fix: differ between not defined and empty dependency list (#892)

Author: finswimmer

src/poetry/core/factory.py

@@ -377,12 +377,14 @@ def _configure_package_dependencies(
         from poetry.core.packages.dependency_group import MAIN_GROUP
         from poetry.core.packages.dependency_group import DependencyGroup
 
-        dependencies = project.get("dependencies", {})
+        dependencies = project.get("dependencies")
         optional_dependencies = project.get("optional-dependencies", {})
         dynamic = project.get("dynamic", [])
 
         package_extras: dict[NormalizedName, list[Dependency]]
-        if dependencies or optional_dependencies:
+        if dependencies is not None or optional_dependencies:
+            dependencies = dependencies or {}
+
             group = DependencyGroup(
                 MAIN_GROUP,
                 mixed_dynamic=(

tests/fixtures/sample_project_new_no_deps/pyproject.toml

@@ -0,0 +1,22 @@
+[project]
+name = "my-package"
+version = "1.2.3"
+description = "Some description."
+requires-python = ">=3.6"
+license = "MIT"
+keywords = ["packaging", "dependency", "poetry"]
+authors = [
+    { name = "Sébastien Eustace", email = "[email protected]" }
+]
+maintainers = [
+    { name = "Sébastien Eustace", email = "[email protected]" }
+]
+
+classifiers = [
+    "Topic :: Software Development :: Build Tools",
+    "Topic :: Software Development :: Libraries :: Python Modules"
+]
+
+# Requirements
+dependencies = [
+]

tests/test_factory.py

@@ -313,6 +313,18 @@ def test_create_poetry(project: str) -> None:
         ]
 
 
+def test_create_poetry_with_empty_dependencies() -> None:
+    project = "sample_project_new_no_deps"
+    poetry = Factory().create_poetry(fixtures_dir / project)
+
+    assert poetry.is_package_mode
+
+    package = poetry.package
+
+    assert "main" in package._dependency_groups
+    assert package._dependency_groups[canonicalize_name("main")].dependencies == []
+
+
 @pytest.mark.parametrize(
     "project", ["sample_project_with_groups", "sample_project_with_groups_new"]
 )