diff --git a/src/Users/User.php b/src/Users/User.php
index bc6b9af1..b8dd6772 100644
--- a/src/Users/User.php
+++ b/src/Users/User.php
@@ -99,9 +99,7 @@ class User extends Model
 
     public function validatePassword(string $password): bool
     {
-        $verification = password_verify($password, $this->password);
-
-        if ($verification !== true) {
+        if (password_verify($password, $this->password) !== true) {
             return false;
         }
 
diff --git a/tests/FileSystemTest.php b/tests/FileSystemTest.php
index 0595a022..6c0d2b4e 100644
--- a/tests/FileSystemTest.php
+++ b/tests/FileSystemTest.php
@@ -6,10 +6,15 @@ use Misuzu\IO\Directory;
 use Misuzu\IO\File;
 use Misuzu\IO\FileStream;
 
-define('WORKING_DIR', sys_get_temp_dir() . '/MisuzuFileSystemTest' . time());
-
 class FileSystemTest extends TestCase
 {
+    protected $workingDirectory;
+
+    protected function setUp()
+    {
+        $this->workingDirectory = sys_get_temp_dir() . '/MisuzuFileSystemTest' . time();
+    }
+
     public function testSlashFix()
     {
         $right_slash = DIRECTORY_SEPARATOR;
@@ -24,25 +29,25 @@ class FileSystemTest extends TestCase
     public function testExists()
     {
         $this->assertTrue(Directory::exists(sys_get_temp_dir()));
-        $this->assertFalse(Directory::exists(WORKING_DIR));
+        $this->assertFalse(Directory::exists($this->workingDirectory));
     }
 
     public function testCreateDir()
     {
-        $directory = Directory::create(WORKING_DIR);
+        $directory = Directory::create($this->workingDirectory);
         $this->assertInstanceOf(Directory::class, $directory);
     }
 
     public function testCreateFile()
     {
-        $file = File::open(WORKING_DIR . '/file');
+        $file = File::open($this->workingDirectory . '/file');
         $this->assertInstanceOf(FileStream::class, $file);
         $file->close();
     }
 
     public function testWriteFile()
     {
-        $file = new FileStream(WORKING_DIR . '/file', FileStream::MODE_TRUNCATE);
+        $file = new FileStream($this->workingDirectory . '/file', FileStream::MODE_TRUNCATE);
         $this->assertInstanceOf(FileStream::class, $file);
 
         $file->write('mis');
@@ -54,7 +59,7 @@ class FileSystemTest extends TestCase
 
     public function testAppendFile()
     {
-        $file = new FileStream(WORKING_DIR . '/file', FileStream::MODE_APPEND);
+        $file = new FileStream($this->workingDirectory . '/file', FileStream::MODE_APPEND);
         $this->assertInstanceOf(FileStream::class, $file);
 
         $file->write(' test');
@@ -65,7 +70,7 @@ class FileSystemTest extends TestCase
 
     public function testPosition()
     {
-        $file = new FileStream(WORKING_DIR . '/file', FileStream::MODE_READ);
+        $file = new FileStream($this->workingDirectory . '/file', FileStream::MODE_READ);
         $this->assertInstanceOf(FileStream::class, $file);
 
         $file->seek(0, FileStream::ORIGIN_BEGIN);
@@ -85,7 +90,7 @@ class FileSystemTest extends TestCase
 
     public function testRead()
     {
-        $file = new FileStream(WORKING_DIR . '/file', FileStream::MODE_READ);
+        $file = new FileStream($this->workingDirectory . '/file', FileStream::MODE_READ);
         $this->assertInstanceOf(FileStream::class, $file);
 
         $this->assertEquals('misuzu test', $file->read($file->length));
@@ -98,7 +103,7 @@ class FileSystemTest extends TestCase
 
     public function testChar()
     {
-        $file = new FileStream(WORKING_DIR . '/file', FileStream::MODE_READ);
+        $file = new FileStream($this->workingDirectory . '/file', FileStream::MODE_READ);
         $this->assertInstanceOf(FileStream::class, $file);
 
         $file->seek(3, FileStream::ORIGIN_BEGIN);
@@ -109,16 +114,16 @@ class FileSystemTest extends TestCase
 
     public function testDirectoryFiles()
     {
-        $dir = new Directory(WORKING_DIR);
-        $this->assertEquals([realpath(WORKING_DIR . DIRECTORY_SEPARATOR . 'file')], $dir->files());
+        $dir = new Directory($this->workingDirectory);
+        $this->assertEquals([realpath($this->workingDirectory . DIRECTORY_SEPARATOR . 'file')], $dir->files());
     }
 
     public function testDelete()
     {
-        File::delete(WORKING_DIR . '/file');
-        $this->assertFalse(File::exists(WORKING_DIR . '/file'));
+        File::delete($this->workingDirectory . '/file');
+        $this->assertFalse(File::exists($this->workingDirectory . '/file'));
 
-        Directory::delete(WORKING_DIR);
-        $this->assertFalse(Directory::exists(WORKING_DIR));
+        Directory::delete($this->workingDirectory);
+        $this->assertFalse(Directory::exists($this->workingDirectory));
     }
 }
diff --git a/tests/UserTest.php b/tests/UserTest.php
index bc30347d..1e61268b 100644
--- a/tests/UserTest.php
+++ b/tests/UserTest.php
@@ -14,5 +14,6 @@ class UserTest extends TestCase
         $this->assertEquals(User::validateUsername('flaaaaaaaaaaaaaaaash'), 'long');
         $this->assertEquals(User::validateUsername('F|@$h'), 'invalid');
         $this->assertEquals(User::validateUsername('fl ash_wave'), 'spacing');
+        $this->assertEquals(User::validateUsername('fl  ash'), 'double-spaces');
     }
 }