项目创建后自动创建的单元测试文件夹， 文件夹名为项目名+tests， xcode6后貌似没有选择是否添加测试target的选择了。
默认生成的如下图
提供的断言如下
typedefns_enum(nsuinteger, _xctassertiontype) {
_xctassertion_fail,
_xctassertion_nil,
_xctassertion_notnil,
_xctassertion_equalobjects,
_xctassertion_notequalobjects,
_xctassertion_equal,
_xctassertion_notequal,
_xctassertion_equalwithaccuracy,
_xctassertion_notequalwithaccuracy,
_xctassertion_greaterthan,
_xctassertion_greaterthanorequal,
_xctassertion_lessthan,
_xctassertion_lessthanorequal,
_xctassertion_true,
_xctassertion_false,
_xctassertion_throws,
_xctassertion_throwsspecific,
_xctassertion_throwsspecificnamed,
_xctassertion_nothrow,
_xctassertion_nothrowspecific,
_xctassertion_nothrowspecificnamed,
};