Platforms and channels are now defined by the most-downstream devenv …

…file

Previously the `name`, `channels`, and `platforms` keys would only be overwritten by the root `devenv.yml` file (the one use to invoke `conda devenv` with).

Now any downstream `devenv.yml` file will override these keys, with the most downstream `devenv.yml` file "winning", which was always the intended behavior.

CHANGELOG.rst

@@ -2,6 +2,12 @@
 CHANGELOG
 =========
 
+3.4.0 (UNRELEASED)
+------------------
+
+* Previously the ``name``, ``channels``, and ``platforms`` keys would only be overwritten by the root ``devenv.yml`` file (the one use to invoke ``conda devenv`` with).
+  Now any downstream ``devenv.yml`` file will override these keys, with the most downstream ``devenv.yml`` file "winning", which was always the intended behavior.
+
 3.3.0 (2024-02-21)
 ------------------
 

src/conda_devenv/devenv.py

@@ -499,10 +499,13 @@ def load_yaml_dict(
 
     merge_dependencies_version_specifications(merged_dict, key_to_merge="dependencies")
 
-    # Force these keys to always be set by the starting/root devenv file, when defined.
-    force_root_keys = ("name", "channels", "platforms")
-    forced_keys = {k: root_yaml[k] for k in force_root_keys if k in root_yaml}
-    merged_dict.update(forced_keys)
+    # Force these keys to always be set by the most downstream devenv file.
+    # all_yaml_dicts is ordered from downstream to upstream.
+    for forced_key in ("name", "channels", "platforms"):
+        for yaml_dict in all_yaml_dicts.values():
+            if forced_key in yaml_dict:
+                merged_dict[forced_key] = yaml_dict[forced_key]
+                break
 
     if "environment" not in merged_dict:
         merged_dict["environment"] = {}

tests/test_load_yaml_dict.py

@@ -136,6 +136,8 @@ def test_downstream_overrides_channels(tmp_path) -> None:
         )
     )
 
+    # This is the most downstream file which defines 'channels', so it overwrites any
+    # upstream definition.
     b_fn = tmp_path / "b.devenv.yml"
     b_fn.write_text(
         textwrap.dedent(
@@ -150,13 +152,114 @@ def test_downstream_overrides_channels(tmp_path) -> None:
         )
     )
 
-    assert load_yaml_dict(b_fn) == {
-        "name": "b",
+    c_fn = tmp_path / "c.devenv.yml"
+    c_fn.write_text(
+        textwrap.dedent(
+            """
+            name: c
+            includes:
+              - {{ root }}/b.devenv.yml
+            """
+        )
+    )
+
+    assert load_yaml_dict(c_fn) == {
+        "name": "c",
         "channels": ["b1_channel", "b2_channel"],
         "environment": {},
     }
 
 
+def test_no_downstream_overrides_channels(tmp_path) -> None:
+    # The 'channels' key is defined only by one upstream file.
+    a_fn = tmp_path / "a.devenv.yml"
+    a_fn.write_text(
+        textwrap.dedent(
+            """
+            name: a
+            channels:
+            - z_channel
+            - a_channel
+            """
+        )
+    )
+
+    b_fn = tmp_path / "b.devenv.yml"
+    b_fn.write_text(
+        textwrap.dedent(
+            """
+            name: b
+            includes:
+              - {{ root }}/a.devenv.yml
+            """
+        )
+    )
+
+    c_fn = tmp_path / "c.devenv.yml"
+    c_fn.write_text(
+        textwrap.dedent(
+            """
+            name: c
+            includes:
+              - {{ root }}/b.devenv.yml
+            """
+        )
+    )
+
+    assert load_yaml_dict(c_fn) == {
+        "name": "c",
+        "channels": ["z_channel", "a_channel"],
+        "environment": {},
+    }
+
+
+def test_root_overrides_channels(tmp_path) -> None:
+    a_fn = tmp_path / "a.devenv.yml"
+    a_fn.write_text(
+        textwrap.dedent(
+            """
+            name: a
+            channels:
+            - z_channel
+            - a_channel
+            """
+        )
+    )
+
+    b_fn = tmp_path / "b.devenv.yml"
+    b_fn.write_text(
+        textwrap.dedent(
+            """
+            name: b
+            includes:
+              - {{ root }}/a.devenv.yml
+            """
+        )
+    )
+
+    # This is the root file, so it overwrites the 'channels' completely.
+    c_fn = tmp_path / "c.devenv.yml"
+    c_fn.write_text(
+        textwrap.dedent(
+            """
+            name: c
+            includes:
+              - {{ root }}/b.devenv.yml
+            channels:
+            - a_channel
+            - z_channel
+            - b_channel
+            """
+        )
+    )
+
+    assert load_yaml_dict(c_fn) == {
+        "name": "c",
+        "channels": ["a_channel", "z_channel", "b_channel"],
+        "environment": {},
+    }
+
+
 def test_downstream_overrides_platforms(tmp_path) -> None:
     a_fn = tmp_path / "a.devenv.yml"
     a_fn.write_text(
@@ -170,22 +273,124 @@ def test_downstream_overrides_platforms(tmp_path) -> None:
         )
     )
 
+    # This is the most downstream file which defines 'platforms', so it overwrites any
+    # upstream definition.
+    b_fn = tmp_path / "b.devenv.yml"
+    b_fn.write_text(
+        textwrap.dedent(
+            """
+            name: b
+            includes:
+              - {{ root }}/a.devenv.yml
+            platforms:
+            - win-64
+            - osx-64
+            """
+        )
+    )
+
+    c_fn = tmp_path / "c.devenv.yml"
+    c_fn.write_text(
+        textwrap.dedent(
+            """
+            name: c
+            includes:
+              - {{ root }}/b.devenv.yml
+            """
+        )
+    )
+
+    assert load_yaml_dict(c_fn) == {
+        "name": "c",
+        "platforms": ["win-64", "osx-64"],
+        "environment": {},
+    }
+
+
+def test_no_downstream_overrides_platforms(tmp_path) -> None:
+    # The 'platforms' key is defined only by one upstream file.
+    a_fn = tmp_path / "a.devenv.yml"
+    a_fn.write_text(
+        textwrap.dedent(
+            """
+            name: a
+            platforms:
+            - win-64
+            - linux-64
+            """
+        )
+    )
+
+    b_fn = tmp_path / "b.devenv.yml"
+    b_fn.write_text(
+        textwrap.dedent(
+            """
+            name: b
+            includes:
+              - {{ root }}/a.devenv.yml
+            """
+        )
+    )
+
+    c_fn = tmp_path / "c.devenv.yml"
+    c_fn.write_text(
+        textwrap.dedent(
+            """
+            name: c
+            includes:
+              - {{ root }}/b.devenv.yml
+            """
+        )
+    )
+
+    assert load_yaml_dict(c_fn) == {
+        "name": "c",
+        "platforms": ["win-64", "linux-64"],
+        "environment": {},
+    }
+
+
+def test_root_overrides_platforms(tmp_path) -> None:
+    a_fn = tmp_path / "a.devenv.yml"
+    a_fn.write_text(
+        textwrap.dedent(
+            """
+            name: a
+            platforms:
+            - win-64
+            - linux-64
+            """
+        )
+    )
+
     b_fn = tmp_path / "b.devenv.yml"
     b_fn.write_text(
         textwrap.dedent(
             """
             name: b
             includes:
               - {{ root }}/a.devenv.yml
+            """
+        )
+    )
+
+    # This is the root file, so it overwrites the 'platforms' completely.
+    c_fn = tmp_path / "c.devenv.yml"
+    c_fn.write_text(
+        textwrap.dedent(
+            """
+            name: c
+            includes:
+              - {{ root }}/b.devenv.yml
             platforms:
             - win-64
             - osx-64
             """
         )
     )
 
-    assert load_yaml_dict(b_fn) == {
-        "name": "b",
+    assert load_yaml_dict(c_fn) == {
+        "name": "c",
         "platforms": ["win-64", "osx-64"],
         "environment": {},
     }