Fix #27523: throw informative errors in setup:db:generate-patch

app/code/Magento/Developer/Console/Command/GeneratePatchCommand.php

@@ -133,6 +133,9 @@ protected function execute(InputInterface $input, OutputInterface $output): int
         }
         $type = $input->getOption(self::INPUT_KEY_PATCH_TYPE);
         $modulePath = $this->componentRegistrar->getPath(ComponentRegistrar::MODULE, $moduleName);
+        if (null === $modulePath) {
+            throw new \InvalidArgumentException(sprintf('Cannot find a registered module with name "%s"', $moduleName));
+        }
         $preparedModuleName = str_replace('_', '\\', $moduleName);
         $preparedType = ucfirst($type);
         $patchInterface = sprintf('%sPatchInterface', $preparedType);

app/code/Magento/Developer/Test/Unit/Console/Command/GeneratePatchCommandTest.php

@@ -0,0 +1,118 @@
+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+
+namespace Magento\Developer\Test\Unit\Console\Command;
+
+use Magento\Developer\Console\Command\GeneratePatchCommand;
+use Magento\Framework\Component\ComponentRegistrar;
+use Magento\Framework\Filesystem\Directory\ReadFactory;
+use Magento\Framework\Filesystem\Directory\WriteFactory;
+use Magento\Framework\Filesystem\DirectoryList;
+use Symfony\Component\Console\Tester\CommandTester;
+
+class GeneratePatchCommandTest extends \PHPUnit\Framework\TestCase
+{
+    /**
+     * @var ComponentRegistrar
+     */
+    private $componentRegistrar;
+
+    /**
+     * @var DirectoryList
+     */
+    private $directoryList;
+
+    /**
+     * @var ReadFactory
+     */
+    private $readFactory;
+
+    /**
+     * @var WriteFactory
+     */
+    private $writeFactory;
+
+    /**
+     * @var GeneratePatchCommand
+     */
+    private $command;
+
+    protected function setUp()
+    {
+        $this->componentRegistrar = $this->createMock(ComponentRegistrar::class);
+        $this->directoryList = $this->createMock(DirectoryList::class);
+        $this->readFactory = $this->createMock(ReadFactory::class);
+        $this->writeFactory = $this->createMock(WriteFactory::class);
+
+        $this->command = new GeneratePatchCommand(
+            $this->componentRegistrar,
+            $this->directoryList,
+            $this->readFactory,
+            $this->writeFactory
+        );
+    }
+
+    public function testExecute()
+    {
+        $this->componentRegistrar->expects($this->once())
+            ->method('getPath')
+            ->with('module', 'Vendor_Module')
+            ->willReturn('/long/path/to/Vendor/Module');
+
+        $read = $this->createMock(\Magento\Framework\Filesystem\Directory\Read::class);
+        $read->expects($this->at(0))
+            ->method('readFile')
+            ->with('patch_template.php.dist')
+            ->willReturn('something');
+        $this->readFactory->method('create')->willReturn($read);
+
+        $write = $this->createMock(\Magento\Framework\Filesystem\Directory\Write::class);
+        $write->expects($this->once())->method('writeFile');
+        $this->writeFactory->method('create')->willReturn($write);
+
+        $this->directoryList->expects($this->once())->method('getRoot')->willReturn('/some/path');
+
+        $commandTester = new CommandTester($this->command);
+        $commandTester->execute(
+            [
+                GeneratePatchCommand::MODULE_NAME => 'Vendor_Module',
+                GeneratePatchCommand::INPUT_KEY_PATCH_NAME => 'SomePatch'
+            ]
+        );
+        $this->assertContains('successfully generated', $commandTester->getDisplay());
+    }
+
+    /**
+     * @expectedException \RuntimeException
+     * @expectedExceptionMessage Not enough arguments
+     */
+    public function testWrongParameter()
+    {
+        $commandTester = new CommandTester($this->command);
+        $commandTester->execute([]);
+    }
+
+    /**
+     * @expectedException \InvalidArgumentException
+     * @expectedExceptionMessage Cannot find a registered module with name "Fake_Module"
+     */
+    public function testBadModule()
+    {
+        $this->componentRegistrar->expects($this->once())
+            ->method('getPath')
+            ->with('module', 'Fake_Module')
+            ->willReturn(null);
+
+        $commandTester = new CommandTester($this->command);
+        $commandTester->execute(
+            [
+                GeneratePatchCommand::MODULE_NAME => 'Fake_Module',
+                GeneratePatchCommand::INPUT_KEY_PATCH_NAME => 'SomePatch'
+            ]
+        );
+        $this->assertContains('successfully generated', $commandTester->getDisplay());
+    }
+}