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Tips on writing Tast tests

How to view accessibility tree

Problem

I want to know what elements I can obtain for tast end to end test.

Solution

Solution 1:

Tast test's ui automation API is based on accessibility DOM tree. To view full accessibility tree, follow this guide in the chrome devtool. Full accessibility tree in Chrome DevTools.

Solution 2:

Print out the full a11y tree in a tast test.

s.Log(uiauto.RootDebugInfo(ctx, tconn))

How to obtain a button and verify if it exists

Problem

I want to verify if a button exists.

Solution

button := nodewith.Name("Continue").Role(role.Button)
if err := ui.WithTimeout(20 * time.Second).WaitUntilExists(button)(ctx); err != nil {
    s.Fatal("Failed to click continue button: ", err)
}

Some buttons appear as a button in the a11y tree, but if you look them up by role.Button, you won't be able to find them. For example, the "More…" button in the files app should be looked up by role.PopUpButton. If you are looking for a button and can't find it, try to remove the role and look it up by the name only.

Example CL

References

How to mock a mouse click action

Problem

I want to mock a mouse click action.

Solution

Use DoDefault whenever possible, e.g. if the node is a Button.

button := nodewith.Name("Continue").Role(role.Button)
if err := ui.DoDefault(button); err != nil {
    s.Fatal("Failed to click continue button: ", err)
}

For some nodes, e.g. GenericContainer, the DoDefault function does something else instead of clicking. In these cases, use LeftClick. It is more flaky, so only use if DoDefault doesn't work.

feedbackShortcut := nodewith.NameContaining("Send feedback").Role(role.GenericContainer)
if err := ui.LeftClick(feedbackShortcut)(ctx); err != nil {
    s.Fatal("Failed to click feedback shortcut: ", err)
}

In the above examples, we obtain the node first, then click on it.

Example CLs

References

How to mock keyboard typing

Problem

I want to mock a keyboard typing action.

Solution

Solution 1: here we mock the keyboard typing an issue description: "I am not able to connect to bluetooth".

// Set up keyboard.
kb, err := input.Keyboard(ctx)
if err != nil {
    s.Fatal("Failed to find keyboard: ", err)
}
defer kb.Close()

// Enter issue description.
if err := kb.Type(ctx, "I am not able to connect to bluetooth"); err != nil {
    s.Fatal("Failed to enter issue description: ", err)
}

Sometimes it is useful to make sure that the text field is loaded before the typing starts. If you run the test and don't see any input, try this.

searchBar := nodewith.NameContaining("Search settings").Role(role.SearchBox)
if err := ui.WaitUntilExists(searchBar)(ctx); err != nil {
    s.Fatal("Failed to find search bar: ", err)
}

// Search for "feedback" in the settings search bar.
if err := kb.Type(ctx, "feedback"); err != nil {
    s.Fatal("Failed to type search query: ", err)
}

NOTE: you don't need to WaitUntilExists when using DoDefault and LeftClick, because it's baked into those functions.

Solution 2: here we mock the keyboard typing a shortcut Alt+Shift+I.

if err := kb.Accel(ctx, "Alt+Shift+I"); err != nil {
    s.Fatal("Failed pressing alt+shift+i: ", err)
}

Example CLs

References

How to verify an attribute value

Problem

I want to verify if a checkbox is checked.

Solution

// Verify share url checkbox is checked by default.
checkboxAncestor := nodewith.NameContaining("Share URL").Role(
  role.GenericContainer).Ancestor(feedbackRootNode)
checkbox := nodewith.Role(role.CheckBox).Ancestor(checkboxAncestor)
if err := ui.WaitUntilExists(checkbox.Attribute("checked", "true"))(ctx); err != nil {
  s.Fatal("Failed to find checked share url checkbox: ", err)
}

In the above example, we obtain the checkbox ancestor first, which is a cr-checkbox, then select the checkbox. We can use Attribute function to verify if the checked attribute is true.

Example CL

References

How to obtain node name value

Problem

I want to obtain the link name value.

Solution

currentNodeInfo, err := ui.Info(ctx, link)
if err != nil {
    return errors.Wrap(err, "failed to find the first link info during update")
}
currentName := currentNodeInfo.Name

In the above example, we call ui.Info function first to get the currentNodeInfo object. In this object the Name attribute has the string value for this link.

Example CL

References

How to wait for a process to complete

Problem

I need to wait for a running process to complete before continuing.

Solution

    proc, err := procutil.FindUnique(procutil.ByExe("/path/to/exe"))
	if err != nil {
		s.Fatal("Process did not start: ", err)
	}
    if err := procutil.WaitForTerminated(ctx, proc, 2*time.Minute); err != nil {
        s.Fatal("Process did not stop: ", err)
    }

In the above example a process is already running and WaitForTerminated polls until the process is no longer running or timeout occurs. until the process is no longer running or timeout occurs.

Example CL

References

How call mojo-remote from tast

Problem

I need to trigger JS mojo function from the test.

Solution

// SystemDataProviderMojoAPI returns a MojoAPI object that is connected to a SystemDataProvider
// mojo remote instance on success, or an error.
func SystemDataProviderMojoAPI(ctx context.Context, conn *chrome.Conn) (*MojoAPI, error) {
	var mojoRemote chrome.JSObject
	if err := conn.Call(ctx, &mojoRemote, systemDataProviderJs); err != nil {
		return nil, errors.Wrap(err, "failed to set up the SystemDataProvider mojo API")
	}

	return &MojoAPI{conn, &mojoRemote}, nil
}

// RunFetchSystemInfo calls into the injected SystemDataProvider mojo API.
func (m *MojoAPI) RunFetchSystemInfo(ctx context.Context) error {
	jsWrap := "function() { return this.fetchSystemInfo() }"
	if err := m.mojoRemote.Call(ctx, nil, jsWrap); err != nil {
		return errors.Wrap(err, "failed to run fetchSystemInfo")
	}

	return nil
}

Note: Works for mojo which is loaded into the frontend as "mojom-lite" or "mojom-webui". If using "mojom-webui" you will need to programmatically load the module you want to interact with. "mojom-lite" loads the mojo API onto the window.

Example CL

References

How to add name to generic element

Problem

I need to add name to generic element in a11y tree.

Solution

Example CL