Prevent channel/dependency reordering when rendering the environment

CHANGELOG.rst

@@ -2,6 +2,14 @@
 CHANGELOG
 =========
 
+UNRELEASED
+----------
+
+- Dependency order is no longer sorted automatically, instead the order is preserved as they are defined in the ``*.devenv.yml`` files.
+  Usually this would not matter, but it is important for ``pip`` dependencies which declare development installations, as it is important
+  that those happen in the specified order.
+
+
 3.2.1 (2024-01-03)
 ------------------
 

src/conda_devenv/devenv.py

@@ -403,15 +403,15 @@ def merge_dependencies_version_specifications(
         else:
             raise UsageError(f"Only strings and dicts are supported, got: {dep!r}")
 
-    result = set()
+    # keep the order of dependencies
+    result: dict[str, Any] = collections.OrderedDict()
     for dep_name, dep_version_matchers in new_dependencies.items():
         if len(dep_version_matchers) > 0:
-            result.add(dep_name + " " + ",".join(dep_version_matchers))
+            result[dep_name + " " + ",".join(dep_version_matchers)] = None
         else:
-            result.add(dep_name)
+            result[dep_name] = None
 
-    new_dict_dependencies = sorted(new_dict_dependencies, key=lambda x: list(x.keys()))
-    yaml_dict[key_to_merge] = sorted(result) + new_dict_dependencies
+    yaml_dict[key_to_merge] = list(result.keys()) + new_dict_dependencies
 
 
 @dataclass(frozen=True)

tests/test_load_yaml_dict.py

@@ -191,6 +191,17 @@ def test_downstream_overrides_platforms(tmp_path) -> None:
     }
 
 
+def test_load_yaml_dict_dependency_order(datadir) -> None:
+    """
+    Make sure the order of channels and pip dependencies is preserved
+    """
+    conda_yaml_dict = load_yaml_dict(datadir / "deps_order.yml")
+    channels = conda_yaml_dict["channels"]
+    assert channels == ["pytorch", "nvidia", "conda-forge", "bioconda"]
+    pip_dependencies = conda_yaml_dict["dependencies"][3]
+    assert pip_dependencies["pip"] == ["-e c-package", "-e b-package", "-e D-package"]
+
+
 class TestConstraints:
     def test_no_constraints(self) -> None:
         data = {"dependencies": ["attrs >19", "boltons"]}

tests/test_load_yaml_dict/deps_order.yml

@@ -0,0 +1,16 @@
+name: test-env
+
+channels:
+  - pytorch
+  - nvidia
+  - conda-forge
+  - bioconda
+
+dependencies:
+  - pytorch
+  - numpy
+  - scikit-image
+  - pip:
+    - "-e c-package"
+    - "-e b-package"
+    - "-e D-package"