Let app plugins override vendor plugins again

README.md

@@ -26,6 +26,13 @@ only need to specify the `type` in their composer config:
 "type": "cakephp-plugin"
 ```
 
+## App Plugins
+
+Plugins in your application's `plugins/` directory are added to the generated
+`cakephp-plugins.php` as well. If a plugin exists both there and in `vendor/`,
+the one in `plugins/` is used. This lets you work on a local copy of a plugin
+that is also installed through composer.
+
 ## Multiple Plugin Paths
 
 If your application uses multiple plugin paths. In addition to configuring your

src/Plugin.php

@@ -140,19 +140,24 @@ public function findPlugins(
                 continue;
             }
 
-            $ns = $this->getPrimaryNamespace($package);
+            // Same key format as app plugins, so `Vendor/Plugin` in plugins/ can replace it.
+            $ns = str_replace('\\', '/', $this->getPrimaryNamespace($package));
             $path = $vendorDir . DIRECTORY_SEPARATOR . $package->getPrettyName();
             $plugins[$ns] = $path;
         }
 
+        $appPlugins = [];
         foreach ($pluginDirs as $path) {
             $path = $this->getFullPath($path, $vendorDir);
             if (!is_dir($path)) {
                 continue;
             }
-            $plugins += $this->findAppPlugins($path, true);
+            $appPlugins += $this->findAppPlugins($path, true);
         }
 
+        // App plugins take priority over vendor plugins of the same name.
+        $plugins = $appPlugins + $plugins;
+
         ksort($plugins);
 
         return $plugins;

tests/TestCase/PluginTest.php

@@ -354,6 +354,45 @@ public function testFindPlugins()
         $this->assertSame($expected, $return, 'Composer and application plugins should be listed');
     }
 
+    public function testFindPluginsAppPluginOverridesVendorPlugin()
+    {
+        $package = new Package('cakephp/fee', '1.0', '1.0');
+        $package->setType('cakephp-plugin');
+        $package->setAutoload([
+            'psr-4' => [
+                'Fee' => 'src/',
+            ],
+        ]);
+
+        $return = $this->plugin->findPlugins(
+            [$package],
+            [$this->path . '/plugins'],
+            $this->path . '/vendor',
+        );
+
+        $this->assertSame($this->path . '/plugins/Fee', $return['Fee']);
+    }
+
+    public function testFindPluginsNamespacedAppPluginOverridesVendorPlugin()
+    {
+        $package = new Package('your-vendor/your-plugin', '1.0', '1.0');
+        $package->setType('cakephp-plugin');
+        $package->setAutoload([
+            'psr-4' => [
+                'YourVendor\\YourPlugin\\' => 'src/',
+            ],
+        ]);
+
+        $return = $this->plugin->findPlugins(
+            [$package],
+            [$this->path . '/plugins'],
+            $this->path . '/vendor',
+        );
+
+        $this->assertSame($this->path . '/plugins/YourVendor/YourPlugin', $return['YourVendor/YourPlugin']);
+        $this->assertArrayNotHasKey('YourVendor\\YourPlugin', $return);
+    }
+
     public function testWriteConfigFile()
     {
         $plugins = [