Fix Path.exists() method calls in assertion functions

The exists, is_file, and is_dir attributes were being referenced
without calling them as methods, causing assertions to always pass.

Author: Nils Bars

ref_utils/assertion.py

@@ -1,14 +1,11 @@
 """Exception-free assert functions"""
-from pathlib import Path
-from typing import Any, Union # pylint: disable = unused-import
-
-from .error import RefUtilsAssertionError
-
-import signal
 import os
+from pathlib import Path
+from typing import Any, Union  # pylint: disable = unused-import
 
 from .utils import print_err
 
+
 def _assert(condition: bool, error_msg: str, silent: bool) -> bool:
     """Custom 'assertion' that prints a warning rather than throwing AssertionError"""
     if not condition:
@@ -21,17 +18,17 @@ def assert_is_exec(executable: Union[str, 'os.PathLike[Any]', Path], silent: boo
     """Assert file exists and is executable"""
     if not isinstance(executable, Path):
         return assert_is_exec(Path(executable))
-    return _assert(executable.exists and executable.is_file() and os.access(executable, os.X_OK),
+    return _assert(executable.exists() and executable.is_file() and os.access(executable, os.X_OK),
                    f"Executable file {executable} not found or not executable", silent)
 
 def assert_is_file(file_: Union[str, 'os.PathLike[Any]', Path], silent: bool = False) -> bool:
     """Assert file exists"""
     if not isinstance(file_, Path):
         return assert_is_file(Path(file_))
-    return _assert(file_.exists and file_.is_file(), f"File {file_} not found", silent)
+    return _assert(file_.exists() and file_.is_file(), f"File {file_} not found", silent)
 
 def assert_is_dir(directory: Union[str, 'os.PathLike[Any]', Path], silent: bool = False) -> bool:
     """Assert directory exists"""
     if not isinstance(directory, Path):
         return assert_is_dir(Path(directory))
-    return _assert(directory.exists and directory.is_dir(), f"Directory {directory} not found", silent)
+    return _assert(directory.exists() and directory.is_dir(), f"Directory {directory} not found", silent)