Unit Testing

Unit testing can be done by using the Dom::assert_eq function, which tests your DOM against a certain XML string:

struct DataModel;

fn render_counter(count: usize) -> Dom<DataModel> {
     Dom::div().with_class("test").with_child(
          Dom::label(format!("{}", count))
     )
}

#[test]
fn test_counter_ui() {
    let expected = r#"
        <div class="test">
            <p>5</p>
        </div>
    "#;

    let dom = render_counter(5);

    dom.assert_eq(expected);
}

You can technically also use assert_eq!(expected, got);, however, if the test fails, the Dom::assert_eq error message has a much nicer format:

thread 'widgets::test_counter_ui' panicked at '
Expected DOM did not match:

expected: ----------
<div/>
    <div class="test"/>
        <p>4</p>
    </div>
</div>

got: ----------
<div/>
    <div class="test"/>
        <p>5</p>
    </div>
</div>

Good Practices

• Typedef the name of your DataModel in your main.rs, so that it it easier to change in future projects.
• It's also a good idea to typedef the &'a AppState<DataModel> and the &'a mut CallbackInfo, in order to keep the code cleaner:

pub type DataModel = AppData;
pub type State<'a> = &'a mut AppState<DataModel>;
pub type CbInfo<'a, 'b> = &'a mut CallbackInfo<'b, DataModel>;

This way you can avoid a bit of typing work since rustc is smart enough to infer the lifetimes - your callbacks should now look like this:

fn my_callback(state: State, cb: CbInfo) -> Dom<DataModel> { /* */ }

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