@Test
public void shouldRegisterNewPrefixWithNewUri() throws Exception {

    String prefix = "foo";
    String uri = "http://example.com";
    assertThatNamespacePrefixIsNotRegistered(prefix);
    assertThatNamespaceUriIsNotRegistered(uri);
    registry.registerNamespace(prefix, uri);
    assertThatNamespaceIsRegistered(prefix, uri);
}