add Dont/ToString

Author: OskarStark

.travis.yml

@@ -1,9 +1,7 @@
 language: php
 
 php:
-  - 7.1
-  - 7.2
-  - 7.3
+  - 7.4
 
 before_script:
   - composer update

README.md

@@ -27,6 +27,7 @@ The package currently provides the following traits:
  * `Dont\DontSet`
  * `Dont\DontCall`
  * `Dont\DontCallStatic`
+ * `Dont\DontToString` 
  * `Dont\JustDont`
 
 Usage is straightforward:
@@ -45,5 +46,5 @@ serialize(new MyClass); // will throw an exception
 The same applies to `DontDeserialise`, but this
 time with `unserialize()`.
 
-`Dont\JustDont` includes other seven traits and is the recommended one to use.
+`Dont\JustDont` includes other eight traits and is the recommended one to use.
 

composer.json

@@ -16,7 +16,7 @@
         }
     ],
     "require": {
-        "php": "^7.1"
+        "php": "^7.4"
     },
     "require-dev": {
         "phpunit/phpunit": "^7.5 || ^8.0",

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 NonCloneableObject
+     * @throws TypeError
+     */
+    final public function __toString() : string
+    {
+        throw NonStringableObject::fromAttemptedToString($this);
+    }
+}

src/Dont/Exception/NonStringableObject.php

@@ -0,0 +1,38 @@
+<?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;
+
+    /**
+     * @param object $object
+     *
+     * @return NonStringableObject
+     *
+     * @throws TypeError
+     */
+    public static function fromAttemptedToString($object) : self
+    {
+        if (! is_object($object)) {
+            throw TypeError::fromNonObject($object);
+        }
+
+        $className = get_class($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/NonStringableObjectTest.php

@@ -0,0 +1,78 @@
+<?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],
+        ];
+    }
+
+    /**
+     * @dataProvider nonObjectProvider
+     *
+     * @param mixed $nonObject
+     */
+    public function testWillThrowOnNonObject($nonObject) : void
+    {
+        $this->expectException(TypeError::class);
+
+        NonStringableObject::fromAttemptedToString($nonObject);
+    }
+
+    /**
+     * @return mixed[][]
+     */
+    public function nonObjectProvider() : array
+    {
+        return [
+            [null],
+            [true],
+            [123],
+            [12.3],
+            ['foo'],
+            [[]],
+            [STDERR],
+        ];
+    }
+}

tests/DontTestAsset/NonStringable.php

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