1 files changed, 86 insertions, 0 deletions
diff --git a/src/ansiblelint/rules/literal_compare.py b/src/ansiblelint/rules/literal_compare.py
new file mode 100644
index 0000000..1129d1d
--- /dev/null
+++ b/src/ansiblelint/rules/literal_compare.py
@@ -0,0 +1,86 @@
+"""Implementation of the literal-compare rule."""
+# Copyright (c) 2016, Will Thames and contributors
+# Copyright (c) 2018-2021, Ansible Project
+
+from __future__ import annotations
+
+import re
+import sys
+from typing import TYPE_CHECKING
+
+from ansiblelint.rules import AnsibleLintRule
+from ansiblelint.yaml_utils import nested_items_path
+
+if TYPE_CHECKING:
+    from ansiblelint.file_utils import Lintable
+    from ansiblelint.utils import Task
+
+
+class ComparisonToLiteralBoolRule(AnsibleLintRule):
+    """Don't compare to literal True/False."""
+
+    id = "literal-compare"
+    description = (
+        "Use ``when: var`` rather than ``when: var == True`` "
+        "(or conversely ``when: not var``)"
+    )
+    severity = "HIGH"
+    tags = ["idiom"]
+    version_added = "v4.0.0"
+
+    literal_bool_compare = re.compile("[=!]= ?(True|true|False|false)")
+
+    def matchtask(
+        self,
+        task: Task,
+        file: Lintable | None = None,
+    ) -> bool | str:
+        for k, v, _ in nested_items_path(task):
+            if k == "when":
+                if isinstance(v, str):
+                    if self.literal_bool_compare.search(v):
+                        return True
+                elif isinstance(v, bool):
+                    pass
+                else:
+                    for item in v:
+                        if isinstance(item, str) and self.literal_bool_compare.search(
+                            item,
+                        ):
+                            return True
+
+        return False
+
+
+if "pytest" in sys.modules:
+    import pytest
+
+    from ansiblelint.rules import RulesCollection  # pylint: disable=ungrouped-imports
+    from ansiblelint.runner import Runner  # pylint: disable=ungrouped-imports
+
+    @pytest.mark.parametrize(
+        ("test_file", "failures"),
+        (
+            pytest.param(
+                "examples/playbooks/rule_literal_compare_fail.yml",
+                3,
+                id="fail",
+            ),
+            pytest.param(
+                "examples/playbooks/rule_literal_compare_pass.yml",
+                0,
+                id="pass",
+            ),
+        ),
+    )
+    def test_literal_compare(
+        default_rules_collection: RulesCollection,
+        test_file: str,
+        failures: int,
+    ) -> None:
+        """Test rule matches."""
+        # Enable checking of loop variable prefixes in roles
+        results = Runner(test_file, rules=default_rules_collection).run()
+        for result in results:
+            assert result.rule.id == "literal-compare"
+        assert len(results) == failures