fix: display quiet Meson configuration errors

spin/cmds/meson.py

@@ -385,6 +385,8 @@ def build(
     if not (os.path.exists(build_dir) and _meson_version_configured(build_dir)):
         p = _run(setup_cmd, sys_exit=False, output=not quiet)
         if p.returncode != 0:
+            if quiet:
+                print(p.stdout.decode("utf-8"), end="")
             raise RuntimeError(
                 "Meson configuration failed; please try `spin build` again with the `--clean` flag."
             )

spin/tests/test_meson.py

@@ -4,11 +4,72 @@
 from os.path import join as pjoin
 from os.path import normpath
 
+import click
 import pytest
 
 from spin.cmds import meson
 from spin.containers import DotDict
 
+# Fake meson: prints to stdout and stderr, and fails for subcommands in FAILING_CMDS
+FAKE_MESON = """
+import sys
+
+FAILING_CMDS = {failing_cmds!r}
+
+subcommand = sys.argv[1]
+print("fake meson " + subcommand + ": stdout")
+print("fake meson " + subcommand + ": stderr", file=sys.stderr)
+sys.exit(1 if subcommand in FAILING_CMDS else 0)
+"""
+
+
+@pytest.fixture
+def fake_meson(tmp_path, monkeypatch):
+    """Return a factory that installs a fake meson and returns a build dir."""
+
+    def make(failing_cmds=()):
+        script = tmp_path / "meson.py"
+        script.write_text(FAKE_MESON.format(failing_cmds=list(failing_cmds)))
+        # Run the fake script in place of the meson binary
+        monkeypatch.setattr(meson, "_meson_cli", lambda: [sys.executable, str(script)])
+        monkeypatch.setattr(meson, "get_config", lambda: DotDict({}))
+        return str(tmp_path / "build")
+
+    return make
+
+
+def test_quiet_configuration_failure_output(fake_meson, capfd):
+    build_dir = fake_meson(failing_cmds=["setup"])
+    with pytest.raises(RuntimeError, match="Meson configuration failed"):
+        meson.build.callback(
+            meson_args=(), build_dir=build_dir, prefix="/usr", quiet=True
+        )
+    captured = capfd.readouterr()
+    output = captured.out + captured.err
+    assert output.count("fake meson setup: stdout") == 1
+    assert output.count("fake meson setup: stderr") == 1
+
+
+def test_run_configuration_failure_output(fake_meson, monkeypatch, capfd):
+    build_dir = fake_meson(failing_cmds=["setup"])
+    monkeypatch.setattr(meson, "_get_configured_command", lambda name: meson.build)
+    with (
+        click.Context(meson.run),
+        pytest.raises(RuntimeError, match="Meson configuration failed"),
+    ):
+        meson.run.callback(args=("unused-command",), build=True, build_dir=build_dir)
+    captured = capfd.readouterr()
+    assert "fake meson setup: stdout" in captured.err
+    assert "fake meson setup: stderr" in captured.err
+    assert "fake meson setup" not in captured.out
+
+
+def test_successful_quiet_build_output(fake_meson, capfd):
+    build_dir = fake_meson()
+    meson.build.callback(meson_args=(), build_dir=build_dir, prefix="/usr", quiet=True)
+    captured = capfd.readouterr()
+    assert "fake meson" not in captured.out + captured.err
+
 
 def make_paths(root, paths):
     for p in paths: