var res = db.isMaster();
// check that the fields that should be there are there and have proper values
assert( res.maxBsonObjectSize &&
        isNumber(res.maxBsonObjectSize) &&
        res.maxBsonObjectSize > 0, "maxBsonObjectSize possibly missing:" + tojson(res));
assert( res.maxMessageSizeBytes &&
        isNumber(res.maxMessageSizeBytes) &&
        res.maxBsonObjectSize > 0, "maxMessageSizeBytes possibly missing:" + tojson(res));
assert(res.ismaster, "ismaster missing or false:" + tojson(res));
assert(res.localTime, "localTime possibly missing:" + tojson(res));
var unwantedFields = ["setName", "setVersion", "secondary", "hosts", "passives", "arbiters",
                      "primary", "aribterOnly", "passive", "slaveDelay", "hidden", "tags",
                      "buildIndexes", "me"];
// check that the fields that shouldn't be there are not there
var badFields = [];
for (field in res) {
    if (!res.hasOwnProperty(field)){
        continue;
    }
    if (Array.contains(unwantedFields, field)) {
        badFields.push(field);
    }
}
assert(badFields.length === 0, "\nthe result:\n" + tojson(res)
                             + "\ncontained fields it shouldn't have: " + badFields);