To answer this question, we need to understand the difference between black-box testing and white-box testing.
Black-box testing is a type of testing technique where the internal structure, design, and implementation details of the system under test are not known to the tester. In black-box testing, the tester focuses on testing the functionality of the system without any knowledge of the internal workings of the system. This type of testing is primarily based on requirements and specifications.
White-box testing, on the other hand, is a type of testing technique where the tester has full knowledge of the internal structure, design, and implementation details of the system under test. In white-box testing, the tester can examine the code, data structures, and algorithms to identify potential issues and validate the system against internal behaviors and logic.
Now, let's go through each option to understand which types of errors can be uncovered by white-box testing but missed by black-box testing:
A. Behavioral errors - Black-box testing is focused on testing the behavior of the system based on the input and expected output. It may uncover behavioral errors, so this option is incorrect.
B. Logic errors - White-box testing, with its knowledge of the internal structure and implementation details, can identify logical flaws in the code and algorithms. It can uncover logic errors that may not be detected through black-box testing. This option is correct.
C. Performance errors - Performance errors, such as issues with response time or resource utilization, are typically not related to the internal structure or implementation details. They are more related to the overall system configuration and environment. Both black-box and white-box testing can potentially uncover performance errors. This option is incorrect.
D. Typographical errors - Typographical errors, such as spelling mistakes or syntax errors, are related to the correctness of the code or documentation. White-box testing can uncover typographical errors by examining the code and documentation. Black-box testing may not specifically focus on these types of errors. This option is correct.
Based on the explanations above, we can conclude that option E ("Both b and d") is the correct answer. White-box testing can uncover logic errors (option B) and typographical errors (option D) that may be missed by black-box testing.