Mocking vscode API when unit testing in Jest

Question

Environment:

$ jest -v > 24.9.0
$ node -v > 10.15.3
"@types/vscode": "1.37.0"
"vscode": "^1.37.0"

Inspiration came from Unit test functions that use vscode extension api functions

The layer of indirection has solved part of my problem, However: I need to remove the following function from my extension code so that I can unit test without the dependency of vscode api:

await commands.executeCommand('vscode.open', uri);

The code is refactored to VscodeEnv as follows:

import { Uri, commands, ExtensionContext, WebviewPanel, Disposable } from 'vscode';

export type VSCodeWebviewPanel = WebviewPanel;
export { ExtensionContext as VSCodeExtensionContext };
export { Uri as VSCodeUri };

export class VscodeEnv {
    private static instance: VscodeEnv;
    private constructor() {
        // Nothing added
    }

    public static async executeCommand(command: string, ...rest: any[]): Promise<any | undefined> {
        return commands.executeCommand(command, rest);
    }

    public static registerCommand(command: string, callback: (...args: any[]) => any, thisArg: any): Disposable {
        return commands.registerCommand(command, callback, thisArg);
    }

    public static getInstance(): VscodeEnv {
        if (!VscodeEnv.instance) {
            VscodeEnv.instance = new VscodeEnv();
        }
        return VscodeEnv.instance;
    }
}

Commands are registered as follows:

       const openFileCommand = new OpenFileCmd();
        VscodeEnv.registerCommand(
            ExtensionConfig.Commands.OpenFile.cmd,
            async (uri: VSCodeUri) => openFileCommand.openFile(context, uri.fsPath || ''), this);

And commands are executed as follows:

await VscodeEnv.executeCommand(ExtensionConfig.Commands.Display.cmd, editParams);

The following error message is thrown when I try to call executeCommand with the new flow:

No extension context

Still a few tweaks to incorporate Jest but it allows me to mock vscode API.

Any improvements would be appreciated or any idea why the context is empty?

Thanks.

Answer 1

The issue relates to the params being received by the callback method specified when registering the command:

VSCodeEnv.registerCommand(
            ExtensionConfig.Commands.OpenFile.cmd,
            async (uri: VSCodeUri) => openFileCommand.openFile([context, (uri && uri.fsPath) || '']),
            this
        );

Where the implementation needed to change to the following:

public async openFile(params: any[]): Promise<void> {

In order for object destructing to work.