The first time you run Infection for your project, it will ask you several questions to create a config file infection.json.dist, with the following structure:

"source": {
"directories": [
"excludes": [
"timeout": 10,
"logs": {
"text": "infection.log",
"summary": "summary.log",
"json": "infection-log.json",
"perMutator": "",
"github": true,
"badge": {
"branch": "master"
"tmpDir": "/opt/tmp-folder",
"phpUnit": {
"configDir": "app",
"customPath": "\/path\/to\/phpunit-6.1.phar"
"mutators": {
"global-ignore": [
"global-ignoreSourceCodeByRegex": [
"@default": true,
"@function_signature": false,
"TrueValue": {
"ignore": [
"ignoreSourceCodeByRegex": [
"initialTestsPhpOptions": "-d",
"testFrameworkOptions": "-vvv"

You can commit it to the VCS and, if necessary, override it locally by creating infection.json which should be ignored (e.g. in .gitignore).

Configuration settings

How to use custom autoloader or bootstrap file

If you have a custom autoloader or bootstrap file for your application, you should tell Infection about it.

For example you have

// custom-autoloader.php

require NonPsr4CompliantFile.php

then you have to add it to the infection.json file:

"bootstrap": "./custom-autoloader.php"

Thus, Infection will know how to autoload NonPsr4CompliantFile class. Without adding it to the config, Infection will not be able to create Mutations because internally it uses new \ReflectionClass() objects.

Running Infection

Ensure that your tests are all in a passing state (incomplete and skipped tests are allowed). Infection will quit if any of your tests are failing.

If you have installed Infection as a global composer package, just run it in your project’s root:


or if you cloned it to some folder:

# cd /path/to/project/root


Running with Xdebug

In order to run Infection with Xdebug, you have several options:

Enable Xdebug globally

In this case just run

./infection.phar --threads=4

Enable Xdebug per process

Since Infection needs Xdebug only to generate code coverage in a separate process, it is possible to enable debugger just there.

Assuming Xdebug is disabled globally, run

./infection.phar --initial-tests-php-options="-d"

Running with phpdbg

In order to run Infection with phpdbg instead of Xdebug, you need to execute the following command:

phpdbg -qrr infection.phar

Running without debugger

It is possible to run Infection without any debugger enabled. However, in this case you should provide already generated code coverage as an option

./infection.phar --coverage=path/to/coverage

Read more what types of coverage Infection requires and how to do it.

Using with PHPUnit

@codeCoverageIgnore support

Infection supports @codeCoverageIgnore annotation on class and method level.

The following class will not be mutated, because it does not produce any code coverage.

* @codeCoverageIgnore
class Calculator
public function add(float $a, float $b): float
return $a + $b;

In this example, method generate() will be skipped from mutation logic, but getDependencies() will be mutated as usual method.

class ProductFixture
* @codeCoverageIgnore
public function generate(): void
// generate logic

public function getDependencies(): array
return [CategoryFixture::class];

Exposed environment variables

Infection exposes a couple of environment variables: