feat: typescript plugin poc implementation

[BioPhoton]

TypeScript Plugin PoC Implementation

Incremental migration for TypeScript projects
This plugin enables step-by-step adoption of newer TypeScript features while avoiding large-scale refactors.

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📝 Related Issue

👉 #901 – TypeScript Plugin Architecture Discussion

NOTE:
This PoC PR serves as an initial implementation to validate the proposed architecture and core functionality.
The final implementation will be delivered in smaller, focused PRs to ensure clarity, better reviewability, and incremental improvements.

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🔌 Plugin Overview

Purpose

The plugin enables incremental adoption of TypeScript configurations and helps track regressions while avoiding CI failures.

Key Features:

✅ Extracts Diagnostics: Uses TypeScript’s compiler APIs to analyze diagnostics.
✅ Audit Mapping: Maps diagnostics to audit rules for actionable feedback.
✅ Migration Support: Handles migration via separate configs (tsconfig.json, tsconfig.next.json).
✅ Detailed Reports: Provides grouped, actionable error/warning summaries.

Report Summary

Overview of Audit Groups, Audit Counts, and Diagnostic Issue Types.
TypeScript's own guidelines on diagnostic code ranges

🗂 Group Name	📋 Audits	🐞 Issues
Problems Group (3)	syntax-errors, semantic-errors, internal-errors, no-implicit-any	1XXX, 2XXX, 5XXX , 7XXX
Suggestions Group (1)	suggestions	3XXX [1]
Configuration Group (1)	configuration-errors	6XXX
Ungrouped Audits (2).	language-service-errors, unknown-codes	4XXX.
----------------------------	------------------------------------------------------------------------	-----------------------------
3 Groups Total	6 Audits Total	5 Ranges Total

• [1] - Suggestions Group (3XXX range) is included for completeness but is better handled by the ESLint Plugin and CodePushup's @code-pushup/eslint-config.

This PR includes:

• implementation
• unit tests
• integration tests
  • diagnostics generation
  • runner execution
• e2e tests
  • report generation

Proposed PR delivery:

• changes in @code-pushup/utils - feat(utils): add string helper #916
• plugin base - feat(plugin-typescript): setup plugin project base #917
• runner logic - feat(plugin-typescript): add TS core logic #932
• plugin utils - feat(plugin-typescript): add plugin logic #936
• e2e & CONTRIBUTING.md - test(plugin-typescript-e2e): add basic e2e tests #974
• plugin & usage
• docs

⚠️ Limitations & Challenges

• Range Mapping: No direct link between diagnostics and compiler options; requires manual grouping in within ranges to get more fine-grained audits.

Alternatives

• reimplemented compiler option to as audit mapping: Big effort and hard to maintain.
• TS-code as audit: A audit per TS-code e.g. ts-2345 .
  This leads to a huge amount of audits > ~2000 if not reduces to a subset of useful codes, hard to understand audit slug
• A reduced set of supported Audits: A subset of manually maintained audits and related logic for defaults like in the implemented version of this PR.
• Patching TypeScript: Patching TypeScript to expose the internal logic. - fragile and unreliable

🧪 How to Test the Plugin

1. run nx code-pushup --onlyPlugins=typescript to execute the plugin and generate the report
2. the generated report is available under .code-pushup/report.md

📊 Visual Examples

🖥️ Dashboard Overview
Central view showing audit results and issue summaries.

📂 Additional Visuals

Click below to explore more detailed visuals.

📸 Expand to View More Visuals

🖥️ Audit Insights 1
Drill-down view for grouped audits and diagnostics.

🖥️ Audit Insights 2
Deeper inspection of diagnostics linked to audits.

🛠️ Code Diagnostics 1
Pinpoint file locations and error lines.

🛠️ Code Diagnostics 2
Detailed breakdown of warnings and errors.

Example Md Report:

Code PushUp Report

🏷 Category	⭐ Score	🛡 Audits
Typescript Configuration	🟡 85	6
Bug prevention	🟡 78	5
Code style	🟢 100	2

🏷 Categories

Typescript

🟡 Score: 85

• 🟡 Problems (Typescript)
  • 🟥 Semantic-Errors - 5
  • 🟩 Internal-Errors - 0
  • 🟡 Syntax-Errors - 2
• 🟢 Configuration (Typescript)
  • 🟩 Configuration-Errors - 0

🛡️ Audits

Semantic-Errors (Typescript)

🟥 19 (score: 0)

Issues

Severity	Message	Source file	Line(s)
🚨 error	TS2307: Cannot find module './non-existent' or its corresponding type declarations.	src/module-resolution/ts-2307-module-not-fount.ts	2
🚨 error	TS2683: 'this' implicitly has type 'any' because it does not have a type annotation.	src/strict/no-implicit-this/ts-2683-not-implicit-this.ts	3
🚨 error	TS2349: This expression is not callable. Type 'Number' has no call signatures.	src/strict/strict-function-types/ts-2349-not-callable.ts	3
🚨 error	TS2322: Type 'null' is not assignable to type 'string'.	src/strict/strict-null-checks/ts-2531-strict-null-checks.ts	2
🚨 error	TS2367: Condition will always return 'false' since types have no overlap.	src/strict/conditional-types/ts-2367-invalid-condition.ts	4

📖 Docs

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closes #901

[github-actions]

Code PushUp

🤨 Code PushUp report has both improvements and regressions – compared target commit 97d1de7 with source commit c219602.

🕵️ See full comparison in Code PushUp portal 🔍

🏷️ Categories

🏷️ Category	⭐ Previous score	⭐ Current score	🔄 Score change
Performance	🟡 58	🟡 54
Code coverage	🟢 91	🟢 91
Typescript	n/a (*)	🟢 91	n/a (*)
Security	🟡 81	🟡 81	–
Updates	🟡 80	🟡 80	–
Accessibility	🟢 91	🟢 91	–
Best Practices	🟢 100	🟢 100	–
SEO	🟡 61	🟡 61	–
Bug prevention	🟢 100	🟢 100	–
Code style	🟢 100	🟢 100	–

(*) New category.

👎 2 groups regressed, 👍 1 audit improved, 👎 6 audits regressed, 11 audits changed without impacting score

🗃️ Groups

🔌 Plugin	🗃️ Group	⭐ Previous score	⭐ Current score	🔄 Score change
Lighthouse	Performance	🟡 58	🟡 54
Code coverage	Code coverage metrics	🟢 91	🟢 91

15 other groups are unchanged.

🛡️ Audits

🔌 Plugin	🛡️ Audit	📏 Previous value	📏 Current value	🔄 Value change
Lighthouse	Largest Contentful Paint	🟨 2.9 s	🟨 3.3 s
Lighthouse	Speed Index	🟨 4.7 s	🟨 5.3 s
Lighthouse	First Contentful Paint	🟨 2.7 s	🟨 2.7 s
Lighthouse	Total Blocking Time	🟥 3,750 ms	🟥 3,190 ms
Code coverage	Line coverage	🟩 90.9 %	🟩 90.2 %
Code coverage	Branch coverage	🟨 85.8 %	🟨 85.5 %
Code coverage	Function coverage	🟩 93.1 %	🟩 93.1 %
Lighthouse	Avoids enormous network payloads	🟩 Total size was 1,816 KiB	🟩 Total size was 1,821 KiB
Lighthouse	Max Potential First Input Delay	🟥 2,270 ms	🟥 1,760 ms
Lighthouse	Minimizes main-thread work	🟥 13.9 s	🟥 13.5 s
Lighthouse	Uses efficient cache policy on static assets	🟨 28 resources found	🟨 28 resources found
Lighthouse	JavaScript execution time	🟥 6.1 s	🟥 6.3 s
Lighthouse	Eliminate render-blocking resources	🟥 Potential savings of 970 ms	🟥 Potential savings of 770 ms
Lighthouse	Time to Interactive	🟥 13.0 s	🟥 13.2 s
Lighthouse	Metrics	🟩 100%	🟩 100%
Lighthouse	Initial server response time was short	🟩 Root document took 430 ms	🟩 Root document took 350 ms
Lighthouse	Server Backend Latencies	🟩 100 ms	🟩 60 ms
Lighthouse	Network Round Trip Times	🟩 10 ms	🟩 20 ms

569 other audits are unchanged.

[matejchalk]

Exciting stuff 🚀

[BioPhoton]

Closed as implemented