• Exploratory testing automation. Now, Bacterio is able to catch mouse and keyboard events and store them as a Bacterio format test case. Then, these events can be reproduced with mutants to calculate the mutation score. This is excellent way to measure the quality of your exploratory test cases.
• Mutant schema implemented. In the new version, Bacterio implements mutant schema technique, which reduces the requirements to store mutants and speed up the execution of them. This makes Bacterio faster and more efficient.
• Some types of mutation. In the previous version Bacterio only implemented Flexible Weak Mutation. The new version also implements Strong mutation, BB-Weak/1 mutation and BB-Weak/N mutation. Each mutation type has different effectiveness/efficiency relation,thus it gives the testers more flexibility in their test projects.
• Execution time storage. This new version of Bacterio is able to store generation and execution times. This valuable information can be used to estimate costs in future testing projects.
• Parallel execution. As the execution of mutants has high computational requirements, the new version of Bacterio implements two new modules that allow testers to execute mutants in some computers concurrently, whit the only requirement that all computer has to be in the same network (they don’t need any special operative system).
• Equivalent mutants detection assistance. The new version of Bacterio assists testers in the identification of equivalent mutants. Bacterio compare the code of the original system and each mutant and the differences found are showed in colors.

BACTERIO Mutation Test System is a tool for testing complete Java systems. It generates copies of the application and introduces one or more faults in each one. Then, a test suite consisting of JUnit or UISpec test cases can be executed against the original and the mutants versions. When a test suite doen't find faults in the original system but it does find the seeded faults in the mutant versions, it can be assured that the system has been successfully tested, since the test suite is complete, it doesn't detect faults on the original system, and it kills a high percentage of mutants.

The next figure sums up the mutation-based testing process with the tool BACTERIO Mutation test System:

The testing process with BACTERIO Mutation Test System comprises the following steps:

1. Mutant generation

In this first step, BACTERIO Mutation Test System generates faulty copies (mutants) of the classes of the system under test. In order to do that, it provides several mutation operators: arithmetic operator replacement, parameter swapping, operator increase, operator decrease, etc.

2. Mutant combination

In this second step, BACTERIO Mutation Test provides three algorithms (one mutant per version, using each mutant at least once, and using every pair of mutants) to combine the mutants and generate faulty versions.

3. Test Case Execution

In the last step, BACTERIO Mutation Test System executes the test cases against the different faulty versions.  Then, it provides the percentage of killed mutants, and, therefore, the coverage reached with the designed test suite.