mongo/jstests/core/dbcase2.js

// SERVER-2111 Check that an in memory db name will block creation of a db with a similar but differently cased name.

var dbLowerCase = db.getSisterDB( "dbcase2test_dbnamea" )
var dbUpperCase = db.getSisterDB( "dbcase2test_dbnameA" )

var resultLower = dbLowerCase.c.insert({});
assert.eq(1, resultLower.nInserted);

var resultUpper = dbUpperCase.c.insert({});
assert.eq(0, resultUpper.nInserted);
assert.writeError(resultUpper);

assert.eq( -1, db.getMongo().getDBNames().indexOf( "dbcase2test_dbnameA" ) );