Fix when evaluation on Native Jinja and Python 3.10 (#75202)

* Fix when evaluation on Native Jinja and Python 3.10

* Add unit test

* Add explaining comment

* Enable jinja2_native before tests

Co-Authored-By: Matt Martz <matt@sivel.net>

* Sanity

* Return native template module instead of modifying globals

Co-authored-by: Matt Martz <matt@sivel.net>

3 files changed, 39 insertions, 9 deletions

diff --git a/changelogs/fragments/when-eval-native-py310.yml b/changelogs/fragments/when-eval-native-py310.yml
new file mode 100644
index 0000000000..f90b948add
--- /dev/null
+++ b/changelogs/fragments/when-eval-native-py310.yml
@@ -0,0 +1,2 @@
+bugfixes:
+  - Fix ``when`` evaluation on Native Jinja and Python 3.10.
diff --git a/lib/ansible/playbook/conditional.py b/lib/ansible/playbook/conditional.py
index 293013a281..7afcb41c06 100644
--- a/lib/ansible/playbook/conditional.py
+++ b/lib/ansible/playbook/conditional.py
@@ -28,7 +28,7 @@ from jinja2.exceptions import UndefinedError
 from ansible import constants as C
 from ansible.errors import AnsibleError, AnsibleUndefinedVariable
 from ansible.module_utils.six import text_type
-from ansible.module_utils._text import to_native
+from ansible.module_utils._text import to_native, to_text
 from ansible.playbook.attribute import FieldAttribute
 from ansible.utils.display import Display
 
@@ -181,8 +181,15 @@ class Conditional:
                 raise AnsibleError("Invalid conditional detected: %s" % to_native(e))
 
             # and finally we generate and template the presented string and look at the resulting string
+            # NOTE The spaces around True and False are intentional to short-circuit safe_eval and avoid
+            #      its expensive calls.
             presented = "{%% if %s %%} True {%% else %%} False {%% endif %%}" % conditional
-            val = templar.template(presented, disable_lookups=disable_lookups).strip()
+            # NOTE Convert the result to text to account for both native and non-native jinja.
+            # NOTE The templated result of `presented` is string on native jinja as well prior to Python 3.10.
+            #      ast.literal_eval on Python 3.10 removes leading whitespaces so " True " becomes bool True
+            #      as opposed to Python 3.9 and lower where the same would result in IndentationError and
+            #      string " True " would be returned by Templar.
+            val = to_text(templar.template(presented, disable_lookups=disable_lookups)).strip()
             if val == "True":
                 return True
             elif val == "False":
diff --git a/test/units/template/test_native_concat.py b/test/units/template/test_native_concat.py
index db85a73b92..4164bc4578 100644
--- a/test/units/template/test_native_concat.py
+++ b/test/units/template/test_native_concat.py
@@ -5,24 +5,45 @@
 from __future__ import (absolute_import, division, print_function)
 __metaclass__ = type
 
+import importlib
+import sys
+
 import pytest
 
 from ansible import constants as C
 from ansible.errors import AnsibleUndefinedVariable
-
-# need to mock DEFAULT_JINJA2_NATIVE here so native modules are imported
-# correctly within the template module
-C.DEFAULT_JINJA2_NATIVE = True
-from ansible.template import Templar
+from ansible.playbook.conditional import Conditional
 
 from units.mock.loader import DictDataLoader
 
 
+@pytest.fixture
+def native_template_mod(monkeypatch):
+    monkeypatch.delitem(sys.modules, 'ansible.template')
+    monkeypatch.setattr(C, 'DEFAULT_JINJA2_NATIVE', True)
+    return importlib.import_module('ansible.template')
+
+
 # https://github.com/ansible/ansible/issues/52158
-def test_undefined_variable():
+def test_undefined_variable(native_template_mod):
     fake_loader = DictDataLoader({})
     variables = {}
-    templar = Templar(loader=fake_loader, variables=variables)
+    templar = native_template_mod.Templar(loader=fake_loader, variables=variables)
+    assert isinstance(templar.environment, native_template_mod.AnsibleNativeEnvironment)
 
     with pytest.raises(AnsibleUndefinedVariable):
         templar.template("{{ missing }}")
+
+
+def test_cond_eval(native_template_mod):
+    fake_loader = DictDataLoader({})
+    # True must be stored in a variable to trigger templating. Using True
+    # directly would be caught by optimization for bools to short-circuit
+    # templating.
+    variables = {"foo": True}
+    templar = native_template_mod.Templar(loader=fake_loader, variables=variables)
+    assert isinstance(templar.environment, native_template_mod.AnsibleNativeEnvironment)
+
+    cond = Conditional(loader=fake_loader)
+    cond.when = ["foo"]
+    assert cond.evaluate_conditional(templar, variables)