diff --git a/module/CLI/test/Install/Plugin/ApplicationConfigCustomizerPluginTest.php b/module/CLI/test/Install/Plugin/ApplicationConfigCustomizerPluginTest.php
new file mode 100644
index 00000000..cd4cef42
--- /dev/null
+++ b/module/CLI/test/Install/Plugin/ApplicationConfigCustomizerPluginTest.php
@@ -0,0 +1,96 @@
+<?php
+declare(strict_types=1);
+
+namespace ShlinkioTest\Shlink\CLI\Install\Plugin;
+
+use PHPUnit\Framework\TestCase;
+use Prophecy\Argument;
+use Prophecy\Prophecy\MethodProphecy;
+use Prophecy\Prophecy\ObjectProphecy;
+use Shlinkio\Shlink\CLI\Install\Plugin\ApplicationConfigCustomizerPlugin;
+use Shlinkio\Shlink\CLI\Model\CustomizableAppConfig;
+use Symfony\Component\Console\Helper\QuestionHelper;
+use Symfony\Component\Console\Input\ArrayInput;
+use Symfony\Component\Console\Output\NullOutput;
+use Symfony\Component\Console\Question\ConfirmationQuestion;
+
+class ApplicationConfigCustomizerPluginTest extends TestCase
+{
+    /**
+     * @var ApplicationConfigCustomizerPlugin
+     */
+    private $plugin;
+    /**
+     * @var ObjectProphecy
+     */
+    private $questionHelper;
+
+    public function setUp()
+    {
+        $this->questionHelper = $this->prophesize(QuestionHelper::class);
+        $this->plugin = new ApplicationConfigCustomizerPlugin($this->questionHelper->reveal());
+    }
+
+    /**
+     * @test
+     */
+    public function configIsRequestedToTheUser()
+    {
+        /** @var MethodProphecy $askSecret */
+        $askSecret = $this->questionHelper->ask(Argument::cetera())->willReturn('the_secret');
+        $config = new CustomizableAppConfig();
+
+        $this->plugin->process(new ArrayInput([]), new NullOutput(), $config);
+
+        $this->assertTrue($config->hasApp());
+        $this->assertEquals([
+            'SECRET' => 'the_secret',
+        ], $config->getApp());
+        $askSecret->shouldHaveBeenCalledTimes(1);
+    }
+
+    /**
+     * @test
+     */
+    public function overwriteIsRequestedIfValueIsAlreadySet()
+    {
+        /** @var MethodProphecy $ask */
+        $ask = $this->questionHelper->ask(Argument::cetera())->will(function (array $args) {
+            $last = array_pop($args);
+            return $last instanceof ConfirmationQuestion ? false : 'the_new_secret';
+        });
+        $config = new CustomizableAppConfig();
+        $config->setApp([
+            'SECRET' => 'foo',
+        ]);
+
+        $this->plugin->process(new ArrayInput([]), new NullOutput(), $config);
+
+        $this->assertEquals([
+            'SECRET' => 'the_new_secret',
+        ], $config->getApp());
+        $ask->shouldHaveBeenCalledTimes(2);
+    }
+
+    /**
+     * @test
+     */
+    public function existingValueIsKeptIfRequested()
+    {
+        /** @var MethodProphecy $ask */
+        $ask = $this->questionHelper->ask(Argument::cetera())->willReturn(true);
+
+
+        $config = new CustomizableAppConfig();
+        $config->setApp([
+            'SECRET' => 'foo',
+        ]);
+
+        $this->plugin->process(new ArrayInput([]), new NullOutput(), $config);
+
+        $this->assertEquals([
+            'SECRET' => 'foo',
+        ], $config->getApp());
+        $ask->shouldHaveBeenCalledTimes(1);
+    }
+}