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Validating Production Build Path Resolution in Create-React-App

This test suite validates the handling of relative paths in production builds for Create React App. It specifically focuses on ensuring correct path resolution between CSS and SVG files after the build process is complete.

Test Coverage Overview

The test coverage focuses on verifying the integrity of file paths in production builds. Key functionality includes:

Production build path resolution
CSS-to-SVG file reference validation
URL pattern extraction and verification
Path normalization checks

Implementation Analysis

The testing approach employs Jest’s async/await pattern for build script execution and path validation. It utilizes fs-extra for file operations and globby for file pattern matching, implementing a systematic verification of build artifacts and their relationships.

The test specifically examines URL patterns within CSS files and validates their resolution against actual SVG file locations.

Technical Details

Testing Framework: Jest
File System: fs-extra
Path Handling: Node.js path module
File Pattern Matching: globby
Build Script: Custom test setup utilities
Assertion Pattern: Jest expect statements

Best Practices Demonstrated

The test exemplifies robust production build validation practices through careful path resolution handling. Notable practices include:

Asynchronous test execution
File system abstraction
Regular expression pattern matching
Path normalization for cross-platform compatibility
Isolated test environment setup

facebook/create-react-app

test/fixtures/relative-paths/index.test.js

            
'use strict';

const testSetup = require('../__shared__/test-setup');

const fs = require('fs-extra');
const globby = require('globby');
const path = require('path');

test('contains a relative path in production build', async () => {
  await testSetup.scripts.build();

  const buildDir = path.join(testSetup.testDirectory, 'build');
  const cssFile = path.join(
    buildDir,
    globby.sync('**/*.css', { cwd: buildDir }).pop()
  );
  const svgFile = path.join(
    buildDir,
    globby.sync('**/*.svg', { cwd: buildDir }).pop()
  );
  const desiredPath = /url\((.+?)\)/
    .exec(fs.readFileSync(cssFile, 'utf8'))
    .pop();
  expect(path.resolve(path.join(path.dirname(cssFile), desiredPath))).toBe(
    path.resolve(svgFile)
  );
});