TEST(QueryProjectionTest, MakeSingleFieldInclusion) {
    Projection proj(createProjection("{}", "{a: 1}"));
    ASSERT_FALSE(proj.requiresDocument());
    const auto& fields = proj.getRequiredFields();
    ASSERT_EQUALS(fields.size(), 2U);
    ASSERT_EQUALS(fields[0], "_id");
    ASSERT_EQUALS(fields[1], "a");
}
TEST(QueryProjectionTest, MakeSingleFieldInclusion) {
    Projection proj(createProjection("{}", "{a: 1}"));
    ASSERT_FALSE(proj.requiresDocument());
    const auto& fields = proj.getRequiredFields();
    ASSERT_EQUALS(fields.size(), 2U);
    ASSERT_EQUALS(fields[0], "_id");
    ASSERT_EQUALS(fields[1], "a");
}