@Test
    public void registersTraitValidators() {
        ValidatedResult<Model> result = new ModelAssembler()
                .addImport(getClass().getResource("errors.json"))
                .assemble();

        assertThat(result.getValidationEvents(), hasSize(2));
        assertThat(result.getValidationEvents().get(0).getMessage(), containsString("client"));
        assertThat(result.getValidationEvents().get(1).getMessage(), containsString("server"));
    }
This test exercises ModelValidator but done so using the ModelAssembler.
smithy-model/src/test/java/software/amazon/smithy/model/loader/ModelValidatorTest.java