fix several tests related to constants

I've added some tests that test regressions in the tests.

I've also made the message to include the number of times a certain
   message is missing or extra. Without it, I had a very confusing
   experience, when I seemed to have the message and yet the
   test-suite reported that I don't. Turned out, I had to add four
   more of the same!

Author: temyurchenko

pylint/testutils/lint_module_test.py

@@ -267,10 +267,16 @@ def error_msg_for_unequal_messages(
         )
         if missing:
             msg.append("\nExpected in testdata:")
-            msg.extend(f" {msg[0]:3}: {msg[1]}" for msg in sorted(missing))
+            msg.extend(
+                f" {msg[0]:3}: {msg[1]} (times {times})"
+                for msg, times in sorted(missing.items())
+            )
         if unexpected:
             msg.append("\nUnexpected in testdata:")
-            msg.extend(f" {msg[0]:3}: {msg[1]}" for msg in sorted(unexpected))
+            msg.extend(
+                f" {msg[0]:3}: {msg[1]} (times {times})"
+                for msg, times in sorted(unexpected.items())
+            )
         error_msg = "\n".join(msg)
         if self._config and self._config.getoption("verbose") > 0:
             error_msg += "\n\nActual pylint output for this file:\n"

tests/checkers/unittest_variables.py

@@ -22,7 +22,7 @@ class TestVariablesChecker(CheckerTestCase):
 
     def test_all_elements_without_parent(self) -> None:
         node = astroid.extract_node("__all__ = []")
-        node.value.elts.append(astroid.Const("test"))
+        node.value.elts.append(astroid.Const("test", parent=None))
         root = node.root()
         with self.assertNoMessages():
             self.checker.visit_module(root)

tests/functional/i/invalid/invalid_all/invalid_all_format_list_confusion.py

@@ -0,0 +1,5 @@
+# [line-too-long, missing-module-docstring, undefined-all-variable, undefined-all-variable, undefined-all-variable, undefined-all-variable, undefined-all-variable]
+# ↓ equivalent to __all__ = ["C", "O", "N", "S", "T"]
+__all__ = list("CONST")
+#
+CONST = 42

tests/functional/i/invalid/invalid_all/invalid_all_format_list_confusion.txt

@@ -0,0 +1,7 @@
+line-too-long:1:0:None:None::Line too long (163/100):UNDEFINED
+missing-module-docstring:1:0:None:None::Missing module docstring:HIGH
+undefined-all-variable:1:0:None:None::Undefined variable name 'C' in __all__:UNDEFINED
+undefined-all-variable:1:0:None:None::Undefined variable name 'N' in __all__:UNDEFINED
+undefined-all-variable:1:0:None:None::Undefined variable name 'O' in __all__:UNDEFINED
+undefined-all-variable:1:0:None:None::Undefined variable name 'S' in __all__:UNDEFINED
+undefined-all-variable:1:0:None:None::Undefined variable name 'T' in __all__:UNDEFINED

tests/functional/i/invalid/invalid_all/invalid_all_format_tuple_confusion.py

@@ -0,0 +1,5 @@
+# [line-too-long, missing-module-docstring, undefined-all-variable, undefined-all-variable, undefined-all-variable, undefined-all-variable, undefined-all-variable]
+# ↓ equivalent to __all__ = ("C", "O", "N", "S", "T")
+__all__ = tuple("CONST")
+
+CONST = 42

tests/functional/i/invalid/invalid_all/invalid_all_format_tuple_confusion.txt

@@ -0,0 +1,7 @@
+line-too-long:1:0:None:None::Line too long (163/100):UNDEFINED
+missing-module-docstring:1:0:None:None::Missing module docstring:HIGH
+undefined-all-variable:1:0:None:None::Undefined variable name 'C' in __all__:UNDEFINED
+undefined-all-variable:1:0:None:None::Undefined variable name 'N' in __all__:UNDEFINED
+undefined-all-variable:1:0:None:None::Undefined variable name 'O' in __all__:UNDEFINED
+undefined-all-variable:1:0:None:None::Undefined variable name 'S' in __all__:UNDEFINED
+undefined-all-variable:1:0:None:None::Undefined variable name 'T' in __all__:UNDEFINED

tests/functional/i/invalid/invalid_all/invalid_all_format_valid_3.py

@@ -1,4 +1,5 @@
 """Test valid __all__ format."""
-__all__ = list("CONST")
+
+__all__ = list(["CONST"])
 
 CONST = 42

tests/functional/i/invalid/invalid_all/invalid_all_format_valid_4.py

@@ -1,4 +1,5 @@
 """Test valid __all__ format."""
-__all__ = tuple("CONST")
+
+__all__ = tuple(["CONST"])
 
 CONST = 42