add test for cargo log output

Author: davidhewitt

.github/workflows/ci.yml

@@ -48,6 +48,13 @@ jobs:
         with:
           python-version: "3.x"
 
+      - name: Install Rust toolchain
+        uses: actions-rs/toolchain@v1
+        with:
+          toolchain: stable
+          profile: minimal
+          default: true
+
       - run: pip install nox
 
       - run: nox -s test

tests/test_extension.py

@@ -0,0 +1,40 @@
+from pathlib import Path
+
+import pytest
+from pytest import CaptureFixture, MonkeyPatch
+
+from setuptools_rust.extension import RustBin
+
+
+@pytest.fixture()
+def hello_world_bin() -> RustBin:
+    setuptools_rust_dir = Path(__file__).parent.parent
+    return RustBin(
+        "hello-world",
+        path=(
+            setuptools_rust_dir / "examples" / "hello-world" / "Cargo.toml"
+        ).as_posix(),
+    )
+
+
+def test_metadata_contents(hello_world_bin: RustBin) -> None:
+    metadata = hello_world_bin._metadata(quiet=False)
+    assert "target_directory" in metadata
+
+
+def test_metadata_cargo_log(
+    capfd: CaptureFixture, monkeypatch: MonkeyPatch, hello_world_bin: RustBin
+) -> None:
+    monkeypatch.setenv("CARGO_LOG", "trace")
+
+    # With quiet unset, no stdout, plenty of logging stderr
+    hello_world_bin._metadata(quiet=False)
+    captured = capfd.readouterr()
+    assert captured.out == ""
+    assert "TRACE cargo::util::config" in captured.err
+
+    # With quiet set, nothing will be printed
+    hello_world_bin._metadata(quiet=True)
+    captured = capfd.readouterr()
+    assert captured.out == ""
+    assert captured.err == ""