Software testing is crucial in ensuring that computer code works as intended. This paper introduces fuzzy theory to white box testing, where testers have full knowledge of the code. By using fuzzy theory, testers can now determine the degree of acceptance or rejection of software, providing flexibility in the testing process. The paper integrates fuzzy theory with various white box testing techniques like dataflow testing, control flow testing, and path testing to improve the accuracy of testing outcomes. Glassbox testing techniques are highlighted as effective in identifying errors and validating software design.