add theming

cmd/root_test.go

@@ -0,0 +1,17 @@
+package cmd
+
+import "testing"
+
+func TestValidateTheme_Valid(t *testing.T) {
+	for _, name := range []string{"cyberpunk", "purplerain", "cactus"} {
+		if err := validateTheme(name); err != nil {
+			t.Errorf("validateTheme(%q) unexpected error: %v", name, err)
+		}
+	}
+}
+
+func TestValidateTheme_Invalid(t *testing.T) {
+	if err := validateTheme("not-a-theme"); err == nil {
+		t.Error("expected error for unrecognized theme name")
+	}
+}