@Test
public void stringInvalidInput() {

    TestResourceBundle bundle = new TestResourceBundle();
    bundle.getResourcesMap().put("test.key", "'foo'");
    Resources resources = new Resources(bundle);
    assertThatExceptionOfType(NullPointerException.class).isThrownBy(() -> resources.string(null));
    assertThatExceptionOfType(MissingResourceException.class).isThrownBy(() -> resources.string("missing.key"));
}