Handle circular dependency on root package (fix #118)

src/poetry_plugin_export/exporter.py

@@ -95,6 +95,7 @@ def _export_generic_txt(
         for dependency_package in get_project_dependency_packages(
             self._poetry.locker,
             project_requires=root.all_requires,
+            root_package_name=root.name,
             project_python_marker=root.python_marker,
             extras=self._extras,
         ):

src/poetry_plugin_export/walker.py

@@ -52,6 +52,7 @@ def get_python_version_region_markers(packages: list[Package]) -> list[BaseMarke
 def get_project_dependency_packages(
     locker: Locker,
     project_requires: list[Dependency],
+    root_package_name: NormalizedName,
     project_python_marker: BaseMarker | None = None,
     extras: Collection[NormalizedName] = (),
 ) -> Iterator[DependencyPackage]:
@@ -96,13 +97,15 @@ def get_project_dependency_packages(
     for package, dependency in get_project_dependencies(
         project_requires=selected,
         locked_packages=repository.packages,
+        root_package_name=root_package_name,
     ):
         yield DependencyPackage(dependency=dependency, package=package)
 
 
 def get_project_dependencies(
     project_requires: list[Dependency],
     locked_packages: list[Package],
+    root_package_name: NormalizedName,
 ) -> Iterable[tuple[Package, Dependency]]:
     # group packages entries by name, this is required because requirement might use
     # different constraints.
@@ -122,6 +125,7 @@ def get_project_dependencies(
     nested_dependencies = walk_dependencies(
         dependencies=project_requires,
         packages_by_name=packages_by_name,
+        root_package_name=root_package_name,
     )
 
     return nested_dependencies.items()
@@ -130,6 +134,7 @@ def get_project_dependencies(
 def walk_dependencies(
     dependencies: list[Dependency],
     packages_by_name: dict[str, list[Package]],
+    root_package_name: NormalizedName,
 ) -> dict[Package, Dependency]:
     nested_dependencies: dict[Package, Dependency] = {}
 
@@ -138,6 +143,8 @@ def walk_dependencies(
         requirement = dependencies.pop(0)
         if (requirement, requirement.marker) in visited:
             continue
+        if requirement.name == root_package_name:
+            continue
         visited.add((requirement, requirement.marker))
 
         locked_package = get_locked_package(

tests/test_exporter.py

@@ -1115,6 +1115,43 @@ def test_exporter_can_export_requirements_txt_with_nested_packages_cyclic(
     assert content == expected
 
 
+def test_exporter_can_export_requirements_txt_with_circular_root_dependency(
+    tmp_path: Path, poetry: Poetry
+) -> None:
+    poetry.locker.mock_lock_data(  # type: ignore[attr-defined]
+        {
+            "package": [
+                {
+                    "name": "foo",
+                    "version": "1.2.3",
+                    "category": "main",
+                    "optional": False,
+                    "python-versions": "*",
+                    "dependencies": {poetry.package.pretty_name: {"version": "1.2.3"}},
+                },
+            ],
+            "metadata": {
+                "python-versions": "*",
+                "content-hash": "123456789",
+                "files": {"foo": []},
+            },
+        }
+    )
+    set_package_requires(poetry)
+
+    exporter = Exporter(poetry, NullIO())
+    exporter.export("requirements.txt", tmp_path, "requirements.txt")
+
+    with (tmp_path / "requirements.txt").open(encoding="utf-8") as f:
+        content = f.read()
+
+    expected = f"""\
+foo==1.2.3 ; {MARKER_PY}
+"""
+
+    assert content == expected
+
+
 def test_exporter_can_export_requirements_txt_with_nested_packages_and_multiple_markers(
     tmp_path: Path, poetry: Poetry
 ) -> None: