Add check config integration test

test/integration/dutagent/checkconfig_test.go

@@ -0,0 +1,103 @@
+// Copyright 2025 Blindspot Software
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package dutagent_integration contains integration tests for the dutagent binary.
+package dutagent_integration
+
+import (
+	"bytes"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"runtime"
+	"testing"
+)
+
+func TestMain(m *testing.M) {
+	bin, err := buildDutagent()
+	if err != nil {
+		os.Stderr.WriteString("failed to build dutagent: " + err.Error() + "\n")
+		os.Exit(1)
+	}
+
+	os.Setenv("DUTAGENT_TEST_BINARY", bin)
+
+	code := m.Run()
+	os.Remove(bin)
+	os.Exit(code)
+}
+
+func dutagentBinary(t *testing.T) string {
+	t.Helper()
+
+	bin := os.Getenv("DUTAGENT_TEST_BINARY")
+	if bin == "" {
+		t.Fatal("DUTAGENT_TEST_BINARY not set — was TestMain skipped?")
+	}
+
+	return bin
+}
+
+func buildDutagent() (string, error) {
+	bin, err := os.CreateTemp("", "dutagent-test-*")
+	if err != nil {
+		return "", err
+	}
+
+	bin.Close()
+
+	cmd := exec.Command("go", "build", "-o", bin.Name(), "../../../cmds/dutagent")
+	cmd.Stdout = os.Stderr
+	cmd.Stderr = os.Stderr
+
+	if err := cmd.Run(); err != nil {
+		return "", err
+	}
+
+	return bin.Name(), nil
+}
+
+func exampleConfigs(t *testing.T) []string {
+	t.Helper()
+
+	// Resolve relative to this source file so the test works regardless of
+	// working directory (e.g. go test ./...).
+	_, thisFile, _, _ := runtime.Caller(0)
+	root := filepath.Join(filepath.Dir(thisFile), "..", "..", "..")
+
+	configs, err := filepath.Glob(filepath.Join(root, "pkg", "module", "*", "*-example-cfg.yml"))
+	if err != nil {
+		t.Fatalf("glob failed: %v", err)
+	}
+
+	if len(configs) == 0 {
+		t.Fatal("no example config files found — check the glob pattern")
+	}
+
+	return configs
+}
+
+// TestCheckConfigExampleFiles runs dutagent --check-config against every example
+// config file shipped with the module packages and asserts:
+//   - exit code 0
+//   - "Configuration is valid" in output
+func TestCheckConfigExampleFiles(t *testing.T) {
+	bin := dutagentBinary(t)
+
+	for _, cfgPath := range exampleConfigs(t) {
+		t.Run(filepath.Base(filepath.Dir(cfgPath)), func(t *testing.T) {
+			cmd := exec.CommandContext(t.Context(), bin, "--check-config", "-c", cfgPath)
+			out, err := cmd.CombinedOutput()
+
+			if err != nil {
+				t.Errorf("unexpected exit: %v\n%s", err, out)
+				return
+			}
+
+			if !bytes.Contains(out, []byte("Configuration is valid")) {
+				t.Errorf("expected 'Configuration is valid' in output, got:\n%s", out)
+			}
+		})
+	}
+}