diff --git a/.ci/travis-functions.sh b/.ci/travis-functions.sh
index 98a9a1d8b..3a80314b6 100644
--- a/.ci/travis-functions.sh
+++ b/.ci/travis-functions.sh
@@ -32,4 +32,4 @@ function get-infection-pr-flags() {
     fi
 
     echo $INFECTION_PR_FLAGS;
-}
\ No newline at end of file
+}
diff --git a/src/Command/InfectionCommand.php b/src/Command/InfectionCommand.php
index 4a8cace01..fcc82a668 100644
--- a/src/Command/InfectionCommand.php
+++ b/src/Command/InfectionCommand.php
@@ -120,6 +120,12 @@ protected function configure(): void
                 InputOption::VALUE_NONE,
                 'Show mutations to the console'
             )
+            ->addOption(
+                'no-progress',
+                null,
+                InputOption::VALUE_NONE,
+                'Do not output progress bars'
+            )
             ->addOption(
                 'configuration',
                 'c',
diff --git a/src/Process/Builder/SubscriberBuilder.php b/src/Process/Builder/SubscriberBuilder.php
index 371e34f57..58e1eeaa4 100644
--- a/src/Process/Builder/SubscriberBuilder.php
+++ b/src/Process/Builder/SubscriberBuilder.php
@@ -41,11 +41,15 @@
 use Infection\Console\OutputFormatter\ProgressFormatter;
 use Infection\Differ\DiffColorizer;
 use Infection\EventDispatcher\EventDispatcherInterface;
+use Infection\EventDispatcher\EventSubscriberInterface;
 use Infection\Mutant\MetricsCalculator;
 use Infection\Performance\Listener\PerformanceLoggerSubscriber;
 use Infection\Performance\Memory\MemoryFormatter;
 use Infection\Performance\Time\TimeFormatter;
 use Infection\Performance\Time\Timer;
+use Infection\Process\Listener\CiInitialTestsConsoleLoggerSubscriber;
+use Infection\Process\Listener\CiMutantCreatingConsoleLoggerSubscriber;
+use Infection\Process\Listener\CiMutationGeneratingConsoleLoggerSubscriber;
 use Infection\Process\Listener\CleanUpAfterMutationTestingFinishedSubscriber;
 use Infection\Process\Listener\InitialTestsConsoleLoggerSubscriber;
 use Infection\Process\Listener\MutantCreatingConsoleLoggerSubscriber;
@@ -150,9 +154,9 @@ private function getSubscribers(
         OutputInterface $output
     ): array {
         $subscribers = [
-            new InitialTestsConsoleLoggerSubscriber($output, $testFrameworkAdapter),
-            new MutationGeneratingConsoleLoggerSubscriber($output),
-            new MutantCreatingConsoleLoggerSubscriber($output),
+            $this->getInitialTestsConsoleLoggerSubscriber($testFrameworkAdapter, $output),
+            $this->getMutantGeneratingConsoleLoggerSubscriber($output),
+            $this->getMutantCreatingConsoleLoggerSubscriber($output),
             new MutationTestingConsoleLoggerSubscriber(
                 $output,
                 $this->getOutputFormatter($output),
@@ -199,4 +203,38 @@ private function getOutputFormatter(OutputInterface $output): OutputFormatter
 
         throw new \InvalidArgumentException('Incorrect formatter. Possible values: "dot", "progress"');
     }
+
+    private function getMutantCreatingConsoleLoggerSubscriber(OutputInterface $output): EventSubscriberInterface
+    {
+        if ($this->shouldSkipProgressBars()) {
+            return new CiMutantCreatingConsoleLoggerSubscriber($output);
+        }
+
+        return new MutantCreatingConsoleLoggerSubscriber($output);
+    }
+
+    private function getMutantGeneratingConsoleLoggerSubscriber(OutputInterface $output): EventSubscriberInterface
+    {
+        if ($this->shouldSkipProgressBars()) {
+            return new CiMutationGeneratingConsoleLoggerSubscriber($output);
+        }
+
+        return new MutationGeneratingConsoleLoggerSubscriber($output);
+    }
+
+    private function getInitialTestsConsoleLoggerSubscriber(AbstractTestFrameworkAdapter $testFrameworkAdapter, OutputInterface $output): EventSubscriberInterface
+    {
+        if ($this->shouldSkipProgressBars()) {
+            return new CiInitialTestsConsoleLoggerSubscriber($output, $testFrameworkAdapter);
+        }
+
+        return new InitialTestsConsoleLoggerSubscriber($output, $testFrameworkAdapter);
+    }
+
+    private function shouldSkipProgressBars(): bool
+    {
+        return $this->input->getOption('no-progress')
+            || getenv('CI') === 'true'
+            || getenv('CONTINUOUS_INTEGRATION') === 'true';
+    }
 }
diff --git a/src/Process/Listener/CiInitialTestsConsoleLoggerSubscriber.php b/src/Process/Listener/CiInitialTestsConsoleLoggerSubscriber.php
new file mode 100644
index 000000000..b41a89658
--- /dev/null
+++ b/src/Process/Listener/CiInitialTestsConsoleLoggerSubscriber.php
@@ -0,0 +1,89 @@
+<?php
+/**
+ * This code is licensed under the BSD 3-Clause License.
+ *
+ * Copyright (c) 2017-2019, Maks Rafalko
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * * Redistributions of source code must retain the above copyright notice, this
+ *   list of conditions and the following disclaimer.
+ *
+ * * Redistributions in binary form must reproduce the above copyright notice,
+ *   this list of conditions and the following disclaimer in the documentation
+ *   and/or other materials provided with the distribution.
+ *
+ * * Neither the name of the copyright holder nor the names of its
+ *   contributors may be used to endorse or promote products derived from
+ *   this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+declare(strict_types=1);
+
+namespace Infection\Process\Listener;
+
+use Infection\EventDispatcher\EventSubscriberInterface;
+use Infection\Events\InitialTestSuiteStarted;
+use Infection\TestFramework\AbstractTestFrameworkAdapter;
+use Symfony\Component\Console\Output\OutputInterface;
+
+/**
+ * @internal
+ */
+final class CiInitialTestsConsoleLoggerSubscriber implements EventSubscriberInterface
+{
+    /**
+     * @var OutputInterface
+     */
+    private $output;
+
+    /**
+     * @var AbstractTestFrameworkAdapter
+     */
+    private $testFrameworkAdapter;
+
+    public function __construct(OutputInterface $output, AbstractTestFrameworkAdapter $testFrameworkAdapter)
+    {
+        $this->output = $output;
+        $this->testFrameworkAdapter = $testFrameworkAdapter;
+    }
+
+    public function getSubscribedEvents(): array
+    {
+        return [
+            InitialTestSuiteStarted::class => [$this, 'onInitialTestSuiteStarted'],
+        ];
+    }
+
+    public function onInitialTestSuiteStarted(InitialTestSuiteStarted $event): void
+    {
+        try {
+            $version = $this->testFrameworkAdapter->getVersion();
+        } catch (\InvalidArgumentException $e) {
+            $version = 'unknown';
+        }
+
+        $this->output->writeln([
+            'Running initial test suite...',
+            '',
+            sprintf(
+                '%s version: %s',
+                $this->testFrameworkAdapter->getName(),
+                $version
+            ),
+        ]);
+    }
+}
diff --git a/src/Process/Listener/CiMutantCreatingConsoleLoggerSubscriber.php b/src/Process/Listener/CiMutantCreatingConsoleLoggerSubscriber.php
new file mode 100644
index 000000000..ca7acb38d
--- /dev/null
+++ b/src/Process/Listener/CiMutantCreatingConsoleLoggerSubscriber.php
@@ -0,0 +1,71 @@
+<?php
+/**
+ * This code is licensed under the BSD 3-Clause License.
+ *
+ * Copyright (c) 2017-2019, Maks Rafalko
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * * Redistributions of source code must retain the above copyright notice, this
+ *   list of conditions and the following disclaimer.
+ *
+ * * Redistributions in binary form must reproduce the above copyright notice,
+ *   this list of conditions and the following disclaimer in the documentation
+ *   and/or other materials provided with the distribution.
+ *
+ * * Neither the name of the copyright holder nor the names of its
+ *   contributors may be used to endorse or promote products derived from
+ *   this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+declare(strict_types=1);
+
+namespace Infection\Process\Listener;
+
+use Infection\EventDispatcher\EventSubscriberInterface;
+use Infection\Events\MutantsCreatingStarted;
+use Symfony\Component\Console\Output\OutputInterface;
+
+/**
+ * @internal
+ */
+final class CiMutantCreatingConsoleLoggerSubscriber implements EventSubscriberInterface
+{
+    /**
+     * @var OutputInterface
+     */
+    private $output;
+
+    public function __construct(OutputInterface $output)
+    {
+        $this->output = $output;
+    }
+
+    public function getSubscribedEvents(): array
+    {
+        return [
+            MutantsCreatingStarted::class => [$this, 'onMutantsCreatingStarted'],
+        ];
+    }
+
+    public function onMutantsCreatingStarted(MutantsCreatingStarted $event): void
+    {
+        $this->output->writeln([
+            '',
+            sprintf('Creating mutated files and processes: %s', $event->getMutantCount()),
+        ]);
+    }
+}
diff --git a/src/Process/Listener/CiMutationGeneratingConsoleLoggerSubscriber.php b/src/Process/Listener/CiMutationGeneratingConsoleLoggerSubscriber.php
new file mode 100644
index 000000000..7ba06c1ac
--- /dev/null
+++ b/src/Process/Listener/CiMutationGeneratingConsoleLoggerSubscriber.php
@@ -0,0 +1,73 @@
+<?php
+/**
+ * This code is licensed under the BSD 3-Clause License.
+ *
+ * Copyright (c) 2017-2019, Maks Rafalko
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * * Redistributions of source code must retain the above copyright notice, this
+ *   list of conditions and the following disclaimer.
+ *
+ * * Redistributions in binary form must reproduce the above copyright notice,
+ *   this list of conditions and the following disclaimer in the documentation
+ *   and/or other materials provided with the distribution.
+ *
+ * * Neither the name of the copyright holder nor the names of its
+ *   contributors may be used to endorse or promote products derived from
+ *   this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+declare(strict_types=1);
+
+namespace Infection\Process\Listener;
+
+use Infection\EventDispatcher\EventSubscriberInterface;
+use Infection\Events\MutationGeneratingStarted;
+use Symfony\Component\Console\Output\OutputInterface;
+
+/**
+ * @internal
+ */
+final class CiMutationGeneratingConsoleLoggerSubscriber implements EventSubscriberInterface
+{
+    /**
+     * @var OutputInterface
+     */
+    private $output;
+
+    public function __construct(OutputInterface $output)
+    {
+        $this->output = $output;
+    }
+
+    public function getSubscribedEvents(): array
+    {
+        return [
+            MutationGeneratingStarted::class => [$this, 'onMutationGeneratingStarted'],
+        ];
+    }
+
+    public function onMutationGeneratingStarted(MutationGeneratingStarted $event): void
+    {
+        $this->output->writeln([
+            '',
+            'Generate mutants...',
+            '',
+            sprintf('Processing source code files: %s', $event->getMutableFilesCount()),
+        ]);
+    }
+}
diff --git a/src/TestFramework/AbstractTestFrameworkAdapter.php b/src/TestFramework/AbstractTestFrameworkAdapter.php
index f15002d56..0efe0a4a5 100644
--- a/src/TestFramework/AbstractTestFrameworkAdapter.php
+++ b/src/TestFramework/AbstractTestFrameworkAdapter.php
@@ -198,7 +198,7 @@ public function getVersion(): string
 
         $process->mustRun();
 
-        $version = null;
+        $version = 'unknown';
 
         try {
             $version = $this->versionParser->parse($process->getOutput());
diff --git a/tests/Console/E2ETest.php b/tests/Console/E2ETest.php
index ad792c591..d2bf4c224 100644
--- a/tests/Console/E2ETest.php
+++ b/tests/Console/E2ETest.php
@@ -67,6 +67,10 @@ final class E2ETest extends TestCase
 
     protected function setUp(): void
     {
+        if (\PHP_SAPI === 'phpdbg') {
+            $this->markTestSkipped('Running this test on PHPDBG causes failures on Travis, see https://github.com/infection/infection/pull/622.');
+        }
+
         // Without overcommit this test fails with `proc_open(): fork failed - Cannot allocate memory`
         if (strpos(PHP_OS, 'Linux') === 0 &&
             is_readable('/proc/sys/vm/overcommit_memory') &&
diff --git a/tests/Process/Builder/SubscriberBuilderTest.php b/tests/Process/Builder/SubscriberBuilderTest.php
index b2955a786..66a34b6be 100644
--- a/tests/Process/Builder/SubscriberBuilderTest.php
+++ b/tests/Process/Builder/SubscriberBuilderTest.php
@@ -57,10 +57,11 @@ final class SubscriberBuilderTest extends TestCase
     public function test_it_registers_the_subscribers_when_debugging(): void
     {
         $input = $this->createMock(InputInterface::class);
-        $input->expects($this->exactly(6))
+        $input->expects($this->exactly(9))
             ->method('getOption')
             ->will($this->returnValueMap(
                 [
+                    ['ci-friendly', false],
                     ['formatter', 'progress'],
                     ['show-mutations', true],
                     ['log-verbosity', 'all'],
@@ -94,10 +95,11 @@ public function test_it_registers_the_subscribers_when_debugging(): void
     public function test_it_registers_the_subscribers_when_not_debugging(): void
     {
         $input = $this->createMock(InputInterface::class);
-        $input->expects($this->exactly(6))
+        $input->expects($this->exactly(9))
             ->method('getOption')
             ->will($this->returnValueMap(
                 [
+                    ['ci-friendly', false],
                     ['formatter', 'progress'],
                     ['show-mutations', true],
                     ['log-verbosity', 'all'],
@@ -131,10 +133,11 @@ public function test_it_registers_the_subscribers_when_not_debugging(): void
     public function test_it_throws_an_exception_when_output_formatter_is_invalid(): void
     {
         $input = $this->createMock(InputInterface::class);
-        $input->expects($this->exactly(2))
+        $input->expects($this->exactly(5))
             ->method('getOption')
             ->will($this->returnValueMap(
                 [
+                    ['ci-friendly', false],
                     ['formatter', 'foo'],
                     ['show-mutations', true],
                 ]
diff --git a/tests/Process/Listener/CiInitialTestsConsoleLoggerSubscriberTest.php b/tests/Process/Listener/CiInitialTestsConsoleLoggerSubscriberTest.php
new file mode 100644
index 000000000..f7fd13d0b
--- /dev/null
+++ b/tests/Process/Listener/CiInitialTestsConsoleLoggerSubscriberTest.php
@@ -0,0 +1,92 @@
+<?php
+/**
+ * This code is licensed under the BSD 3-Clause License.
+ *
+ * Copyright (c) 2017-2019, Maks Rafalko
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * * Redistributions of source code must retain the above copyright notice, this
+ *   list of conditions and the following disclaimer.
+ *
+ * * Redistributions in binary form must reproduce the above copyright notice,
+ *   this list of conditions and the following disclaimer in the documentation
+ *   and/or other materials provided with the distribution.
+ *
+ * * Neither the name of the copyright holder nor the names of its
+ *   contributors may be used to endorse or promote products derived from
+ *   this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+declare(strict_types=1);
+
+namespace Infection\Tests\Process\Listener;
+
+use Infection\EventDispatcher\EventDispatcher;
+use Infection\Events\InitialTestSuiteStarted;
+use Infection\Process\Listener\CiInitialTestsConsoleLoggerSubscriber;
+use Infection\TestFramework\AbstractTestFrameworkAdapter;
+use PHPUnit\Framework\MockObject\MockObject;
+use PHPUnit\Framework\TestCase;
+use Symfony\Component\Console\Output\OutputInterface;
+
+/**
+ * @internal
+ */
+final class CiInitialTestsConsoleLoggerSubscriberTest extends TestCase
+{
+    /**
+     * @var OutputInterface|MockObject
+     */
+    private $output;
+
+    /**
+     * @var AbstractTestFrameworkAdapter|MockObject
+     */
+    private $testFramework;
+
+    protected function setUp(): void
+    {
+        parent::setUp();
+
+        $this->output = $this->createMock(OutputInterface::class);
+        $this->testFramework = $this->createMock(AbstractTestFrameworkAdapter::class);
+    }
+
+    public function test_it_reacts_on_mutants_creating_event(): void
+    {
+        $this->output->expects($this->once())
+            ->method('writeln')
+            ->with([
+                'Running initial test suite...',
+                '',
+                'PHPUnit version: 6.5.4',
+            ]);
+
+        $this->testFramework->expects($this->once())
+            ->method('getVersion')
+            ->willReturn('6.5.4');
+
+        $this->testFramework->expects($this->once())
+            ->method('getName')
+            ->willReturn('PHPUnit');
+
+        $dispatcher = new EventDispatcher();
+        $dispatcher->addSubscriber(new CiInitialTestsConsoleLoggerSubscriber($this->output, $this->testFramework));
+
+        $dispatcher->dispatch(new InitialTestSuiteStarted());
+    }
+}
diff --git a/tests/Process/Listener/CiMutantCreatingConsoleLoggerSubscriberTest.php b/tests/Process/Listener/CiMutantCreatingConsoleLoggerSubscriberTest.php
new file mode 100644
index 000000000..8e26db5f8
--- /dev/null
+++ b/tests/Process/Listener/CiMutantCreatingConsoleLoggerSubscriberTest.php
@@ -0,0 +1,76 @@
+<?php
+/**
+ * This code is licensed under the BSD 3-Clause License.
+ *
+ * Copyright (c) 2017-2019, Maks Rafalko
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * * Redistributions of source code must retain the above copyright notice, this
+ *   list of conditions and the following disclaimer.
+ *
+ * * Redistributions in binary form must reproduce the above copyright notice,
+ *   this list of conditions and the following disclaimer in the documentation
+ *   and/or other materials provided with the distribution.
+ *
+ * * Neither the name of the copyright holder nor the names of its
+ *   contributors may be used to endorse or promote products derived from
+ *   this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+declare(strict_types=1);
+
+namespace Infection\Tests\Process\Listener;
+
+use Infection\EventDispatcher\EventDispatcher;
+use Infection\Events\MutantsCreatingStarted;
+use Infection\Process\Listener\CiMutantCreatingConsoleLoggerSubscriber;
+use PHPUnit\Framework\MockObject\MockObject;
+use PHPUnit\Framework\TestCase;
+use Symfony\Component\Console\Output\OutputInterface;
+
+/**
+ * @internal
+ */
+final class CiMutantCreatingConsoleLoggerSubscriberTest extends TestCase
+{
+    /**
+     * @var OutputInterface|MockObject
+     */
+    private $output;
+
+    protected function setUp(): void
+    {
+        parent::setUp();
+
+        $this->output = $this->createMock(OutputInterface::class);
+    }
+
+    public function test_it_reacts_on_mutants_creating_event(): void
+    {
+        $this->output->expects($this->once())
+            ->method('writeln')
+            ->with([
+                '',
+                'Creating mutated files and processes: 123',
+            ]);
+
+        $dispatcher = new EventDispatcher();
+        $dispatcher->addSubscriber(new CiMutantCreatingConsoleLoggerSubscriber($this->output));
+
+        $dispatcher->dispatch(new MutantsCreatingStarted(123));
+    }
+}
diff --git a/tests/Process/Listener/CiMutationGeneratingConsoleLoggerSubscriberTest.php b/tests/Process/Listener/CiMutationGeneratingConsoleLoggerSubscriberTest.php
new file mode 100644
index 000000000..d1fd2b9a2
--- /dev/null
+++ b/tests/Process/Listener/CiMutationGeneratingConsoleLoggerSubscriberTest.php
@@ -0,0 +1,78 @@
+<?php
+/**
+ * This code is licensed under the BSD 3-Clause License.
+ *
+ * Copyright (c) 2017-2019, Maks Rafalko
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * * Redistributions of source code must retain the above copyright notice, this
+ *   list of conditions and the following disclaimer.
+ *
+ * * Redistributions in binary form must reproduce the above copyright notice,
+ *   this list of conditions and the following disclaimer in the documentation
+ *   and/or other materials provided with the distribution.
+ *
+ * * Neither the name of the copyright holder nor the names of its
+ *   contributors may be used to endorse or promote products derived from
+ *   this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+declare(strict_types=1);
+
+namespace Infection\Tests\Process\Listener;
+
+use Infection\EventDispatcher\EventDispatcher;
+use Infection\Events\MutationGeneratingStarted;
+use Infection\Process\Listener\CiMutationGeneratingConsoleLoggerSubscriber;
+use PHPUnit\Framework\MockObject\MockObject;
+use PHPUnit\Framework\TestCase;
+use Symfony\Component\Console\Output\OutputInterface;
+
+/**
+ * @internal
+ */
+final class CiMutationGeneratingConsoleLoggerSubscriberTest extends TestCase
+{
+    /**
+     * @var OutputInterface|MockObject
+     */
+    private $output;
+
+    protected function setUp(): void
+    {
+        parent::setUp();
+
+        $this->output = $this->createMock(OutputInterface::class);
+    }
+
+    public function test_it_reacts_on_mutation_generating_started_event(): void
+    {
+        $this->output->expects($this->once())
+            ->method('writeln')
+            ->with([
+                '',
+                'Generate mutants...',
+                '',
+                'Processing source code files: 123',
+            ]);
+
+        $dispatcher = new EventDispatcher();
+        $dispatcher->addSubscriber(new CiMutationGeneratingConsoleLoggerSubscriber($this->output));
+
+        $dispatcher->dispatch(new MutationGeneratingStarted(123));
+    }
+}