refactored overlay class

overlay.GetOverlay(name) returns now an error if the overlay doesn't
exist. This is the most canonical way to act if there is no overlay.

internal/app/wwctl/overlay/mkdir/main_test.go

@@ -0,0 +1,89 @@
+package mkdir
+
+import (
+	"bytes"
+	"io/fs"
+	"os"
+	"path/filepath"
+	"strconv"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/warewulf/warewulf/internal/pkg/testenv"
+	"github.com/warewulf/warewulf/internal/pkg/warewulfd"
+)
+
+func Test_OverlayMkdir(t *testing.T) {
+	tests := []struct {
+		name        string
+		overlayName string
+		dirName     string
+		perm        string
+		wantErr     bool
+		system      bool
+	}{
+		{
+			name:        "simple mkdir",
+			overlayName: "test-overlay",
+			dirName:     "testdir",
+			perm:        "0755",
+			wantErr:     false,
+			system:      false,
+		},
+		{
+			name:        "system overlay mkdir",
+			overlayName: "wwinit", // A known system overlay
+			dirName:     "init.d",
+			perm:        "0700",
+			wantErr:     false,
+			system:      true,
+		},
+	}
+
+	warewulfd.SetNoDaemon()
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			env := testenv.New(t)
+			conf := env.Configure()
+
+			// Setup overlay
+			var overlayDir string
+			if tt.system {
+				overlayDir = filepath.Join(conf.Paths.DistributionOverlaydir(), tt.overlayName)
+				err := os.MkdirAll(overlayDir, 0755)
+				assert.NoError(t, err)
+			} else {
+				overlayDir = filepath.Join(conf.Paths.WWOverlaydir, tt.overlayName)
+				err := os.MkdirAll(overlayDir, 0755)
+				assert.NoError(t, err)
+			}
+
+			baseCmd := GetCommand()
+			baseCmd.SetArgs([]string{"-m", tt.perm, tt.overlayName, tt.dirName})
+			buf := new(bytes.Buffer)
+			baseCmd.SetOut(buf)
+			baseCmd.SetErr(buf)
+			err := baseCmd.Execute()
+
+			if tt.wantErr {
+				assert.Error(t, err)
+			} else {
+				assert.NoError(t, err)
+			}
+
+			// Check permissions
+			// for system overlays, the file is copied to a site overlay
+			if tt.system {
+				overlayDir = filepath.Join(conf.Paths.WWOverlaydir, tt.overlayName)
+			}
+			dirPath := filepath.Join(overlayDir, tt.dirName)
+			stat, err := os.Stat(dirPath)
+			assert.NoError(t, err)
+			if !tt.wantErr {
+				mode, err := strconv.ParseUint(tt.perm, 8, 32)
+				assert.NoError(t, err)
+				assert.Equal(t, fs.FileMode(mode), stat.Mode().Perm())
+			}
+		})
+	}
+}