feat: Add local package support to pixi.toml generation

When generating pixi.toml files, UniDep now automatically detects
local pip-installable packages (those with setup.py or pyproject.toml
with [build-system]) and adds them as editable dependencies.

This allows Pixi to install the local packages in development mode,
similar to 'pip install -e .'.

Changes:
- Use is_pip_installable() to detect local packages
- Add local packages as editable dependencies in pypi-dependencies
- For single packages: use path='.'
- For monorepos: use path='./feature_name' for each feature
- Add test to verify local package detection and inclusion

Author: basnijholt

tests/test_pixi.py

@@ -161,6 +161,57 @@ def test_pixi_with_version_pins(tmp_path: Path) -> None:
     assert 'sympy = ">=1.11"' in content  # Space should be removed
 
 
+def test_pixi_with_local_package(tmp_path: Path) -> None:
+    """Test that local packages are added as editable dependencies."""
+    # Create a directory with requirements.yaml and pyproject.toml
+    project_dir = tmp_path / "my_package"
+    project_dir.mkdir()
+
+    req_file = project_dir / "requirements.yaml"
+    req_file.write_text(
+        textwrap.dedent(
+            """\
+            channels:
+              - conda-forge
+            dependencies:
+              - numpy
+            """,
+        ),
+    )
+
+    # Create a pyproject.toml with build-system to simulate a local package
+    pyproject_file = project_dir / "pyproject.toml"
+    pyproject_file.write_text(
+        textwrap.dedent(
+            """\
+            [build-system]
+            requires = ["setuptools"]
+
+            [project]
+            name = "my-package"
+            """,
+        ),
+    )
+
+    output_file = tmp_path / "pixi.toml"
+    generate_pixi_toml(
+        project_dir,
+        output_file=output_file,
+        verbose=False,
+    )
+
+    assert output_file.exists()
+    content = output_file.read_text()
+
+    # Check that the local package is added as an editable dependency
+    # TOML can format this as either inline or table format
+    assert "pypi-dependencies" in content
+    assert "my_package" in content
+    assert 'path = "."' in content
+    assert "editable = true" in content
+    assert 'numpy = "*"' in content
+
+
 def test_pixi_empty_dependencies(tmp_path: Path) -> None:
     """Test handling of requirements file with no dependencies."""
     req_file = tmp_path / "requirements.yaml"

unidep/_pixi.py

@@ -7,7 +7,7 @@
 from typing import TYPE_CHECKING, Any
 
 from unidep._dependencies_parsing import parse_requirements
-from unidep.utils import identify_current_platform
+from unidep.utils import identify_current_platform, is_pip_installable
 
 if TYPE_CHECKING:
     from unidep._dependencies_parsing import ParsedRequirements
@@ -23,7 +23,7 @@
     HAS_TOML = False
 
 
-def generate_pixi_toml(  # noqa: PLR0912
+def generate_pixi_toml(  # noqa: PLR0912, C901, PLR0915
     *requirements_files: Path,
     project_name: str | None = None,
     channels: list[str] | None = None,
@@ -61,6 +61,20 @@ def generate_pixi_toml(  # noqa: PLR0912
             pixi_data["dependencies"] = conda_deps
         if pip_deps:
             pixi_data["pypi-dependencies"] = pip_deps
+
+        # Check if there's a local package in the same directory
+        req_file = requirements_files[0]
+        req_dir = req_file.parent if req_file.is_file() else req_file
+        if is_pip_installable(req_dir):
+            # Add the local package as an editable dependency
+            if "pypi-dependencies" not in pixi_data:
+                pixi_data["pypi-dependencies"] = {}
+            # For single package, use current directory
+            package_name = req_dir.name
+            pixi_data["pypi-dependencies"][package_name] = {
+                "path": ".",
+                "editable": True,
+            }
     else:
         # Multiple files: create features
         pixi_data["feature"] = {}
@@ -84,6 +98,19 @@ def generate_pixi_toml(  # noqa: PLR0912
             if pip_deps:
                 feature["pypi-dependencies"] = pip_deps
 
+            # Check if there's a local package in the same directory
+            req_dir = req_file.parent if req_file.is_file() else req_file
+            if is_pip_installable(req_dir):
+                # Add the local package as an editable dependency
+                if "pypi-dependencies" not in feature:
+                    feature["pypi-dependencies"] = {}
+                # Use relative path from the output file location
+                rel_path = f"./{feature_name}"
+                feature["pypi-dependencies"][feature_name] = {
+                    "path": rel_path,
+                    "editable": True,
+                }
+
             if feature:  # Only add non-empty features
                 pixi_data["feature"][feature_name] = feature
                 all_features.append(feature_name)