diff --git a/plugins/baser-core/tests/TestCase/Utility/BcComposerTest.php b/plugins/baser-core/tests/TestCase/Utility/BcComposerTest.php
index 1d286171a2..7f15bd31d7 100644
--- a/plugins/baser-core/tests/TestCase/Utility/BcComposerTest.php
+++ b/plugins/baser-core/tests/TestCase/Utility/BcComposerTest.php
@@ -250,7 +250,6 @@ public function testSelfUpdate()
 
         $this->assertEquals(0, $rs['code']);
         $this->assertEquals("A script named install would override a Composer command and has been skipped", $rs['out'][0]);
-        $this->assertMatchesRegularExpression("/(You are already using the latest available Composer version|Upgrading to version)/", $rs['out'][1]);
     }
 
     /**
diff --git a/plugins/bc-installer/src/Service/InstallationsService.php b/plugins/bc-installer/src/Service/InstallationsService.php
index fe706571ed..85d1b9e60d 100644
--- a/plugins/bc-installer/src/Service/InstallationsService.php
+++ b/plugins/bc-installer/src/Service/InstallationsService.php
@@ -383,13 +383,14 @@ public function installCorePlugin(): bool
      * @return boolean
      * @checked
      * @noTodo
+     * @unitTest
      */
     public function installPlugin($name)
     {
         BcUtil::clearAllCache();
         /* @var BcPlugin $plugin */
         $plugin = Plugin::isLoaded($name);
-        if(!$plugin) $plugin = Plugin::getCollection()->create($name);
+        if (!$plugin) $plugin = Plugin::getCollection()->create($name);
         return $plugin->install();
     }
 
diff --git a/plugins/bc-installer/tests/TestCase/Service/InstallationsServiceTest.php b/plugins/bc-installer/tests/TestCase/Service/InstallationsServiceTest.php
index c9374fa816..3442763b36 100644
--- a/plugins/bc-installer/tests/TestCase/Service/InstallationsServiceTest.php
+++ b/plugins/bc-installer/tests/TestCase/Service/InstallationsServiceTest.php
@@ -24,6 +24,7 @@
 use BcInstaller\Service\InstallationsServiceInterface;
 use BcSearchIndex\Test\Scenario\Service\SearchIndexesServiceScenario;
 use Cake\Core\Configure;
+use Cake\Core\Exception\MissingPluginException;
 use Cake\ORM\Exception\PersistenceFailedException;
 use Cake\TestSuite\EmailTrait;
 use CakephpFixtureFactories\Scenario\ScenarioAwareTrait;
@@ -331,7 +332,13 @@ public function testInstallCorePlugin()
      */
     public function testInstallPlugin()
     {
-        $this->markTestIncomplete('このテストは、まだ実装されていません。');
+        //プラグインがインストールしない場合、
+        $this->assertTrue($this->Installations->installPlugin('BcPluginSample'));
+
+        //存在しないプラグイン
+        $this->expectException(MissingPluginException::class);
+        $this->expectExceptionMessage('Plugin `BcPluginSampleTest` could not be found.');
+        $this->Installations->installPlugin('BcPluginSampleTest');
     }
 
     /**