Merge pull request #32 from afilina/dont-__toString

add Dont/ToString

Author: Ocramius

README.md

@@ -25,6 +25,7 @@ The package currently provides the following traits:
  * [`Dont\DontSet`](docs/DontSet.md)
  * [`Dont\DontCall`](docs/DontCall.md)
  * [`Dont\DontCallStatic`](docs/DontCallStatic.md)
+ * [`Dont\DontToString`](docs/DontToString.md)
  * [`Dont\JustDont`](docs/JustDont.md)
 
 Usage is straightforward:

docs/DontToString.md

@@ -0,0 +1,13 @@
+# DontToString
+
+Prevent converting an object as a string.
+
+```php
+use Dont\DontToString;
+
+class MyClass
+{
+    use DontToString;
+}
+(new MyClass)->__toString(); // will throw NonStringableObject exception
+```

src/Dont/DontToString.php

@@ -0,0 +1,21 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Dont;
+
+use Dont\Exception\NonCloneableObject;
+use Dont\Exception\NonStringableObject;
+use Dont\Exception\TypeError;
+
+trait DontToString
+{
+    /**
+     * @throws NonStringableObject
+     * @throws TypeError
+     */
+    final public function __toString() : string
+    {
+        throw NonStringableObject::fromAttemptedToString($this);
+    }
+}

src/Dont/Exception/NonStringableObject.php

@@ -0,0 +1,30 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Dont\Exception;
+
+use LogicException;
+
+class NonStringableObject extends LogicException implements ExceptionInterface
+{
+    private const ERROR_TEMPLATE = <<<'ERROR'
+The given object %s#%s is not designed to be stringable.
+
+You tried to access a method called "__toString()".
+ERROR;
+
+    /**
+     * @return NonStringableObject
+     */
+    public static function fromAttemptedToString(object $object) : self
+    {
+        $className = get_class($object);
+
+        return new self(sprintf(
+            self::ERROR_TEMPLATE,
+            $className,
+            spl_object_hash($object)
+        ));
+    }
+}

src/Dont/JustDont.php

@@ -13,4 +13,5 @@ trait JustDont
     use DontClone;
     use DontSerialise;
     use DontDeserialise;
+    use DontToString;
 }

tests/DontTest/DontToStringTest.php

@@ -0,0 +1,57 @@
+<?php
+
+declare(strict_types=1);
+
+namespace DontTest;
+
+use Dont\DontToString;
+use Dont\Exception\NonStringableObject;
+use DontTestAsset\DontDoIt;
+use DontTestAsset\NonStringable;
+use PHPUnit\Framework\TestCase;
+
+/**
+ * @covers \Dont\DontToString
+ */
+final class DontToStringTest extends TestCase
+{
+    /**
+     * @dataProvider nonStringableObject
+     *
+     * @param object $object
+     */
+    public function testWillThrowOnToStringMethodAttempt($object) : void
+    {
+        $this->expectException(NonStringableObject::class);
+
+        $object->__toString();
+    }
+
+    /**
+     * @dataProvider nonStringableObject
+     *
+     * @param object $object
+     */
+    public function testWillThrowOnStringCastAttempt($object) : void
+    {
+        $this->expectException(NonStringableObject::class);
+
+        (string) $object;
+    }
+
+    /**
+     * @return object[]
+     */
+    public function nonStringableObject() : array
+    {
+        return [
+            [new NonStringable()],
+            [new DontDoIt()],
+        ];
+    }
+
+    public function testToStringPreventionIsFinal() : void
+    {
+        self::assertTrue((new \ReflectionMethod(DontToString::class, '__toString'))->isFinal());
+    }
+}

tests/DontTest/Exception/NonCallableObjectTest.php

@@ -75,5 +75,4 @@ public function nonObjectProvider() : array
             [STDERR],
         ];
     }
-
-}
+}

tests/DontTest/Exception/NonStringableObjectTest.php

@@ -0,0 +1,50 @@
+<?php
+
+declare(strict_types=1);
+
+namespace DontTest\Exception;
+
+use Dont\Exception\ExceptionInterface;
+use Dont\Exception\NonCloneableObject;
+use Dont\Exception\NonStringableObject;
+use Dont\Exception\TypeError;
+use LogicException;
+use PHPUnit\Framework\TestCase;
+use stdClass;
+
+/**
+ * @covers \Dont\Exception\NonStringableObject
+ */
+final class NonStringableObjectTest extends TestCase
+{
+    /**
+     * @dataProvider objectProvider
+     *
+     * @param object $object
+     */
+    public function testFromAttemptedCloning($object) : void
+    {
+        $exception = NonStringableObject::fromAttemptedToString($object);
+
+        self::assertInstanceOf(NonStringableObject::class, $exception);
+        self::assertInstanceOf(LogicException::class, $exception);
+        self::assertInstanceOf(ExceptionInterface::class, $exception);
+
+        $expected = 'The given object ' . get_class($object)
+            . '#' . spl_object_hash($object) . " is not designed to be stringable.\n\n"
+            . "You tried to access a method called \"__toString()\".";
+
+        self::assertSame($expected, $exception->getMessage());
+    }
+
+    /**
+     * @return object[][]
+     */
+    public function objectProvider() : array
+    {
+        return [
+            [new stdClass()],
+            [$this],
+        ];
+    }
+}

tests/DontTestAsset/NonStringable.php

@@ -0,0 +1,12 @@
+<?php
+
+declare(strict_types=1);
+
+namespace DontTestAsset;
+
+use Dont\DontToString;
+
+final class NonStringable
+{
+    use DontToString;
+}