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Testing ETag Header Implementation in koajs/koa

This test suite validates the ETag header functionality in Koa’s response handling. It ensures proper formatting and manipulation of ETag values, which are crucial for HTTP caching mechanisms and content validation.

Test Coverage Overview

The test suite provides comprehensive coverage of ETag header handling in HTTP responses.

Key areas tested include:

Preservation of properly quoted ETags
Handling of weak ETags with W/ prefix
Automatic quoting of unquoted ETag values
Getter functionality for ETag values

Implementation Analysis

The testing approach uses Node’s native test framework with focused unit tests for ETag manipulation. The implementation employs straightforward assertion patterns to verify header modifications and value retrievals.

Technical patterns include:

Response object isolation using test helpers
Direct header value comparisons
Getter/setter verification patterns

Technical Details

Testing infrastructure includes:

Node.js native test framework (node:test)
Assert module for validations
Custom test helpers for response context
Isolated response object creation

Best Practices Demonstrated

The test suite exemplifies several testing best practices in Node.js applications.

Notable practices include:

Isolated test cases with clear objectives
Consistent test structure and naming
Proper setup and context management
Comprehensive edge case coverage
Clear assertion messages

koajs/koa

__tests__/response/etag.test.js

            
'use strict'

const { describe, it } = require('node:test')
const assert = require('assert')
const response = require('../../test-helpers/context').response

describe('res.etag=', () => {
  it('should not modify an etag with quotes', () => {
    const res = response()
    res.etag = '"asdf"'
    assert.strictEqual(res.header.etag, '"asdf"')
  })

  it('should not modify a weak etag', () => {
    const res = response()
    res.etag = 'W/"asdf"'
    assert.strictEqual(res.header.etag, 'W/"asdf"')
  })

  it('should add quotes around an etag if necessary', () => {
    const res = response()
    res.etag = 'asdf'
    assert.strictEqual(res.header.etag, '"asdf"')
  })
})

describe('res.etag', () => {
  it('should return etag', () => {
    const res = response()
    res.etag = '"asdf"'
    assert.strictEqual(res.etag, '"asdf"')
  })
})