test(python-generator): add tests for force overwriting

Added tests to test new output directory deletion behavior:
  - output directory overwriting (not empty; force)
  - error (not empty; not force)
  - nothing (empty; force)
  - nothing (empty; not force)
One test was adapted to output directory emptiness check because the
.gitkeep file which is required for Git to track the directory makes it
non-empty.

tests/unit/core/python/_core/test_PythonDocumentationGenerator.py

@@ -18,6 +18,7 @@ import pytest
 
 import tempfile
 
+from src.jcloud_docsgen.exceptions import DirectoryNotEmptyError
 from src.jcloud_docsgen.core.python import PythonDocumentationGenerator
 from src.jcloud_docsgen.core.python.namespaces import (
     PythonModuleNamespace,
@@ -120,7 +121,7 @@ def test_generate_documentation(dir, expectdir):
             pathlib.Path(str(d)),
             allow_tables=True,
             allow_html=False,
-        ).generate_documentation()  # simplify the tests
+        ).generate_documentation(True)  # simplify the tests
 
 
 def test_creates_directory():
@@ -144,3 +145,51 @@ def test_creates_directory():
             )
             docs_generator.generate_documentation()
             assert docs_dir.exists()
+
+
+class TestForce:
+    def _prepare(self, directory):
+        directory = pathlib.Path(directory)
+        src_directory = directory / 'src'
+        src_directory.mkdir()
+        docs_directory = directory / 'docs'
+        docs_directory.mkdir()
+        return directory, src_directory, docs_directory
+
+    def test_overwrites_output_directory(self):
+        with tempfile.TemporaryDirectory() as directory:
+            directory, src_directory, docs_directory = self._prepare(directory)
+            test_dir = docs_directory / 'test_dir'
+            test_dir.mkdir()
+            documentation_generator = PythonDocumentationGenerator(
+                src_directory, docs_directory
+            )
+            documentation_generator.generate_documentation(True)
+            assert not test_dir.exists()
+
+    def test_error(self):
+        with tempfile.TemporaryDirectory() as directory:
+            directory, src_directory, docs_directory = self._prepare(directory)
+            (docs_directory / 'test_dir').mkdir()
+            documentation_generator = PythonDocumentationGenerator(
+                src_directory, docs_directory
+            )
+            with pytest.raises(DirectoryNotEmptyError) as exc_info:
+                documentation_generator.generate_documentation()
+            assert exc_info.value.filename == str(docs_directory)
+
+    def test_nothing_force(self):
+        with tempfile.TemporaryDirectory() as directory:
+            directory, src_directory, docs_directory = self._prepare(directory)
+            documentation_generator = PythonDocumentationGenerator(
+                src_directory, docs_directory
+            )
+            documentation_generator.generate_documentation(True)
+
+    def test_nothing_not_force(self):
+        with tempfile.TemporaryDirectory() as directory:
+            directory, src_directory, docs_directory = self._prepare(directory)
+            documentation_generator = PythonDocumentationGenerator(
+                src_directory, docs_directory
+            )
+            documentation_generator.generate_documentation(True)