Do not print unsupported mixin command errors

cmd/testmixin/main.go

@@ -25,7 +25,9 @@ func main() {
 		// This is a mixin that helps us test out our schema command
 		fmt.Println(schema)
 	case "lint":
-		fmt.Println("[]")
+		// The test mixin does not implement lint
+		fmt.Fprintln(os.Stderr, `unknown command "lint" for "testmixin"`)
+		os.Exit(1)
 	case "build":
 		fmt.Println("# testmixin")
 	case "run":

pkg/pkgmgmt/client/runner.go

@@ -99,7 +99,11 @@ func (r *Runner) Run(ctx context.Context, commandOpts pkgmgmt.CommandOptions) er
 	err = cmd.Wait()
 	if err != nil {
 		// Include stderr in the error, otherwise it just includes the exit code
-		return span.Error(fmt.Errorf("package command failed %s\n%s", prettyCmd, cmdStderr))
+		err = fmt.Errorf("package command failed %s\n%s", prettyCmd, cmdStderr)
+		// Do not flag this as an error in the logs because we often call mixins to see if they support a command
+		// and if they don't it's not an error, e.g. not all mixins support lint or schema
+		span.Debugf(err.Error())
+		return err
 	}
 
 	return nil

tests/integration/lint_test.go

@@ -0,0 +1,38 @@
+//go:build integration
+
+package integration
+
+import (
+	"path/filepath"
+	"testing"
+
+	"get.porter.sh/porter/tests/tester"
+	"github.com/carolynvs/magex/shx"
+	"github.com/stretchr/testify/require"
+)
+
+func TestLint(t *testing.T) {
+	test, err := tester.NewTest(t)
+	defer test.Close()
+	require.NoError(t, err, "test setup failed")
+
+	// When a mixin doesn't support lint, we should not print that to the console unless we are in debug mode
+	_, output, _ := test.RunPorterWith(func(cmd *shx.PreparedCommand) {
+		cmd.Args("lint")
+		// mybuns uses the testmixin which doesn't support lint
+		cmd.In(filepath.Join(test.RepoRoot, "tests/testdata/mybuns"))
+		// change verbosity to debug so that we see the error
+		cmd.Env("PORTER_VERBOSITY=debug")
+	})
+	require.Contains(t, output, "unknown command", "an unsupported mixin command should print to the console in debug")
+
+	_, output, _ = test.RunPorterWith(func(cmd *shx.PreparedCommand) {
+		cmd.Args("lint")
+		// mybuns uses the testmixin which doesn't support lint
+		cmd.In(filepath.Join(test.RepoRoot, "tests/testdata/mybuns"))
+		// errors are printed at the debug level to bump it up to info
+		cmd.Env("PORTER_VERBOSITY=info")
+	})
+	require.NotContains(t, output, "unknown command", "an unsupported mixin command should not be printed to the console in info")
+
+}