Its not about Appium.. Its about ur test case logic and framework.
Ideally ur test script should be written such that, you pass all the test data in proper format. [Ex : Whether to apply discount, if applied what is the final price, what is the shipping address you are setting]
Once you pass these data to your test case, it can be asserted against the value shown in screen[by using Appium findElement api]
example code :
String expectedAddressLine1 = "Test 1";
String actualAddressLine1 = driver.findElementById("xyz").getText();
Assert.assertTrue(expectedAddressLine1.equalsIgnoreCase(actualAddressLine1), "Address Mismatch!")
Note : I am using TestNG Assert class above.