@Test
    public void attributeExistence_MatchesShapesWithProjection() {
        // Empty projections don't exist.
        assertThat(SelectorTest.exampleIds(attributeExistenceModel, "[trait|tags|(values)]"), empty());

        // An empty projection does not exist.
        assertThat(SelectorTest.exampleIds(attributeExistenceModel, "[trait|enum|(values)]"),
                containsInAnyOrder("smithy.example#MyString3",
                        "smithy.example#MyString4",
                        "smithy.example#MyString5"));

        assertThat(SelectorTest.exampleIds(attributeExistenceModel, "[trait|enum|(values)|tags]"),
                containsInAnyOrder("smithy.example#MyString5"));

        // An empty projection does not exist.
        assertThat(SelectorTest.exampleIds(attributeExistenceModel, "[trait|enum|(values)|tags|(values)]"),
                containsInAnyOrder("smithy.example#MyString5"));
    }
This is a kind of integration test of the examples in the
specification.

Each test "category" is prefixed with "[name]_" to group them.

TODO: It would be great to consolidate other tests from SelectorTest here to better organize tests.
smithy-model/src/test/java/software/amazon/smithy/model/selector/SpecIntegTest.java