Is there a way to detect from within a LintRule if it's being run under test?

I'd like to be able to detect when a LintRule is being run under test. I know it's possible to use the FilePathProvider to detect if the filename is `valid.py` or `invalid.py` but that can lead to false positives. Here's a full example of a rule I'm [re]implementing below.

From within the rule, I want to check that we're linting an `__init__.py` file, so use the FilePathProvider to retrieve that information. Unfortunately unit tests will fail unless we also allow-through tests.

Is there a better way to detect if we're running under test?

```
import libcst.matchers as m
from fixit import LintRule
from libcst import Module, metadata
from tools.fixit.utils.general_utils import fixit_invalid, fixit_valid

CONVENIENCE_IMPORTS_OR_DOCSTRING = (
m.SimpleStatementLine(body=[m.Import()])
| m.SimpleStatementLine(body=[m.ImportFrom()])
| m.SimpleStatementLine(
body=[m.Assign(targets=[m.AssignTarget(target=m.Name(value="__all__"))])]
)
| m.SimpleStatementLine(body=[m.Expr(value=m.SimpleString() | m.ConcatenatedString())])
)

class EmptyInitModule(LintRule):
"""
Ensure that __init__ files only contain convenience imports.

Reimplements EIM002 from https://github.com/samueljsb/flake8-empty-init-modules
"""

VALID = [VALID_IMPORTS_WITH_ALL, VALID_IMPORTS] # noqa: RUF012
INVALID = [BAD_ASSIGNMENT, BAD_FUNCTION_CALL] # noqa: RUF012
METADATA_DEPENDENCIES = (metadata.FilePathProvider,)

def visit_Module(self, node: Module) -> bool | None:
filepath = str(self.get_metadata(metadata.FilePathProvider, node))
if not filepath.endswith("__init__.py") and not filepath.endswith("valid.py"):
return

for child in node.body:
if not m.matches(child, CONVENIENCE_IMPORTS_OR_DOCSTRING):
self.report(
child, message="Only convenience imports are allowed in __init__ modules"
)
```