(name='open', spec=open)
-
-        handle = MagicMock(spec=file_spec)
-        handle.__enter__.return_value = handle
-
-        _data = _iterate_read_data(read_data)
-
-        handle.write.return_value = None
-        handle.read.return_value = None
-        handle.readline.return_value = None
-        handle.readlines.return_value = None
-
-        handle.read.side_effect = _read_side_effect
-        handle.readline.side_effect = _readline_side_effect()
-        handle.readlines.side_effect = _readlines_side_effect
-
-        mock.return_value = handle
-        return mock

tests/unit/plugins/inventory/test_docker_containers.py

@@ -11,7 +11,7 @@ import textwrap
 
 import pytest
 
-from mock import MagicMock
+from ansible_collections.community.docker.tests.unit.compat.mock import MagicMock
 
 from ansible import constants as C
 from ansible.errors import AnsibleError