at the end of the day, it was inevitable

behat/Command/Util/CommandTest.php

@@ -0,0 +1,85 @@
+<?php
+
+namespace Command\Util;
+
+use Symfony\Bundle\FrameworkBundle\Console\Application;
+use Symfony\Component\Console\Input\ArrayInput;
+use Symfony\Component\Console\Input\InputInterface;
+use Symfony\Component\Console\Output\BufferedOutput;
+
+/**
+ * Class CommandTest
+ * @package Command\Util
+ */
+class CommandTest
+{
+
+    /**
+     * @var Application
+     */
+    private $application;
+
+    /**
+     * @var InputInterface
+     */
+    private $input;
+
+    /**
+     * @var BufferedOutput
+     */
+    private $output;
+
+    /**
+     * @var integer
+     */
+    private $exitCode;
+
+    /**
+     * Command constructor.
+     *
+     * @param Application $application A Application instance.
+     * @param string      $command     Command name.
+     * @param array       $params      Command parameters.
+     */
+    public function __construct(
+        Application $application,
+        $command,
+        array $params = []
+    ) {
+        $this->application = $application;
+        $this->input = new ArrayInput([ 'command' => $command ] + $params);
+    }
+
+    /**
+     * Run this command.
+     *
+     * @return CommandTest
+     */
+    public function run()
+    {
+        $this->output = new BufferedOutput();
+        $this->exitCode = $this->application->run($this->input, $this->output);
+
+        return $this;
+    }
+
+    /**
+     * Get exit code.
+     *
+     * @return integer
+     */
+    public function getExitCode()
+    {
+        return $this->exitCode;
+    }
+
+    /**
+     * Get output.
+     *
+     * @return string
+     */
+    public function getOutput()
+    {
+        return $this->output->fetch();
+    }
+}

behat/Command/Util/CommandTestFactory.php

@@ -0,0 +1,45 @@
+<?php
+
+namespace Command\Util;
+
+use Symfony\Bundle\FrameworkBundle\Console\Application;
+use Symfony\Component\HttpKernel\KernelInterface;
+
+/**
+ * Class CommandTestFactory
+ * @package Command\Util
+ */
+class CommandTestFactory
+{
+
+    /**
+     * @var Application
+     */
+    private $application;
+
+    /**
+     * CommandRunner constructor.
+     *
+     * @param KernelInterface $kernel A KernelInterface instance.
+     */
+    public function __construct(KernelInterface $kernel)
+    {
+        $this->application = new Application($kernel);
+        // If don't set to false, application will call 'exit' after command was
+        // executed.
+        $this->application->setAutoExit(false);
+    }
+
+    /**
+     * Create new command instance.
+     *
+     * @param string $command Command name.
+     * @param array  $params  Command parameters.
+     *
+     * @return CommandTest
+     */
+    public function create($command, array $params = [])
+    {
+        return new CommandTest($this->application, $command, $params);
+    }
+}