title: Testing a vscode extension that depends on another one
body: <p>I'm trying to write a test for an extension. The extension uses the python extension (ms-python.python).
  Therefore I put this in my package.json:</p>
  <pre><code>&quot;extensionDependencies&quot;: [
      &quot;ms-python.python&quot;
  ],
  </code></pre>
  <p>To be able to run my test I need &quot;ms-python.python&quot; to be installed. I followed this documentation:
  <a href="https://code.visualstudio.com/api/working-with-extensions/testing-extension#custom-setup-with-vscodetestelectron" rel="nofollow noreferrer">https://code.visualstudio.com/api/working-with-extensions/testing-extension#custom-setup-with-vscodetestelectron</a></p>
  <p>but for some reason I can't make it work.
  When running my test with 'npm run test':</p>
  <pre><code>import * as path from 'path';
  import * as cp from 'child_process';
  import { downloadAndUnzipVSCode, resolveCliPathFromVSCodeExecutablePath, runTests } from '@vscode/test-electron';
  import * as fs from 'fs-extra';
  import * as rimraf from 'rimraf';
  
  
  async function main() {
  
      const tmpHomeDir: string = fs.mkdtempSync(&quot;/tmp/vscode-tests&quot;);
      try {
          const workspaceSettingsPath = path.resolve(__dirname, '../../src/test/compile/workspace/.vscode/settings.json');
          await fs.ensureFile(workspaceSettingsPath);
  
          // The folder containing the Extension Manifest package.json
          // Passed to `--extensionDevelopmentPath`
          const extensionDevelopmentPath = path.resolve(__dirname, '../../');
  
          const vscodeExecutablePath = await downloadAndUnzipVSCode('1.50.0');
          const cliPath = resolveCliPathFromVSCodeExecutablePath(vscodeExecutablePath);
          cp.spawnSync(cliPath, ['--install-extension', 'ms-python.python'], {
              encoding: 'utf-8',
              stdio: 'inherit'
          });
  
          await runTests({
              vscodeExecutablePath,
              extensionDevelopmentPath: extensionDevelopmentPath,
              extensionTestsPath: path.resolve(__dirname, './compile/index'),
              launchArgs: [path.resolve(__dirname, '../../src/test/compile/workspace')],
          });
      } catch (err) {
          console.error('Failed to run tests: ' + err);
          process.exit(1);
      } finally {
          rimraf.sync(tmpHomeDir);
      }
  }
  
  main();
  </code></pre>
  <p>This start a new vscode(Extension Development Host)but with a message saying:</p>
  <blockquote>
  <p>Cannot activate the 'xxx' extension because it depends on the 'Python'
  extension, which is not installed. Would you like to install the
  extension and reload the window?</p>
  </blockquote>
  <p>So it seems the Python extension was not installed, or not where it should...</p>
  <p>Thanks in advance for the help :)</p>