CustomTreeSection

The 'custom' tree section, usually contributed by extensions as TreeView. All The behaviour is defined by the general ViewSection class.

Lookup

import { SideBarView, CustomTreeSection } from 'vscode-extension-tester';
...
// Type is inferred automatically, the type cast here is used to be more explicit
const section = await new SideBarView().getContent().getSection('servers') as CustomTreeSection;