feat: add shell login option (#75)

Closes #72

root/shell_args_test.go

@@ -0,0 +1,35 @@
+package root
+
+import (
+	"reflect"
+	"testing"
+)
+
+func TestShellArgs(t *testing.T) {
+	tests := []struct {
+		name  string
+		login bool
+		want  []string
+	}{
+		{name: "login", login: true, want: []string{"--login"}},
+		{name: "non-login", login: false},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := shellArgs(tt.login); !reflect.DeepEqual(got, tt.want) {
+				t.Fatalf("shellArgs(%v) = %v, want %v", tt.login, got, tt.want)
+			}
+		})
+	}
+}
+
+func TestShellLoginFlagIsRegistered(t *testing.T) {
+	flag := rootCmd.PersistentFlags().Lookup("shell-login")
+	if flag == nil {
+		t.Fatal("expected --shell-login flag to be registered")
+	}
+	if flag.DefValue != "false" {
+		t.Fatalf("expected --shell-login to default to false, got %q", flag.DefValue)
+	}
+}