fix(dependency_getter): avoid error on empty dependencies (#752)

* fix(dependency_getter): avoid error on empty dependencies

* fix(dependency_getter): only check for `tool.poetry` to detect Poetry

Author: mkniewallner

python/deptry/dependency_getter/builder.py

@@ -71,14 +71,14 @@ def _project_contains_pyproject_toml(self) -> bool:
     @staticmethod
     def _project_uses_poetry(pyproject_toml: dict[str, Any]) -> bool:
         try:
-            pyproject_toml["tool"]["poetry"]["dependencies"]
+            pyproject_toml["tool"]["poetry"]
             logging.debug(
-                "pyproject.toml contains a [tool.poetry.dependencies] section, so Poetry is used to specify the"
+                "pyproject.toml contains a [tool.poetry] section, so Poetry is used to specify the"
                 " project's dependencies."
             )
         except KeyError:
             logging.debug(
-                "pyproject.toml does not contain a [tool.poetry.dependencies] section, so Poetry is not used to specify"
+                "pyproject.toml does not contain a [tool.poetry] section, so Poetry is not used to specify"
                 " the project's dependencies."
             )
             return False

python/deptry/dependency_getter/pep_621.py

@@ -58,7 +58,7 @@ def get(self) -> DependenciesExtract:
 
     def _get_dependencies(self) -> list[Dependency]:
         pyproject_data = load_pyproject_toml(self.config)
-        dependency_strings: list[str] = pyproject_data["project"]["dependencies"]
+        dependency_strings: list[str] = pyproject_data["project"].get("dependencies", [])
         return self._extract_pep_508_dependencies(dependency_strings, self.package_module_name_map)
 
     def _get_optional_dependencies(self) -> dict[str, list[Dependency]]:

python/deptry/dependency_getter/poetry.py

@@ -21,7 +21,7 @@ def get(self) -> DependenciesExtract:
 
     def _get_poetry_dependencies(self) -> list[Dependency]:
         pyproject_data = load_pyproject_toml(self.config)
-        dependencies: dict[str, Any] = pyproject_data["tool"]["poetry"]["dependencies"]
+        dependencies: dict[str, Any] = pyproject_data["tool"]["poetry"].get("dependencies", {})
         return self._get_dependencies(dependencies, self.package_module_name_map)
 
     def _get_poetry_dev_dependencies(self) -> list[Dependency]:

tests/unit/dependency_getter/test_builder.py

@@ -123,7 +123,7 @@ def test_dependency_specification_not_found_raises_exception(tmp_path: Path, cap
     assert caplog.messages == [
         "pyproject.toml found!",
         (
-            "pyproject.toml does not contain a [tool.poetry.dependencies] section, so Poetry is not used to specify the"
+            "pyproject.toml does not contain a [tool.poetry] section, so Poetry is not used to specify the"
             " project's dependencies."
         ),
         (

tests/unit/dependency_getter/test_pep_621.py

@@ -147,3 +147,20 @@ def test_dependency_getter_with_incorrect_dev_group(tmp_path: Path, caplog: LogC
 
         assert dependencies[2].name == "barfoo"
         assert "barfoo" in dependencies[2].top_levels
+
+
+def test_dependency_getter_empty_dependencies(tmp_path: Path) -> None:
+    fake_pyproject_toml = """[project]
+# PEP 621 project metadata
+# See https://www.python.org/dev/peps/pep-0621/
+"""
+
+    with run_within_dir(tmp_path):
+        with Path("pyproject.toml").open("w") as f:
+            f.write(fake_pyproject_toml)
+
+        getter = PEP621DependencyGetter(config=Path("pyproject.toml"))
+        dependencies_extract = getter.get()
+
+        assert len(dependencies_extract.dependencies) == 0
+        assert len(dependencies_extract.dev_dependencies) == 0

tests/unit/dependency_getter/test_poetry.py

@@ -8,6 +8,9 @@
 
 def test_dependency_getter(tmp_path: Path) -> None:
     fake_pyproject_toml = """
+[tool.poetry]
+name = "foo"
+
 [tool.poetry.dependencies]
 python = ">=3.7,<4.0"
 bar =  { version = ">=2.5.1,<4.0.0", python = ">3.7" }
@@ -68,3 +71,20 @@ def test_dependency_getter(tmp_path: Path) -> None:
 
         assert dev_dependencies[5].name == "pytest-cov"
         assert "pytest_cov" in dev_dependencies[5].top_levels
+
+
+def test_dependency_getter_empty_dependencies(tmp_path: Path) -> None:
+    fake_pyproject_toml = """
+[tool.poetry]
+name = "foo"
+"""
+
+    with run_within_dir(tmp_path):
+        with Path("pyproject.toml").open("w") as f:
+            f.write(fake_pyproject_toml)
+
+        getter = PoetryDependencyGetter(config=Path("pyproject.toml"))
+        dependencies_extract = getter.get()
+
+        assert len(dependencies_extract.dependencies) == 0
+        assert len(dependencies_extract.dev_dependencies) == 0