TEST(ComparisonMatchExpression, StringMatchingWithNullCollatorUsesBinaryComparison) {
    BSONObj operand = BSON("a"
                           << "string");
    EqualityMatchExpression eq;
    ASSERT(eq.init("a", operand["a"]).isOK());
    ASSERT(!eq.matchesBSON(BSON("a"
                                << "string2"),
                           NULL));
}
TEST(ComparisonMatchExpression, StringMatchingWithNullCollatorUsesBinaryComparison) {
    BSONObj operand = BSON("a"
                           << "string");
    EqualityMatchExpression eq;
    ASSERT(eq.init("a", operand["a"]).isOK());
    ASSERT(!eq.matchesBSON(BSON("a"
                                << "string2"),
                           NULL));
}