updated tests for readme generations

tests/renderers/mkdocs/test_mkdocs_idempotency.py

@@ -18,3 +18,36 @@ def test_mkdocs_idempotent(tmp_path: Path):
     second = (out_dir / "testpkg" / "mod.md").read_text()
 
     assert first == second
+
+
+def test_generate_readme_idempotent(tmp_path: Path):
+    project = Project("testpkg")
+
+    root = Module("testpkg")
+    root.docstring = "Test package documentation."
+
+    project.add_module(root)
+
+    docs_dir = tmp_path / "docs"
+
+    renderer = MkDocsRenderer()
+
+    renderer.generate_readme(
+        project,
+        docs_dir,
+        module_is_source=True,
+    )
+
+    readme = tmp_path / "README.md"
+
+    first = readme.read_text()
+
+    renderer.generate_readme(
+        project,
+        docs_dir,
+        module_is_source=True,
+    )
+
+    second = readme.read_text()
+
+    assert first == second