public function testset_string()
{
$string = new williamknauss\String();
//assert 1
$this->assertEquals("", $string->return_string());
$string->set_string("Hello World");
//assert 2
$this->assertEquals("Hello World", $string->return_string());
//assert 3
$this->assertEquals(2, $string->evolution_counter());
$string->set_string("Goodbye World");
//assert 4
$this->assertEquals("Goodbye World", $string->return_string());
//assert 5
$this->assertEquals(3, $string->evolution_counter());
$string->set_string("Hello Again", true);
//assert 6
$this->assertEquals("Hello Again", $string->return_string());
//assert 7
$this->assertEquals(1, $string->evolution_counter());
$string->set_string("It's a fine day.")->set_string("Final Goodbye");
//assert 8
$this->assertEquals("Final Goodbye", $string->return_string());
//assert 9
$this->assertEquals(3, $string->evolution_counter());
}
