fix(dependency_getter): handle strings for setuptools dynamic depen…

…dencies

python/deptry/dependency_getter/pep621/base.py

@@ -64,9 +64,11 @@ def _get_dependencies(self) -> list[Dependency]:
         if self._project_uses_setuptools(pyproject_data) and "dependencies" in pyproject_data["project"].get(
             "dynamic", {}
         ):
-            return get_dependencies_from_requirements_files(
-                pyproject_data["tool"]["setuptools"]["dynamic"]["dependencies"]["file"], self.package_module_name_map
-            )
+            dependencies_files = pyproject_data["tool"]["setuptools"]["dynamic"]["dependencies"]["file"]
+            if isinstance(dependencies_files, str):
+                dependencies_files = [dependencies_files]
+
+            return get_dependencies_from_requirements_files(dependencies_files, self.package_module_name_map)
 
         dependency_strings: list[str] = pyproject_data["project"].get("dependencies", [])
         return self._extract_pep_508_dependencies(dependency_strings)
@@ -79,7 +81,10 @@ def _get_optional_dependencies(self) -> dict[str, list[Dependency]]:
             "dynamic", {}
         ):
             return {
-                group: get_dependencies_from_requirements_files(specification["file"], self.package_module_name_map)
+                group: get_dependencies_from_requirements_files(
+                    [specification["file"]] if isinstance(specification["file"], str) else specification["file"],
+                    self.package_module_name_map,
+                )
                 for group, specification in pyproject_data["tool"]["setuptools"]["dynamic"]
                 .get("optional-dependencies", {})
                 .items()

tests/fixtures/project_with_setuptools_dynamic_dependencies/pyproject.toml

@@ -12,7 +12,8 @@ dynamic = ["dependencies", "optional-dependencies"]
 dependencies = { file = ["requirements.txt", "requirements-2.txt"] }
 
 [tool.setuptools.dynamic.optional-dependencies]
-cli = { file = ["cli-requirements.txt"] }
+# Both strings and list of strings are accepted.
+cli = { file = "cli-requirements.txt" }
 dev = { file = ["dev-requirements.txt"] }
 
 [tool.deptry]

tests/unit/dependency_getter/test_pep_621.py

@@ -286,7 +286,8 @@ def test_dependency_getter_with_setuptools_dynamic_dependencies_with_another_bui
 dependencies = { file = ["requirements.txt", "requirements-2.txt"] }
 
 [tool.setuptools.dynamic.optional-dependencies]
-cli = { file = ["cli-requirements.txt"] }
+# Both strings and list of strings are accepted.
+cli = { file = "cli-requirements.txt" }
 dev = { file = ["dev-requirements.txt"] }
 """