test/system: Add tests for failures for 'root'

https://github.com/containers/toolbox/pull/915

test/system/100-root.bats

@@ -0,0 +1,22 @@
+#!/usr/bin/env bats
+
+load 'libs/bats-support/load'
+load 'libs/bats-assert/load'
+load 'libs/helpers'
+
+setup() {
+  check_xdg_runtime_dir
+  cleanup_containers
+}
+
+teardown() {
+  cleanup_containers
+}
+
+@test "root: Try to enter the default container with no containers created" {
+  run $TOOLBOX <<< "n"
+
+  assert_success
+  assert_line --index 0 "No toolbox containers found. Create now? [y/N] A container can be created later with the 'create' command."
+  assert_line --index 1 "Run 'toolbox --help' for usage."
+}