Avoid same false positives with no-tabs rule (#1373)

As we identified some particular cases where use of tabs is perfectly
justified, we add exceptions for these.

Fixes: #1334

examples/playbooks/rule-no-tabs.yml

@@ -0,0 +1,10 @@
+- hosts: localhost
+  tasks:
+    - name: should not trigger no-tabs rules
+      lineinfile:
+        path: some.txt
+        regexp: '^\t$'
+        line: 'string with \t inside'
+    - name: foo
+      debug:
+        msg: "Presence of \t should trigger no-tabs here."

src/ansiblelint/rules/ComparisonToLiteralBoolRule.py

@@ -22,7 +22,7 @@ class ComparisonToLiteralBoolRule(AnsibleLintRule):
     literal_bool_compare = re.compile("[=!]= ?(True|true|False|false)")
 
     def matchtask(self, task: Dict[str, Any]) -> Union[bool, str]:
-        for k, v in nested_items(task):
+        for k, v, _ in nested_items(task):
             if k == 'when':
                 if isinstance(v, str):
                     if self.literal_bool_compare.search(v):

src/ansiblelint/rules/NoTabsRule.py

@@ -1,5 +1,6 @@
 # Copyright (c) 2016, Will Thames and contributors
 # Copyright (c) 2018, Ansible Project
+import sys
 from typing import Any, Dict, Union
 
 from ansiblelint.rules import AnsibleLintRule
@@ -13,11 +14,44 @@ class NoTabsRule(AnsibleLintRule):
     severity = 'LOW'
     tags = ['formatting']
     version_added = 'v4.0.0'
+    allow_list = [
+        ("lineinfile", "insertafter"),
+        ("lineinfile", "insertbefore"),
+        ("lineinfile", "regexp"),
+        ("lineinfile", "line"),
+    ]
 
     def matchtask(self, task: Dict[str, Any]) -> Union[bool, str]:
-        for k, v in nested_items(task):
+        for k, v, parent in nested_items(task):
             if isinstance(k, str) and '\t' in k:
                 return True
-            if isinstance(v, str) and '\t' in v:
+            if (parent, k) not in self.allow_list and isinstance(v, str) and '\t' in v:
                 return True
         return False
+
+
+RULE_EXAMPLE = r'''---
+- hosts: localhost
+  tasks:
+    - name: should not trigger no-tabs rules
+      lineinfile:
+        path: some.txt
+        regexp: '^\t$'
+        line: 'string with \t inside'
+    - name: foo
+      debug:
+        msg: "Presence of \t should trigger no-tabs here."
+'''
+
+# testing code to be loaded only with pytest or when executed the rule file
+if "pytest" in sys.modules:
+
+    import pytest
+
+    @pytest.mark.parametrize('rule_runner', (NoTabsRule,), indirect=['rule_runner'])
+    def test_no_tabs_rule(rule_runner: "Any") -> None:
+        """Test rule matches."""
+        results = rule_runner.run_playbook(RULE_EXAMPLE)
+        assert results[0].linenumber == 9
+        assert results[0].message == NoTabsRule.shortdesc
+        assert len(results) == 1

src/ansiblelint/rules/VariableHasSpacesRule.py

@@ -22,7 +22,7 @@ class VariableHasSpacesRule(AnsibleLintRule):
     exclude_json_re = re.compile(r"[^{]{'\w+': ?[^{]{.*?}}")
 
     def matchtask(self, task: Dict[str, Any]) -> Union[bool, str]:
-        for k, v in nested_items(task):
+        for k, v, _ in nested_items(task):
             if isinstance(v, str):
                 cleaned = self.exclude_json_re.sub("", v)
                 if bool(self.bracket_regex.search(cleaned)):

src/ansiblelint/utils.py

@@ -855,16 +855,16 @@ def convert_to_boolean(value: Any) -> bool:
 
 
 def nested_items(
-    data: Union[Dict[Any, Any], List[Any]]
-) -> Generator[Tuple[Any, Any], None, None]:
+    data: Union[Dict[Any, Any], List[Any]], parent: str = ""
+) -> Generator[Tuple[Any, Any, str], None, None]:
     """Iterate a nested data structure."""
     if isinstance(data, dict):
         for k, v in data.items():
-            yield k, v
-            for k, v in nested_items(v):
-                yield k, v
+            yield k, v, parent
+            for k, v, p in nested_items(v, k):
+                yield k, v, p
     if isinstance(data, list):
         for item in data:
-            yield "list-item", item
-            for k, v in nested_items(item):
-                yield k, v
+            yield "list-item", item, parent
+            for k, v, p in nested_items(item):
+                yield k, v, p

test/TestUtils.py

@@ -435,11 +435,11 @@ def test_nested_items():
     data = {"foo": "text", "bar": {"some": "text2"}, "fruits": ["apple", "orange"]}
 
     items = [
-        ("foo", "text"),
-        ("bar", {"some": "text2"}),
-        ("some", "text2"),
-        ("fruits", ["apple", "orange"]),
-        ("list-item", "apple"),
-        ("list-item", "orange"),
+        ("foo", "text", ""),
+        ("bar", {"some": "text2"}, ""),
+        ("some", "text2", "bar"),
+        ("fruits", ["apple", "orange"], ""),
+        ("list-item", "apple", "fruits"),
+        ("list-item", "orange", "fruits"),
     ]
     assert list(utils.nested_items(data)) == items