atk4\data\tests\FieldTest::testDirty1 PHP Method

    public function testDirty1()
    {
        $m = new Model();
        $m->addField('foo', ['default' => 'abc']);
        $this->assertEquals(false, $m->isDirty('foo'));
        $m['foo'] = 'abc';
        $this->assertEquals(false, $m->isDirty('foo'));
        $m['foo'] = 'bca';
        $this->assertEquals(true, $m->isDirty('foo'));
        $m['foo'] = 'abc';
        $this->assertEquals(false, $m->isDirty('foo'));
        // set initial data
        $m->data['foo'] = 'xx';
        $this->assertEquals(false, $m->isDirty('foo'));
        $m['foo'] = 'abc';
        $this->assertEquals(true, $m->isDirty('foo'));
        $m['foo'] = 'bca';
        $this->assertEquals(true, $m->isDirty('foo'));
        $m['foo'] = 'xx';
        $this->assertEquals(false, $m->isDirty('foo'));
    }