1 # Test Subsystem ChangeLog
2 
3 ## cl.testfwk_arkxtest.1 Exception Handling Support of On, Driver, and Component APIs
4 
5 The original APIs in API version 8 are deprecated, and substitute APIs that support exception handling are introduced in API version 9. You must use **try catch** to capture exceptions thrown by the APIs.
6 
7 ## Change Impacts
8 
9 This change affects the JS APIs in API version 9 provided by **@ohos.uitest**. If you have used the API of **@ohos.uitest-api9** during test case development, adaptation is required so that the compilation can be successful in the SDK environment of the new version.
10 
11 ## Key API/Component Changes
12 
13 - The **By** class in API version 8 is deprecated and replaced by the **On** class in API version 9. The APIs of the **On** class support exception handling and retain their original name, with the exception of **By#key**, which is renamed **On.id**.
14 - The **BY** object in API version 8 is deprecated and replaced by the **ON** object in API version 9.
15 - The **UiDriver** class in API version 8 is deprecated and replaced by the **Driver** class in API version 9. The APIs of the **Driver** class support exception handling and retain their original name.
16 - The **UiComponent** class in API version 8 is deprecated and replaced by the **Component** class in API version 9. The APIs of the **Component** class support exception handling and retain their original name.
17 
18 ## Adaptation Guide
19 
20 1. Adapt to the API name changes.
21 
22    You can replace the class name according to the following rules:
23 
24    - `By-->On`
25    - `BY-->ON`
26    - `UiDriver-->Driver`
27    - `UiComponent-->Component`
28 
29 2. Catch and handle exceptions.
30 
31    Use **try-catch** to catch and handle exceptions thrown by the APIs. Below is the sample code:
32 
33    ```typescript
34    import {Driver,ON,Component} from '@ohos.uitest'
35 
36    try {
37        let driver = Driver.create();
38    } catch (error) {
39        // error handle; error.code indicates the error code.
40    }
41    ```