If you are asking for only class test of 12 in Physics, Chemistry and Mathematics, then you can just prepare from NCERTs. Class tests are taken to check if students are studying at home or not, whether they are understanding the subjects. Tough or complex questions are not usually asked in Class tests. You can prepare for it if you thoroughly study NCERT Textbooks. NCERTs are the best study material written in simple language understandable to everyone. If you want to do complex problems, want to know in depth, you can surely follow some standard reference books like Concept of Physics by HC Verma for Physics, one of the best books for Physics having a number of quality problems in all the topics. For Chemistry, you can rely on Concept of Physical Chemistry by P Bahadur and Chemical Calculations by RC Mukherjee, the latter has many numerical problems to solve. And you can prepare frp Organic chemistry from NCERTs. Understand the mechanism first then by rewriting the equations get a grip on them. Solve problems from Objective Mathematics by R D Sharma.