message: test: add test for npm run build
diff: 'use strict';
  import * as assert from 'assert';
  +import { spawnSync } from 'child_process';
  import * as fs from 'fs';
  import * as os from 'os';
  import * as path from 'path';
  @@ -24,6 +25,15 @@ describe('generator', () => {
  fs.readFileSync(path.resolve(__dirname, 'manifest.json'), 'utf8')
  );
  generatePlugin(outputDir, manifest, 'ja');
  +
  + // test that `npm run build` doesn't fail
  + const buildResult = spawnSync('npm', ['run', 'build'], {
  + cwd: outputDir,
  + stdio: 'inherit',
  + shell: true
  + });
  + assert(buildResult.status === 0);
  +
  assert.deepStrictEqual(
  JSON.parse(
  fs.readFileSync(path.resolve(outputDir, 'src', 'manifest.json'), 'utf8')
  