Q:

Validate if amount is changed - Selenium

I want to validate amount changing
for example: 
Balance = 1 and user adds 1
how  to validate that the balance will be 2? 
<div class="balance__amount">
    1 GEL
</div>

after adding +1 
<div class="balance__amount">
    2 GEL
</div>

A:

Use driver.findElement and compare the two innerHTMLs.  You might need another function for the calculating the result of balance + user input. 
Try starting with this:
driver.findElement(By.className('balance__amount')).getAttribute("innerHTML").then(
//do something
);

