added test for gendiff

Author: Alexsey-VR

src/Gendiff.php

@@ -2,7 +2,7 @@
 
 namespace Differ;
 
-function runGendiff(): void
+function runGendiff(CommandFactoryInterface $commandFactory = null): void
 {
     $docopt = <<<'DOCOPT'
     gendiff -h
@@ -21,7 +21,10 @@ function runGendiff(): void
 
     DOCOPT;
 
-    $commandFactory = new CommandFactory($docopt);
+    if (is_null($commandFactory)) {
+        $commandFactory = new CommandFactory($docopt);
+    }
+    
     $fileReader = new FileReader();
 
     $consoleApp = new ConsoleApp($commandFactory, $fileReader);

tests/DifferTest.php

@@ -0,0 +1,58 @@
+<?php
+
+namespace Differ;
+
+//require_once __DIR__ . '/../vendor/autoload.php';
+
+use PHPUnit\Framework\TestCase;
+use PHPUnit\Framework\Attributes\CoversFunction;
+use PHPUnit\Framework\Attributes\CoversNothing;
+use function Differ\runGendiff;
+
+#[CoversNothing]
+class GendiffTest extends TestCase
+{
+    public function testRunGendiff()
+    {
+        $outputString = "{\n" .
+        "    hexlet.io\n" .
+        "  - 50\n" .
+        "  + 20\n" .
+        "  - 123.234.53.22\n" .
+        "  - \n" .
+        "}\n";
+
+        $commandLineParserStubToGetContent = $this->createConfiguredStub(
+            CommandLineParser::class,
+            [
+                'getFileNames' => [
+                    'FILE1' => __DIR__ . "/../file1.json",
+                    'FILE2' => __DIR__ . "/../file2.json"
+                ]
+            ]
+        );
+        $cmdLineParserStub = $this->createConfiguredStub(
+            CommandLineParser::class,
+            [
+                'execute' => $commandLineParserStubToGetContent
+            ]
+        );
+
+        $filesDiffCommand = new FilesDiffCommand();
+        $displayCommand = new DisplayCommand();
+
+        $commandFactoryMock = $this->createMock(CommandFactory::class);
+        $commandFactoryMock->expects($this->exactly(3))
+                           ->method('getCommand')
+                           ->willReturnMap([
+                                ['parse', $cmdLineParserStub],
+                                ['difference', $filesDiffCommand],
+                                ['show', $displayCommand]
+                           ]);
+
+        $this->expectOutputString(
+            $outputString);        
+
+        runGendiff($commandFactoryMock);
+    }
+}