Fix Tree command. (#69)

The code to invoke the `git ls-tree` command was wrong, and resulted in
the nonexisting command `git tree ls-tree` being invoked instead. This
patch fixes the issue so the tree command can be used again.

src/Command/Tree.php

@@ -47,7 +47,7 @@ public function __invoke(string $branch = 'master', string $path = ''): array
     {
         $objects = [];
         $builder = $this->getCommandBuilder();
-        $builder->add('ls-tree')->add($branch . ':' . $path);
+        $builder->add($branch . ':' . $path);
 
         $output = $this->run($builder);
 
@@ -73,4 +73,9 @@ public function __invoke(string $branch = 'master', string $path = ''): array
 
         return $objects;
     }
+
+    public function getCommandName(): string
+    {
+        return 'ls-tree';
+    }
 }

test/Command/TreeTest.php

@@ -0,0 +1,54 @@
+<?php declare(strict_types=1);
+/**
+ * phpGit - A Git wrapper for PHP
+ *
+ * @author   https://github.com/inhere
+ * @link     https://github.com/phppkg/phpgit
+ * @license  MIT
+ */
+
+namespace PhpGitTest\Command;
+
+use PhpGit\Exception\GitException;
+use PhpGit\Git;
+use PhpGitTest\BasePhpGitTestCase;
+use Symfony\Component\Filesystem\Filesystem;
+
+
+class TreeTest extends BasePhpGitTestCase
+{
+    public function testListBranch(): void
+    {
+        $filesystem = new Filesystem();
+
+        $git = new Git();
+        $git->init($this->directory);
+        $git->setRepository($this->directory);
+        $filesystem->dumpFile($this->directory . '/README.md', 'hello');
+        $git->add('.');
+        $git->commit('Initial commit');
+
+        $result = $git->tree('master');
+
+        $this->assertIsArray($result);
+        $this->assertCount(1, $result);
+
+        $inner = array_shift($result);
+
+        $this->assertIsArray($inner);
+        $this->assertArrayHasKey('sort', $inner);
+        $this->assertEquals('2:README.md', $inner['sort']);
+
+        $this->assertArrayHasKey('type', $inner);
+        $this->assertEquals('blob', $inner['type']);
+
+        $this->assertArrayHasKey('mode', $inner);
+        $this->assertEquals(100644, $inner['mode']);
+
+        $this->assertArrayHasKey('hash', $inner);
+        $this->assertEquals('b6fc4c620b67d95f953a5c1c1230aaab5db5a1b0', $inner['hash']);
+
+        $this->assertArrayHasKey('file', $inner);
+        $this->assertEquals('README.md', $inner['file']);
+    }
+}