Add new AnsibleK8SModule class (#269)

* Add new AnsibleK8SModule class

This class is intended to replace part of the K8SAnsibleMixin class and
is part of a larger refactoring effort.

* Fix sanity errors

* Fix unit tests

* Add mock to test requirements

tests/unit/module_utils/test_core.py

@@ -0,0 +1,91 @@
+from __future__ import absolute_import, division, print_function
+
+__metaclass__ = type
+
+import json
+
+import kubernetes
+import pytest
+
+from ansible_collections.kubernetes.core.plugins.module_utils.k8s.core import (
+    AnsibleK8SModule,
+)
+
+MINIMAL_K8S_VERSION = "12.0.0"
+UNSUPPORTED_K8S_VERSION = "11.0.0"
+
+
+@pytest.mark.parametrize("stdin", [{}], indirect=["stdin"])
+def test_no_warn(monkeypatch, stdin, capfd):
+    monkeypatch.setattr(kubernetes, "__version__", MINIMAL_K8S_VERSION)
+
+    module = AnsibleK8SModule(argument_spec={})
+    with pytest.raises(SystemExit):
+        module.exit_json()
+    out, err = capfd.readouterr()
+
+    return_value = json.loads(out)
+
+    assert return_value.get("exception") is None
+    assert return_value.get("warnings") is None
+    assert return_value.get("failed") is None
+
+
+@pytest.mark.parametrize("stdin", [{}], indirect=["stdin"])
+def test_warn_on_k8s_version(monkeypatch, stdin, capfd):
+    monkeypatch.setattr(kubernetes, "__version__", UNSUPPORTED_K8S_VERSION)
+
+    module = AnsibleK8SModule(argument_spec={})
+    with pytest.raises(SystemExit):
+        module.exit_json()
+    out, err = capfd.readouterr()
+
+    return_value = json.loads(out)
+
+    assert return_value.get("warnings") is not None
+    warnings = return_value["warnings"]
+    assert len(warnings) == 1
+    assert "kubernetes" in warnings[0]
+    assert MINIMAL_K8S_VERSION in warnings[0]
+
+
+dependencies = [
+    ["18.20.0", "12.0.1", False],
+    ["18.20.0", "18.20.0", True],
+    ["12.0.1", "18.20.0", True],
+]
+
+
+@pytest.mark.parametrize(
+    "stdin,desired,actual,result", [({}, *d) for d in dependencies], indirect=["stdin"]
+)
+def test_has_at_least(monkeypatch, stdin, desired, actual, result, capfd):
+    monkeypatch.setattr(kubernetes, "__version__", actual)
+
+    module = AnsibleK8SModule(argument_spec={})
+
+    assert module.has_at_least("kubernetes", desired) is result
+
+
+dependencies = [
+    ["kubernetes", "18.20.0", "(kubernetes>=18.20.0)"],
+    ["foobar", "1.0.0", "(foobar>=1.0.0)"],
+    ["foobar", None, "(foobar)"],
+]
+
+
+@pytest.mark.parametrize(
+    "stdin,dependency,version,msg", [({}, *d) for d in dependencies], indirect=["stdin"]
+)
+def test_requires_fails_with_message(
+    monkeypatch, stdin, dependency, version, msg, capfd
+):
+    monkeypatch.setattr(kubernetes, "__version__", "12.0.0")
+    module = AnsibleK8SModule(argument_spec={})
+    with pytest.raises(SystemExit):
+        module.requires(dependency, version)
+    out, err = capfd.readouterr()
+    return_value = json.loads(out)
+
+    assert return_value.get("failed")
+    assert msg in return_value.get("msg")