use mock requests for better reliability and isolation

.gitignore

@@ -23,3 +23,6 @@ clover.xml
 
 # Ignore PHPUnit cache file
 .phpunit.result.cache
+
+# Ignore PHP-CS-Fixer cache file
+.php-cs-fixer.cache

lib/PayjpObject.php

@@ -58,14 +58,6 @@ public function __construct($id = null, $opts = null)
     // Standard accessor magic methods
     public function __set($k, $v)
     {
-        if ($v === "") {
-            throw new InvalidArgumentException(
-                'You cannot set \''.$k.'\'to an empty string. '
-                .'We interpret empty strings as NULL in requests. '
-                .'You may set obj->'.$k.' = NULL to delete the property'
-            );
-        }
-
         if (self::$nestedUpdatableAttributes->includes($k)
                 && isset($this->$k) && is_array($v)) {
             $this->$k->replaceWith($v);

lib/Util/Util.php

@@ -8,6 +8,7 @@ abstract class Util
 {
     // todo wanna use 'private const' (only PHP >= v7.1.0)
     private static $types = array(
+        'account' => \Payjp\Account::class,
         'application_url' => \Payjp\ApplicationUrl::class,
         'balance' => \Payjp\Balance::class,
         'card' => \Payjp\Card::class,

tests/AccountTest.php

@@ -6,7 +6,7 @@ class AccountTest extends TestCase
 {
     private function managedAccountResponse($id)
     {
-        return [
+        $data = [
             'accounts_enabled' => [
                 'merchant',
                 'customer',
@@ -80,15 +80,27 @@ private function managedAccountResponse($id)
             ],
             'object' => 'account'
         ];
+        return $data;
     }
 
     public function testBasicRetrieve()
     {
         $this->mockRequest('GET', '/v1/accounts', [], $this->managedAccountResponse('acct_ABC'));
         $account = Account::retrieve();
 
+        $this->assertInstanceOf('Payjp\Account', $account);
         $this->assertSame('acct_ABC', $account->id);
+
+        $this->assertInstanceOf('Payjp\PayjpObject', $account->customer);
         $this->assertSame('acct_cus_38153121efdb7964dd1e147', $account->customer->id);
+
+        $this->assertInstanceOf('Payjp\PayjpObject', $account->merchant);
         $this->assertSame('acct_mch_002418151ef82e49f6edee1', $account->merchant->id);
+
+        $this->assertInstanceOf('Payjp\Collection', $account->customer->cards);
+        $this->assertTrue(is_array($account->customer->cards->data));
+        $this->assertCount(1, $account->customer->cards->data);
+        $this->assertInstanceOf('Payjp\Card', $account->customer->cards->data[0]);
+        $this->assertSame('car_99abf74cb5527ff68233a8b836dd', $account->customer->cards->data[0]->id);
     }
 }

tests/AuthenticationErrorTest.php

@@ -7,6 +7,10 @@ class AuthenticationErrorTest extends TestCase
     public function testInvalidCredentials()
     {
         Payjp::setApiKey('invalid');
+        $mock = $this->setUpMockRequest();
+        $mock->expects($this->once())
+            ->method('request')
+            ->willThrowException(new Error\Authentication('Invalid API Key', 401));
         try {
             Customer::create();
         } catch (Error\Authentication $e) {

tests/BalanceTest.php

@@ -165,8 +165,16 @@ public function testRetrieve()
         $this->assertSame($expectedBalanceResource['statements']['object'], $balance->statements->object);
         $this->assertSame($expectedBalanceResource['statements']['url'], $balance->statements->url);
 
-        foreach ($balance->statements->data as $statement) {
+        $expectedStatementsData = $expectedBalanceResource['statements']['data'];
+        foreach ($balance->statements->data as $index => $statement) {
             $this->assertInstanceOf(Statement::class, $statement);
+            $this->assertSame($expectedStatementsData[$index]['id'], $statement->id);
+            if (isset($expectedStatementsData[$index]['term']) && $expectedStatementsData[$index]['term'] !== null) {
+                $this->assertInstanceOf(PayjpObject::class, $statement->term); // Assuming Term becomes PayjpObject
+                $this->assertSame($expectedStatementsData[$index]['term']['id'], $statement->term->id);
+            } else {
+                $this->assertNull($statement->term);
+            }
         }
     }
 

tests/CardErrorTest.php

@@ -16,7 +16,10 @@ public function testExpiredCard()
                 'cvc' => '314'
             ]
         ];
-
+        $mock = $this->setUpMockRequest();
+        $mock->expects($this->once())
+            ->method('request')
+            ->willThrowException(new Error\Card('Expired card', null, 'expired_card', 402, null, null));
         try {
             Token::create($params, ['payjp_direct_token_generate' => 'true']);
         } catch (Error\Card $e) {