PHPUnit_Framework_Constraint_ArrayHasKey::toString PHP Method

    public function toString()
    {
        return 'has the key ' . PHPUnit_Util_Type::toString($this->key);
    }

 public function testConstraintArrayHasKey()
 {
     $constraint = new PHPUnit_Framework_Constraint_ArrayHasKey(0);
     $this->assertFalse($constraint->evaluate(array()));
     $this->assertEquals('has key <integer:0>', $constraint->toString());
     try {
         $constraint->fail(array(), '');
     } catch (PHPUnit_Framework_ExpectationFailedException $e) {
         $this->assertEquals("Failed asserting that \nArray\n(\n)\n has key <integer:0>.", $e->getDescription());
         return;
     }
     $this->fail();
 }