Add class for existing files

docs/CHANGELOG.md

@@ -15,3 +15,4 @@
 - Add feature to compare `core.python.namespaces.PythonPackageNamespace` instances or `core.python.namespaces.PythonModuleNamespace` instances
 - Add string representation for python namespace objects
 - Add `PythonDocumentationGenerator` method to collect all namespaces
+- Add class for existing files

src/jcloud_docsgen/utils.py

@@ -24,7 +24,7 @@ import types
 
 class ExistingDirectory(pathlib.Path):
     '''
-    pathlib.Path subclass that is a directory
+    pathlib.Path subclass that is a directory.
 
     ExistingDirectory represents a filesystem path but it also checks
     whether the path exists and is not a file but a directory. It
@@ -37,6 +37,21 @@ class ExistingDirectory(pathlib.Path):
             raise NotADirectoryError(errno.ENOTDIR, 'not a directory', path)
         super().__init__(*(path, *args), **kwargs)
 
+class ExistingFile(pathlib.Path):
+    '''
+    pathlib.Path subclass that is a file.
+
+    ExistingFile represents a filesystem path but it also checks whether
+    the path exists and is not a directory but a file. It inherits from
+    pathlib.Path.
+    '''
+    def __init__(self, path, *args, **kwargs) -> None:
+        if not os.path.exists(path):
+            raise FileNotFoundError(errno.ENOENT, 'no such file or directory', path)
+        if not os.path.isfile(path):
+            raise IsADirectoryError(errno.EISDIR, 'is a directory', path)
+        super().__init__(*(path, *args), **kwargs)
+
 def _quote(string: str, quotation_mark: str) -> str:
     '''
     Quotes a string.

tests/unit/utils/test_ExistingFile.py

@@ -0,0 +1,22 @@
+from src.jcloud_docsgen.utils import ExistingFile
+import pytest
+import pathlib
+
+@pytest.mark.parametrize('path,expected', [
+    ('tests/unit/utils/test_file', 'tests/unit/utils/test_file'),
+    ('tests/unit/utils/test_symlink', 'tests/unit/utils/test_symlink'),
+])
+def test_ExistingDirectory(path, expected):
+    assert ExistingFile(path).as_posix() == expected
+
+@pytest.mark.parametrize('path,expected_exception,expected_exception_message', [
+    ('tests/unit/utils/does_not_exist', FileNotFoundError, '[Errno 2] no such file or directory: \'tests/unit/utils/does_not_exist\''),
+    ('', FileNotFoundError, '[Errno 2] no such file or directory: \'\''),
+    ('tests/unit/utils/test_directory', IsADirectoryError, '[Errno 21] is a directory: \'tests/unit/utils/test_directory\''),
+    ('.', IsADirectoryError, '[Errno 21] is a directory: \'.\''),
+    ('./', IsADirectoryError, '[Errno 21] is a directory: \'./\''),
+])
+def test_ExistingDirectory_exceptions(path, expected_exception, expected_exception_message):
+    with pytest.raises(expected_exception) as exc_info:
+        ExistingFile(path)
+    assert str(exc_info.value) == expected_exception_message