Command Line Options

Besides general Symfony Console application command line options, Infection has its own ones.


If you’re only interested in mutating a subset of your files, you can pass a --filter option containing:

This in no way restricts the initial Infection check on the overall test suite which is still executed in full to ensure all tests are passing correctly before proceeding.

--threads or -j

If you want to run tests for mutated code in parallel, set this to something > 1. It will dramatically speed up mutation process. Please note that if your tests somehow depends on each other or use database, this option can lead to failing tests which give many false-positives results.

On most platforms where GNU coreutils are available, which includes all variants of Linux, there is nproc command that returns the number of processors available. It can be used as such to let Infection run at the full speed:

# on Linux
infection -j$(nproc)

# on OSX
infection -j$(sysctl -n hw.ncpu)


This is a name of the Test framework to use. Currently Infection supports PHPUnit and PhpSpec.

Feel free to request a new test framework to be supported out of the box in Github’s issues.


This options allows to pass additional options to the test framework. Example for PHPUnit:

infection.phar --test-framework-options="--verbose --filter=just/unit/tests"

This will execute the phpunit as:

phpunit [...infection options] --verbose --filter=just/unit/tests

Please note that if you choose to use --filter and --testsuite for PHPUnit, these options will only be applied to the initial test run. Each mutation has a custom phpunit.xml file generated for it which defines a single testsuite containing the tests which should be executed for that mutation. Applying --filter or --testsuite would not make sense in this context as the tests have already been filtered down.


Path to the existing coverage reports.

When you use Continuous Integration for your project, probably you are already generating code coverage metrics and run PHPUnit with XDebug/phpdbg enabled. Then, you run Infection for mutation testing, which in its turn, generates Code Coverage again for internal needs. This dramatically increases the build time because running your tests with debugger twice requires too much time.

With this option it’s possible to reuse already generated coverage in Infection.

For PHPUnit:

For PhpSpec:


# collect coverage
vendor/bin/phpunit --coverage-xml=build/coverage/coverage-xml --log-junit=build/coverage/phpunit.junit.xml

# use coverage
infection.phar --coverage=build/coverage


Run the mutation testing only for covered by tests files.

--show-mutations or -s

Show colorized diffs of mutated files to the console.

Please note that all mutations are logged to the infection.log file as well.

--configuration or -c

If you want to use custom configuration file path or name, use this option for it.


This is a minimum threshold of Mutation Score Indicator (MSI) in percentage. Can be used with CI server to automatically control tests quality.

Read more about using Infection in CI server


This is a minimum threshold of Covered Code Mutation Score Indicator (MSI) in percentage. Can be used with CI server to automatically control tests quality.


This is a comma separated option to specify a particular set of mutators or profiles that need to be executed. Example:

infection --mutators=PublicVisibility,Plus,Decrement,@number

See here to find all mutator names.


This is a name of console output formatter. Possible values are: dot, progress. Default is dot formatter.


The verbosity of the log file, debug - debug mode will add “Killed mutants” into log file and add additional information, default - normal mode will skip “Killed mutants” section in the log file, none - which will disable logging to files.

infection --log-verbosity=debug


Run Initial Tests process with additional php options. For example with -d which will run Xebug only for code coverage.
May be useful for cases when Xebug is not enabled globally. Also it’s useful from performance point of view.

infection --initial-tests-php-options="-d"


Ignore MSI violations when no mutations are generated. This will force Infection to return a zero exit code even when the required MSI is not reached.


Run Infection in a debug mode. With this option Infection will not erase tmpDir and this might be useful to run particular unit test with a mutated code for example.