Infection PHP 0.6.2 Released

Infection PHP is an AST based (Abstract Syntax Tree) PHP Mutation Testing Framework. From the documentation “Mutation Testing is a fault-based testing technique which provides a testing criterion called the Mutation Score Indicator (MSI). The MSI can be used to measure the effectiveness of a test set in terms of its ability to detect faults.”

The framework which works as a CLI tool allow to runs the test suit, mutates the source code with a set of predefined mutators (mutation operators), and collects the results of killed, escaped mutants and timeouts.

For example, given you have a Form class with hasErrors() method :

// Form.php
public function hasErrors(): bool
{
    return count($this->errors) > 0;
}

Infection will create the following mutants:

• Conditional boundary mutator

public function hasErrors(): bool
{
-    return count($this->errors) > 0;
+    return count($this->errors) >= 0;
}

• Conditional negotiation mutator

public function hasErrors(): bool
{
-    return count($this->errors) > 0;
+    return count($this->errors) < 0;
}

• and Integer 0-1, 1-0 mutator

public function hasErrors(): bool
{
-    return count($this->errors) > 0;
+    return count($this->errors) > 1;
}

The mutation score will be :

• Mutation Score Indicator (MSI): 47%
• Mutation Code Coverage (MCC): 67%
• Covered Code MSI: 70%