Masking occurs when one condition prevents another condition from influencing the output of a Boolean expression. Logic-based adequacy criteria such as Multiple Condition Coverage (MCC) are designed to overcome masking at the within-expression level, but can offer no guarantees about masking in subsequent expressions. As a result, a Boolean expression written as a single complex statement will yield test cases that are more likely to overcome masking than when the expression is written as series of simple statements. Many approaches to automated analysis and test case generation for Java systems operate not on the source code representation of code, but on the bytecode. The transformation from source code to bytecode requires simplifying code elements, introducing the risk of masking. We propose Bytecode-MCC, designed to group related Boolean expressions from the bytecode, reformulate the expressions into a single complex expression, and produce test cases satisfying each combination of conditions in the constructed expression. Bytecode-MCC should produce test obligations that---when satisfied---are more likely to reveal faults in the program logic than tests providing coverage of existing criteria over the simplified bytecode.

A preliminary study has hinted at the potential of this approach. However, Bytecode-MCC is more difficult to achieve than Branch Coverage and means of increasing coverage are needed to truly test the fault-detection potential of this technique. We propose methods of improving Bytecode-MCC coverage through automated generation that we will explore in future work.