Add generate-config command to output default configuration in YAML format

cmd/scratchbox/main_test.go

@@ -19,6 +19,7 @@ import (
 	"scratchbox/internal/config"
 	httpapi "scratchbox/internal/http"
 	"scratchbox/internal/storage"
+	"gopkg.in/yaml.v3"
 )
 
 func repoRoot(t *testing.T) string {
@@ -205,6 +206,55 @@ func TestMainHelperProcess(t *testing.T) {
 	}
 }
 
+func TestGenerateConfigCommandWritesDefaultYAML(t *testing.T) {
+	t.Parallel()
+
+	cmd := newRootCmd()
+	var out bytes.Buffer
+	cmd.SetOut(&out)
+	cmd.SetErr(io.Discard)
+	cmd.SetArgs([]string{"generate-config"})
+
+	if err := cmd.Execute(); err != nil {
+		t.Fatalf("Execute() error = %v", err)
+	}
+
+	if out.Len() == 0 {
+		t.Fatalf("generate-config output is empty")
+	}
+
+	var cfg config.Config
+	if err := yaml.Unmarshal(out.Bytes(), &cfg); err != nil {
+		t.Fatalf("yaml.Unmarshal() error = %v", err)
+	}
+
+	if cfg.Server.ListenAddr != ":8080" {
+		t.Fatalf("server.listen_addr = %q, want %q", cfg.Server.ListenAddr, ":8080")
+	}
+	if cfg.Limits.MaxUploadSize != "100MB" {
+		t.Fatalf("limits.max_upload_size = %q, want %q", cfg.Limits.MaxUploadSize, "100MB")
+	}
+	if cfg.Storage.DataDir != "./data" {
+		t.Fatalf("storage.data_dir = %q, want %q", cfg.Storage.DataDir, "./data")
+	}
+	if cfg.Security.RateLimit.RequestsPerMinute != 30 {
+		t.Fatalf("security.rate_limit.requests_per_minute = %d, want %d", cfg.Security.RateLimit.RequestsPerMinute, 30)
+	}
+}
+
+func TestGenerateConfigCommandRejectsUnexpectedArgs(t *testing.T) {
+	t.Parallel()
+
+	cmd := newRootCmd()
+	cmd.SetOut(io.Discard)
+	cmd.SetErr(io.Discard)
+	cmd.SetArgs([]string{"generate-config", "extra"})
+
+	if err := cmd.Execute(); err == nil {
+		t.Fatalf("expected error for unexpected args")
+	}
+}
+
 func TestLiveServerEndToEndHTTP(t *testing.T) {
 	tmp := t.TempDir()
 	cfgPath := filepath.Join(tmp, "config.yaml")