Include plugin bootstrap on the first time.

If a plugin is loaded through the static method it should be immediately
bootstrapped, as that is how Plugin::load() has worked for a long time.
Because many 3.x plugins rely on their bootstrap file only being executed
once per process, we need to disable the bootstrap hook so that
`app->pluginBootstrap()` doesn't re-trigger the bootstrap steps.

Refs #11816

src/Core/Plugin.php

@@ -174,10 +174,7 @@ class Plugin
             );
         }
 
-        // Defer the bootstrap process if an Application class exists.
-        // Immediate plugin bootstrapping is deprecated and will be removed in 4.x
-        $appClass = Configure::read('App.namespace') . '\\' . 'Application';
-        if ($config['bootstrap'] === true && !class_exists($appClass)) {
+        if ($config['bootstrap'] === true) {
             static::bootstrap($plugin);
         }
     }
@@ -316,6 +313,9 @@ class Plugin
         if (!$plugin->isEnabled('bootstrap')) {
             return false;
         }
+        // Disable bootstrapping for this plugin as it will have
+        // been bootstrapped.
+        $plugin->disable('bootstrap');
 
         return static::_includeFile(
             $plugin->getConfigPath() . 'bootstrap.php',

tests/TestCase/Core/PluginTest.php

@@ -39,7 +39,7 @@ class PluginTest extends TestCase
      *
      * @return void
      */
-    public function testLoadSingle()
+    public function testLoad()
     {
         Plugin::unload();
         Plugin::load('TestPlugin');
@@ -74,7 +74,7 @@ class PluginTest extends TestCase
      *
      * @return void
      */
-    public function testLoadSingleWithAutoload()
+    public function testLoadWithAutoload()
     {
         $this->assertFalse(class_exists('Company\TestPluginFive\Utility\Hello'));
         Plugin::load('Company/TestPluginFive', [
@@ -91,7 +91,7 @@ class PluginTest extends TestCase
      *
      * @return void
      */
-    public function testLoadSingleWithAutoloadAndBootstrap()
+    public function testLoadWithAutoloadAndBootstrap()
     {
         Plugin::load(
             'Company/TestPluginFive',
@@ -111,10 +111,9 @@ class PluginTest extends TestCase
     /**
      * Tests loading a plugin and its bootstrap file
      *
-     * @deprecated Immediate plugin bootstrap should be removed in 4.x
      * @return void
      */
-    public function testLoadSingleWithBootstrap()
+    public function testLoadWithBootstrap()
     {
         Plugin::load('TestPlugin', ['bootstrap' => true]);
         $this->assertTrue(Plugin::loaded('TestPlugin'));
@@ -126,17 +125,18 @@ class PluginTest extends TestCase
     }
 
     /**
-     * Tests loading a plugin defers bootstrap when an application exists
+     * Tests loading a plugin and its bootstrap file
      *
      * @return void
      */
-    public function testLoadSingleDeferBootstrap()
+    public function testLoadWithBootstrapDisableBootstrapHook()
     {
-        static::setAppNamespace('TestApp');
-
         Plugin::load('TestPlugin', ['bootstrap' => true]);
         $this->assertTrue(Plugin::loaded('TestPlugin'));
-        $this->assertNull(Configure::read('PluginTest.test_plugin.bootstrap'), 'Normally this value would be loaded');
+        $this->assertEquals('loaded plugin bootstrap', Configure::read('PluginTest.test_plugin.bootstrap'));
+
+        $plugin = Plugin::getCollection()->get('TestPlugin');
+        $this->assertFalse($plugin->isEnabled('bootstrap'), 'Should be disabled as hook has been run.');
     }
 
     /**

tests/TestCase/Http/BaseApplicationTest.php

@@ -159,4 +159,27 @@ class BaseApplicationTest extends TestCase
         $this->assertNull($app->pluginBootstrap());
         $this->assertTrue(Configure::check('PluginTest.test_plugin.bootstrap'));
     }
+
+    /**
+     * Ensure that plugins loaded via Plugin::load()
+     * don't have their bootstrapping run twice.
+     *
+     * @return void
+     */
+    public function testPluginBootstrapInteractWithPluginLoad()
+    {
+        Plugin::load('TestPlugin', ['bootstrap' => true]);
+        $app = $this->getMockForAbstractClass(
+            BaseApplication::class,
+            [$this->path]
+        );
+        $this->assertTrue(Configure::check('PluginTest.test_plugin.bootstrap'));
+        Configure::delete('PluginTest.test_plugin.bootstrap');
+
+        $this->assertNull($app->pluginBootstrap());
+        $this->assertFalse(
+            Configure::check('PluginTest.test_plugin.bootstrap'),
+            'Key should not be set, as plugin has already had bootstrap run'
+        );
+    }
 }