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Testing Request Freshness Detection Implementation in koajs/koa

This test suite evaluates the freshness checking functionality in Koa’s request handling system. It verifies the behavior of the ctx.fresh property across different HTTP methods, response status codes, and ETag matching scenarios.

Test Coverage Overview

The test suite provides comprehensive coverage of the ctx.fresh property implementation.

Tests HTTP method conditions (GET/HEAD vs other methods)
Validates behavior for different response status codes (2xx vs non-2xx)
Verifies ETag matching scenarios
Covers edge cases in request/response combinations

Implementation Analysis

The testing approach uses Jest’s describe/it blocks for structured test organization. Each test case isolates specific conditions using a context helper, allowing precise control over request and response properties.

Uses strict assertion checking with node:test
Implements context isolation patterns
Follows BDD-style test structure

Technical Details

Testing Framework: Node.js built-in test runner
Assertion Library: Node.js assert module
Helper Utilities: Custom context creation
Test Environment: Node.js runtime
Structure: Nested describe blocks for categorical testing

Best Practices Demonstrated

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

Clear test case isolation
Consistent assertion patterns
Hierarchical test organization
Descriptive test naming
Focused test scenarios

koajs/koa

__tests__/request/fresh.test.js

            
'use strict'

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

describe('ctx.fresh', () => {
  describe('the request method is not GET and HEAD', () => {
    it('should return false', () => {
      const ctx = context()
      ctx.req.method = 'POST'
      assert.strictEqual(ctx.fresh, false)
    })
  })

  describe('the response is non-2xx', () => {
    it('should return false', () => {
      const ctx = context()
      ctx.status = 404
      ctx.req.method = 'GET'
      ctx.req.headers['if-none-match'] = '123'
      ctx.set('ETag', '123')
      assert.strictEqual(ctx.fresh, false)
    })
  })

  describe('the response is 2xx', () => {
    describe('and etag matches', () => {
      it('should return true', () => {
        const ctx = context()
        ctx.status = 200
        ctx.req.method = 'GET'
        ctx.req.headers['if-none-match'] = '123'
        ctx.set('ETag', '123')
        assert.strictEqual(ctx.fresh, true)
      })
    })

    describe('and etag does not match', () => {
      it('should return false', () => {
        const ctx = context()
        ctx.status = 200
        ctx.req.method = 'GET'
        ctx.req.headers['if-none-match'] = '123'
        ctx.set('ETag', 'hey')
        assert.strictEqual(ctx.fresh, false)
      })
    })
  })
})