old_contents: const postcss = require('postcss');
  const plugin = require('../index');
  const pkg = require('../package.json');
  const fs = require('fs');
  
  /**
   * Runs the plugins process function. Tests whether the given input is equal
   * to the expected output with the given options.
   *
   * @param {string} input Input fixture file name.
   * @param {object} opts Options to be used by the plugin.
   * @return {function}
   */
  function run(input, opts) {
      const raw = fs.readFileSync(`./test/fixtures/${input}.css`, 'utf8');
      const expected = fs.readFileSync(`./test/fixtures/${input}.expected.css`, 'utf8');
  
      return postcss([plugin(opts)]).process(raw)
          .then(result => {
              expect(result.css).toEqual(expected);
              expect(result.warnings().length).toBe(0);
          });
  }
  
  it('Should replace strings in comments and styles.', () => {
      return run('basic', { data: pkg });
  });
  
  it('Should not replace anything in styles when “commentsOnly” option is set to TRUE.', () => {
      return run('commentsOnly', { data: pkg, commentsOnly: true });
  });
  
  it('Should not replace anything without data', () => {
      return run('noChanges');
  });
  
  it('Should not change unknown variables', () => {
      return run('noChanges', { data: pkg });
  });
  
  it('Should work with deep data objects', () => {
      return run('deep', { data: { level1: { level2: 'test' } } });
  });
  
  it('Should work with a custom RegEx', () => {
      return run('otherRegEx', { data: pkg, pattern: /%\s?([^\s]+?)\s?%/gi });
  });
  
  it('Should work with a custom RegEx object', () => {
      return run('basic', { data: pkg, pattern: new RegExp(/{{\s?([^\s]+?)\s?}}/, 'gi') });
  });
  
  it('Should work with a custom RegEx string', () => {
      return run('basic', { data: pkg, pattern: '{{\\s?([^\\s]+?)\\s?}}' });
  });
  
  it('Should work with another custom RegEx string', () => {
      return run('otherRegEx', { data: pkg, pattern: '%\\s?([^\\s]+?)\\s?%' });
  });
  
new_contents: const postcss = require('postcss');
  const plugin = require('../index');
  const pkg = require('../package.json');
  const fs = require('fs');
  
  /**
   * Runs the plugins process function. Tests whether the given input is equal
   * to the expected output with the given options.
   *
   * @param {string} input Input fixture file name.
   * @param {object} opts Options to be used by the plugin.
   * @return {function}
   */
  function run(input, opts) {
      const raw = fs.readFileSync(`./test/fixtures/${input}.css`, 'utf8');
      const expected = fs.readFileSync(`./test/fixtures/${input}.expected.css`, 'utf8');
  
      return postcss([plugin(opts)]).process(raw)
          .then(result => {
              expect(result.css).toEqual(expected);
              expect(result.warnings().length).toBe(0);
          });
  }
  
  it('Should replace strings in comments and styles.', () => {
      return run('basic', { data: pkg });
  });
  
  it('Should not replace anything in styles when “commentsOnly” option is set to TRUE.', () => {
      return run('commentsOnly', { data: pkg, commentsOnly: true });
  });
  
  it('Should not replace anything without data', () => {
      return run('noChanges');
  });
  
  it('Should not change unknown variables', () => {
      return run('noChanges', { data: pkg });
  });
  
  it('Should work with deep data objects', () => {
      return run('deep', { data: { level1: { level2: 'test' } } });
  });
  
  it('Should work with a custom RegEx', () => {
      return run('otherRegex', { data: pkg, pattern: /%\s?([^\s]+?)\s?%/gi });
  });
  
  it('Should work with a custom RegEx object', () => {
      return run('basic', { data: pkg, pattern: new RegExp(/{{\s?([^\s]+?)\s?}}/, 'gi') });
  });
  
  it('Should work with a custom RegEx string', () => {
      return run('basic', { data: pkg, pattern: '{{\\s?([^\\s]+?)\\s?}}' });
  });
  
  it('Should work with another custom RegEx string', () => {
      return run('otherRegex', { data: pkg, pattern: '%\\s?([^\\s]+?)\\s?%' });
  });
  
subject: Fix wrong fixture filename in test