fix(rust_plugin): fix dependency validation logic

craft_parts/plugins/rust_plugin.py

@@ -85,9 +85,14 @@ def validate_environment(
 
         :param part_dependencies: A list of the parts this part depends on.
         """
-        if "rust-deps" in (part_dependencies or []):
-            options = cast(RustPluginProperties, self._options)
-            if options.rust_channel and options.rust_channel != "none":
+        options = cast(RustPluginProperties, self._options)
+        has_rust_deps = "rust-deps" in (part_dependencies or [])
+        if has_rust_deps or options.rust_channel == "none":
+            if (
+                has_rust_deps
+                and options.rust_channel
+                and options.rust_channel != "none"
+            ):
                 raise validator.errors.PluginEnvironmentValidationError(
                     part_name=self._part_name,
                     reason="rust-deps can not be used"
@@ -99,6 +104,14 @@ def validate_environment(
                     plugin_name="rust",
                     part_dependencies=part_dependencies,
                 )
+            return
+        # Check if rustup is properly installed
+        self.validate_dependency(
+            dependency="rustup",
+            argument="dump-testament",
+            plugin_name="rust",
+            part_dependencies=part_dependencies,
+        )
 
 
 class RustPlugin(Plugin):
@@ -172,6 +185,8 @@ def get_build_snaps(self) -> set[str]:
         if not options.rust_channel and self._check_system_rust():
             logger.info("Rust is installed on the system, skipping rustup")
             return set()
+        if options.rust_channel == "none" or "rust-deps" in (options.after or []):
+            return set()
         return {"rustup"}
 
     @override

tests/unit/plugins/test_rust_plugin.py

@@ -21,6 +21,7 @@
 from craft_parts.infos import PartInfo, ProjectInfo
 from craft_parts.parts import Part
 from craft_parts.plugins.rust_plugin import RustPlugin, RustPluginProperties
+from craft_parts.plugins.validator import PluginEnvironmentValidator
 from pydantic import ValidationError
 
 
@@ -32,6 +33,17 @@ def part_info(new_dir):
     )
 
 
+@pytest.fixture
+def mock_validator(monkeypatch):
+    def fake_execute(self, cmd: str):
+        return subprocess.check_output(  # noqa: S602
+            cmd,
+            shell=True,
+        )
+
+    monkeypatch.setattr(PluginEnvironmentValidator, "_execute", fake_execute)
+
+
 @pytest.mark.parametrize(
     "rust_channel",
     [
@@ -262,6 +274,56 @@ def callback_fail():
     ]
 
 
+@pytest.mark.parametrize("after", [["something-else"], []])
+def test_validate_environment_should_have_rustup(
+    after, fake_process: pytest_subprocess.FakeProcess, mock_validator
+):
+    def exec_fail(x):
+        raise subprocess.CalledProcessError(127, x)
+
+    fake_process.register(
+        ["cargo", "--version"], stdout="cargo 1.84.0-nightly (69e595908 2024-11-16)"
+    )
+    fake_process.register(
+        ["rustc", "--version"], stdout="rustc 1.84.0-nightly (5ec7d6eee 2024-11-17)"
+    )
+    fake_process.register(["rustup", "dump-testament"], callback=exec_fail)
+
+    properties = RustPlugin.properties_class.unmarshal({"source": ".", "after": after})
+    validator = RustPlugin.validator_class(
+        part_name="my-part", properties=properties, env=""
+    )
+    # positive test
+    validator.validate_environment(part_dependencies=["rust-deps"])
+    # negative test
+    with pytest.raises(PluginEnvironmentValidationError):
+        validator.validate_environment(part_dependencies=after)
+
+
+def test_validate_environment_should_not_have_rustup(
+    fake_process: pytest_subprocess.FakeProcess, mock_validator
+):
+    def exec_fail(x):
+        raise subprocess.CalledProcessError(127, x)
+
+    fake_process.register(["cargo", "--version"], callback=exec_fail)
+    fake_process.register(["rustc", "--version"], callback=exec_fail)
+    fake_process.register(
+        ["rustup", "dump-testament"],
+        stdout="Rustup version renders as: 1.27.1 (2024-05-07)",
+    )
+
+    properties = RustPlugin.properties_class.unmarshal(
+        {"source": ".", "after": ["rust-deps"]}
+    )
+    validator = RustPlugin.validator_class(
+        part_name="my-part", properties=properties, env=""
+    )
+    # positive test
+    validator.validate_environment(part_dependencies=[])
+    validator.validate_environment(part_dependencies=["rust-deps"])
+
+
 def test_get_out_of_source_build(part_info):
     properties = RustPlugin.properties_class.unmarshal({"source": "."})
     plugin = RustPlugin(properties=properties, part_info=part_info)