diff --git a/src/Psalm/PluginManager/PluginList.php b/src/Psalm/PluginManager/PluginList.php
index f518a3d0b68..c5bffd14049 100644
--- a/src/Psalm/PluginManager/PluginList.php
+++ b/src/Psalm/PluginManager/PluginList.php
@@ -31,7 +31,6 @@ public function getEnabled(): array
             $this->enabled_plugins = [];
             foreach ($this->config_file->getConfig()->getPluginClasses() as $plugin_entry) {
                 $plugin_class = $plugin_entry['class'];
-                $plugin_config = $plugin_entry['config'];
                 $this->enabled_plugins[$plugin_class] = $this->findPluginPackage($plugin_class);
             }
         }
diff --git a/tests/PluginManager.php b/tests/PluginManager.php
new file mode 100644
index 00000000000..41ebdc48a4a
--- /dev/null
+++ b/tests/PluginManager.php
@@ -0,0 +1,179 @@
+<?php
+namespace Psalm\Tests;
+
+use Prophecy\Prophecy\ObjectProphecy;
+use Psalm\Config;
+use Psalm\PluginManager\ComposerLock;
+use Psalm\PluginManager\ConfigFile;
+use Psalm\PluginManager\PluginList;
+
+class PluginManagerTest extends TestCase
+{
+    /** @var ObjectProphecy */
+    private $config_file;
+    /** @var ObjectProphecy */
+    private $config;
+    /** @var ObjectProphecy */
+    private $composer_lock;
+
+    public function setUp()
+    {
+        $this->config = $this->prophesize(Config::class);
+        /** @psalm-suppress TooManyArguments willReturn is old-school variadic, see vimeo/psalm#605 */
+        $this->config->getPluginClasses()->willReturn([]);
+
+        $this->config_file = $this->prophesize(ConfigFile::class);
+        /** @psalm-suppress TooManyArguments willReturn is old-school variadic, see vimeo/psalm#605 */
+        $this->config_file->getConfig()->willReturn($this->config->reveal());
+
+        $this->composer_lock = $this->prophesize(ComposerLock::class);
+        /** @psalm-suppress TooManyArguments willReturn is old-school variadic, see vimeo/psalm#605 */
+        $this->composer_lock->getPlugins()->willReturn([]);
+    }
+
+    /**
+     * @return void
+     * @test
+     */
+    public function pluginsPresentInConfigAreEnabled()
+    {
+        /** @psalm-suppress TooManyArguments willReturn is old-school variadic, see vimeo/psalm#605 */
+        $this->config->getPluginClasses()->willReturn([
+            ['class' => 'a\b\c', 'config' => null],
+            ['class' => 'c\d\e', 'config' => null],
+        ]);
+
+        $plugin_list = new PluginList($this->config_file->reveal(), $this->composer_lock->reveal());
+
+        $this->assertEquals([
+            'a\b\c' => null,
+            'c\d\e' => null,
+        ], $plugin_list->getEnabled());
+    }
+
+    /**
+     * @return void
+     * @test
+     */
+    public function pluginsPresentInPackageLockOnlyAreAvailable()
+    {
+        /** @psalm-suppress TooManyArguments willReturn is old-school variadic, see vimeo/psalm#605 */
+        $this->config->getPluginClasses()->willReturn([
+            ['class' => 'a\b\c', 'config' => null],
+        ]);
+
+        /** @psalm-suppress TooManyArguments willReturn is old-school variadic, see vimeo/psalm#605 */
+        $this->composer_lock->getPlugins()->willReturn([
+            'vendor/package' => 'a\b\c',
+            'another-vendor/another-package' => 'c\d\e',
+        ]);
+
+        $plugin_list = new PluginList($this->config_file->reveal(), $this->composer_lock->reveal());
+
+        $this->assertEquals([
+            'c\d\e' => 'another-vendor/another-package',
+        ], $plugin_list->getAvailable());
+    }
+
+    /**
+     * @return void
+     * @test
+     */
+    public function pluginsPresentInPackageLockAndConfigHavePluginPackageName()
+    {
+        /** @psalm-suppress TooManyArguments willReturn is old-school variadic, see vimeo/psalm#605 */
+        $this->config->getPluginClasses()->willReturn([
+            ['class' => 'a\b\c', 'config' => null],
+        ]);
+
+        /** @psalm-suppress TooManyArguments willReturn is old-school variadic, see vimeo/psalm#605 */
+        $this->composer_lock->getPlugins()->willReturn([
+            'vendor/package' => 'a\b\c',
+        ]);
+
+        $plugin_list = new PluginList($this->config_file->reveal(), $this->composer_lock->reveal());
+
+        $this->assertEquals([
+            'a\b\c' => 'vendor/package',
+        ], $plugin_list->getEnabled());
+    }
+
+    /**
+     * @return void
+     * @test
+     */
+    public function canFindPluginClassByClassName()
+    {
+        $plugin_list = new PluginList($this->config_file->reveal(), $this->composer_lock->reveal());
+        $this->assertEquals('a\b\c', $plugin_list->resolvePluginClass('a\b\c'));
+    }
+
+    /**
+     * @return void
+     * @test
+     */
+    public function canFindPluginClassByPackageName()
+    {
+        /** @psalm-suppress TooManyArguments willReturn is old-school variadic, see vimeo/psalm#605 */
+        $this->composer_lock->getPlugins()->willReturn([
+            'vendor/package' => 'a\b\c',
+        ]);
+
+        $plugin_list = new PluginList($this->config_file->reveal(), $this->composer_lock->reveal());
+        $this->assertEquals('a\b\c', $plugin_list->resolvePluginClass('vendor/package'));
+    }
+
+    /**
+     * @return void
+     * @test
+     */
+    public function enabledPackageIsEnabled()
+    {
+        /** @psalm-suppress TooManyArguments willReturn is old-school variadic, see vimeo/psalm#605 */
+        $this->config->getPluginClasses()->willReturn([
+            ['class' => 'a\b\c', 'config' => null],
+        ]);
+
+        $plugin_list = new PluginList($this->config_file->reveal(), $this->composer_lock->reveal());
+
+        $this->assertTrue($plugin_list->isEnabled('a\b\c'));
+    }
+
+    /**
+     * @return void
+     * @test
+     */
+    public function errorsOutWhenTryingToResolveUnknownPlugin()
+    {
+        $plugin_list = new PluginList($this->config_file->reveal(), $this->composer_lock->reveal());
+        $this->expectException(\InvalidArgumentException::class);
+        $this->expectExceptionMessageRegExp('/unknown plugin/i');
+        $plugin_list->resolvePluginClass('vendor/package');
+    }
+
+    /**
+     * @return void
+     * @test
+     */
+    public function pluginsAreEnabledInConfigFile()
+    {
+        $plugin_list = new PluginList($this->config_file->reveal(), $this->composer_lock->reveal());
+
+        $this->config_file->addPlugin('a\b\c')->shouldBeCalled();
+
+        $plugin_list->enable('a\b\c');
+    }
+
+    /**
+     * @return void
+     * @test
+     */
+    public function pluginsAreDisabledInConfigFile()
+    {
+        $plugin_list = new PluginList($this->config_file->reveal(), $this->composer_lock->reveal());
+
+        $this->config_file->removePlugin('a\b\c')->shouldBeCalled();
+
+        $plugin_list->disable('a\b\c');
+    }
+}