npm i -D jest

{
  "scripts": {
    "test": "jest"
  }
}

// vscode.js

const languages = {
  createDiagnosticCollection: jest.fn()
};

const StatusBarAlignment = {};

const window = {
  createStatusBarItem: jest.fn(() => ({
    show: jest.fn()
  })),
  showErrorMessage: jest.fn(),
  showWarningMessage: jest.fn(),
  createTextEditorDecorationType: jest.fn()
};

const workspace = {
  getConfiguration: jest.fn(),
  workspaceFolders: [],
  onDidSaveTextDocument: jest.fn()
};

const OverviewRulerLane = {
  Left: null
};

const Uri = {
  file: f => f,
  parse: jest.fn()
};
const Range = jest.fn();
const Diagnostic = jest.fn();
const DiagnosticSeverity = { Error: 0, Warning: 1, Information: 2, Hint: 3 };

const debug = {
  onDidTerminateDebugSession: jest.fn(),
  startDebugging: jest.fn()
};

const commands = {
  executeCommand: jest.fn()
};

const vscode = {
  languages,
  StatusBarAlignment,
  window,
  workspace,
  OverviewRulerLane,
  Uri,
  Range,
  Diagnostic,
  DiagnosticSeverity,
  debug,
  commands
};

module.exports = vscode;

// git-mob-hook-status.spec.js

const { hasPrepareCommitMsgTemplate } = require("../prepare-commit-msg-file");
const { gitMobHookStatus } = require("./git-mob-hook-status");

jest.mock("./../prepare-commit-msg-file");

describe("Hook or template status", function() {
  let mockContext;
  beforeAll(function() {
    mockContext = {
      subscriptions: []
    };
  });

  afterEach(function() {
    hasPrepareCommitMsgTemplate.mockReset();
  });

  it("using git template for co-authors", () => {
    hasPrepareCommitMsgTemplate.mockReturnValue(false);
    const statusBar = gitMobHookStatus({ context: mockContext })();
    expect(statusBar).toEqual(
      expect.objectContaining({
        text: "$(file-code) Git Mob",
        tooltip: "Using .gitmessage template"
      })
    );
  });

  it("using git prepare commit msg for co-authors", () => {
    hasPrepareCommitMsgTemplate.mockReturnValue(true);
    const statusBar = gitMobHookStatus({ context: mockContext })();
    expect(statusBar).toEqual(
      expect.objectContaining({
        text: "$(zap) Git Mob",
        tooltip: "Using prepare-commit-msg hook"
      })
    );
  });
});

// git-mob-hook-status.js
const vscode = require("vscode");
const { hasPrepareCommitMsgTemplate } = require("../prepare-commit-msg-file");

function gitMobHookStatus({ context }) {
  const myStatusBarItem = vscode.window.createStatusBarItem(
    vscode.StatusBarAlignment.Left,
    10
  );
  context.subscriptions.push(myStatusBarItem);
  return function() {
    myStatusBarItem.text = "$(file-code) Git Mob";
    myStatusBarItem.tooltip = "Using .gitmessage template";
    if (hasPrepareCommitMsgTemplate()) {
      myStatusBarItem.text = "$(zap) Git Mob";
      myStatusBarItem.tooltip = "Using prepare-commit-msg hook";
    }
    myStatusBarItem.show();
    return myStatusBarItem;
  };
}

exports.gitMobHookStatus = gitMobHookStatus;

const vscode = require("../__mocks__/vscode");

// ...
test("Reload co-author list when git-coauthors file saved", () => {
  reloadOnSave(coAuthorProviderStub);
  expect(vscode.workspace.onDidSaveTextDocument).toHaveBeenCalledWith(
    expect.any(Function)
  );
  // ...
});
// ...