feat(definePlugin): helper function to create plugins

[chimurai]

Summary by CodeRabbit

• New Features

  • Added a definePlugin helper to simplify creating custom plugins with improved TypeScript support

• Documentation

  • Added README guide and examples showing how to create and register custom plugins

• Chores

  • Added a top-level "next" changelog section and updated the changelog

• Refactor

  • Consolidated plugin exports behind a single plugins entry point and updated library exports to use it

• Tests

  • Updated type, unit and e2e tests to exercise and validate the new definePlugin helper

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: f5192093-054d-4603-a1cb-6946f1841fc4

📥 Commits

Reviewing files that changed from the base of the PR and between dc340f2 and 697d14c.

📒 Files selected for processing (1)

• README.md

✅ Files skipped from review due to trivial changes (1)

• README.md

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📝 Walkthrough

Walkthrough

This PR adds a generic definePlugin helper, re-exports it via a consolidated src/plugins entrypoint, refactors the four default plugins to use definePlugin, and updates README, CHANGELOG, type/unit/e2e tests to use and document the helper.

Changes

definePlugin Helper Introduction

Layer / File(s)	Summary
Plugin Helper Type Definition src/plugins/define-plugin.ts	New module exports definePlugin, a generic function parameterized over request/response types, returning the passed Plugin unchanged.
Public API Export src/plugins/index.ts, src/index.ts	Adds a src/plugins entrypoint that re-exports define-plugin and default plugins; package entrypoint now re-exports from ./plugins/index.js.
Default Plugins Refactored src/plugins/default/debug-proxy-errors-plugin.ts, src/plugins/default/error-response-plugin.ts, src/plugins/default/logger-plugin.ts, src/plugins/default/proxy-events.ts	All default plugins are wrapped with definePlugin(...), changing exported initialization syntax while preserving internal handler logic; logger-plugin also relaxes an explicit request param typing in a handler.
Tests and Documentation CHANGELOG.md, README.md, test/types.spec.ts, test/unit/get-plugins.spec.ts, test/e2e/plugins.spec.ts	Changelog records feature. README TOC and new "definePlugin helper" section with TS example. Type tests add definePlugin() typing checks; unit/e2e tests updated to import/use definePlugin and switch some assertions to structural equality.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~12 minutes

Possibly related PRs

• chimurai/http-proxy-middleware#1215: Also modifies logger-plugin.ts; that PR changes URL construction and IPv6/protocol handling while this PR wraps the logger with definePlugin and updates parameter typing.
• chimurai/http-proxy-middleware#1195: Related edits under src/plugins/default and changes to plugin typing/imports; both touch plugin modules and type-only import patterns.

Poem

🐰 I shape plugins with gentle paws and cheer,
definePlugin whispers types so clear,
Four old friends wrapped in a typed embrace,
Docs and tests confirm each place,
Hooray — plugins now hop with grace!

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 33.33% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The pull request title accurately describes the main change: introducing a new definePlugin helper function for creating plugins.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch define-plugin

---

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[pkg-pr-new]

npm i https://pkg.pr.new/http-proxy-middleware@1229

commit: 697d14c

[coveralls]

coverage: 94.086% (+0.02%) from 94.07% — define-plugin into master

[coderabbitai]

Actionable comments posted: 1

🧹 Nitpick comments (1)

test/unit/get-plugins.spec.ts (1)

10-10: ⚡ Quick win

Prefer importing definePlugin from the public entrypoint in this test.

Using ../../src/index.js here keeps the test aligned with public API usage and avoids coupling to internal module paths.

Suggested change

 import {
   debugProxyErrorsPlugin,
+  definePlugin,
   errorResponsePlugin,
   loggerPlugin,
   proxyEventsPlugin,
 } from '../../src/index.js';
-import { definePlugin } from '../../src/plugins/define-plugin.js';

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@test/unit/get-plugins.spec.ts` at line 10, The test imports definePlugin
directly from an internal module; change the import in
test/unit/get-plugins.spec.ts to pull definePlugin from the public entrypoint
(the package's main export, e.g. '../../src/index.js') instead of
'../../src/plugins/define-plugin.js' so the test uses the public API; keep the
named import (definePlugin) the same and update only the module path.

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@README.md`:
- Around line 305-314: The example is missing imports for definePlugin and
createProxyMiddleware; update the snippet to explicitly import these symbols
(e.g., add an import that includes definePlugin and createProxyMiddleware from
the library) so readers can copy/paste and run the definePlugin(...) and
createProxyMiddleware(...) example without errors.

---

Nitpick comments:
In `@test/unit/get-plugins.spec.ts`:
- Line 10: The test imports definePlugin directly from an internal module;
change the import in test/unit/get-plugins.spec.ts to pull definePlugin from the
public entrypoint (the package's main export, e.g. '../../src/index.js') instead
of '../../src/plugins/define-plugin.js' so the test uses the public API; keep
the named import (definePlugin) the same and update only the module path.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: bdf84f0d-3172-4762-9f00-397275ec0fa9

📥 Commits

Reviewing files that changed from the base of the PR and between ba9f262 and e69397a.

📒 Files selected for processing (10)

• CHANGELOG.md
• README.md
• src/index.ts
• src/plugins/default/debug-proxy-errors-plugin.ts
• src/plugins/default/error-response-plugin.ts
• src/plugins/default/logger-plugin.ts
• src/plugins/default/proxy-events.ts
• src/plugins/define-plugin.ts
• test/types.spec.ts
• test/unit/get-plugins.spec.ts