    @Test
    public void testBuildScopeString() {

        ConsumerKey ck = new ConsumerKey("ck-abc", "ck-123");
        FlattrAuthenticator auth = new FlattrAuthenticator(ck);

        auth.getScope().add(Scope.FLATTR);
        assertThat(auth.buildScopeString(), is("flattr"));

        auth.getScope().add(Scope.THING);
        assertThat(auth.buildScopeString(), is("flattr thing"));

        auth.getScope().clear();
        assertThat(auth.buildScopeString(), isEmptyString());

        auth.setScope(EnumSet.allOf(Scope.class));
        assertThat(auth.buildScopeString(), is("flattr thing email extendedread"));

        auth.setScope(EnumSet.noneOf(Scope.class));
        assertThat(auth.buildScopeString(), isEmptyString());
    }