I have become prone to fungal & viral infection. can you suggest which type of immunity test should be done to check immunity strength like igg1, etc.

See Immunologist: As a generality, T-cell dysfunction (and not B-cell or lack of antibody production) could potentially lead to susceptibility for viral and fungal infections. One might start by checking lymphocyte subpopulations and T-cell function as an initial work-up.

Not just a test: but an evaluation by an experienced immunologist , you might not have a primary immune deficiency, may be just a transit condition causing secondary immune deficiency due to a drug or virus infection, so history, drug history, physical examination are important for evaluation, look for an expert in the field, meanwhile check cbcd, total IgG, IgE, IgA & IgM, + T&B lymphocytes flowcytometry,