compat-review

Original：🇺🇸 English

Translated

Verify compat PR claims by running lodash vs es-toolkit/compat at runtime

2installs

Sourcetoss/es-toolkit

Added on2026-08-29

NPX Install

npx skill4agent add toss/es-toolkit compat-review

SKILL.md Content

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Compat Layer Review

Verify that a compat PR actually fixes a real lodash inconsistency.

Input

$ARGUMENTS — PR number (e.g.

) or function name (e.g.

chunk

)

Workflow

1. Identify target function and PR claims

PR number:

bash

gh pr view {number} --repo toss/es-toolkit --json title,body,files

From the PR description and diff, extract:

Which compat function is being fixed
What inconsistency the contributor claims (expected vs actual behavior)
Any test examples the contributor provides

Function name: Read the function source and its spec to understand current behavior.

2. Build comparison test

Create a temporary vitest spec at

src/compat/{category}/_compat-review-{fn}.spec.ts

.

typescript

import { describe, expect, it } from 'vitest';
import { fn as compatFn } from 'es-toolkit/compat';
import { fn as lodashFn } from 'lodash';

Include two groups of test cases:

A. Contributor's claimed examples — Extract directly from the PR description or test diff. These are the cases the PR claims to fix.

B. ~10 additional edge cases you generate — Based on the function's signature and lodash's known behavior patterns:

Empty inputs:
```
[]
```
,
```
{}
```
,
```
''
```
,
```
0
```
Nullish:
```
null
```
,
```
undefined
```
Negative/zero/float numbers:
```
-1
```
,
```
0
```
,
```
1.5
```
,
```
NaN
```
,
```
Infinity
```
Type coercion: string numbers (
```
'3'
```
), boolean, mixed types
Boundary: single-element arrays, very long strings, deeply nested objects
Pick cases that are relevant to the specific function

Each test:

typescript

it('description', () => {
  let lodashResult, compatResult;
  let lodashErr: any, compatErr: any;
  try {
    lodashResult = lodashFn(args);
  } catch (e) {
    lodashErr = e;
  }
  try {
    compatResult = compatFn(args);
  } catch (e) {
    compatErr = e;
  }

  if (lodashErr && compatErr) return; // both throw = consistent
  if (lodashErr || compatErr) {
    throw new Error(`Behavior mismatch: ${lodashErr ? 'lodash throws' : 'compat throws'}`);
  }
  expect(compatResult).toEqual(lodashResult);
});

3. Run comparison BEFORE the PR change

bash

yarn vitest run src/compat/{category}/_compat-review-{fn}.spec.ts

Record which tests fail — these are real inconsistencies that exist on main.

4. Apply PR changes and re-run

bash

gh pr diff {number} --repo toss/es-toolkit | git apply

Run the same test again. Confirm that:

The contributor's claimed examples now pass
The additional edge cases still pass (no regressions)

Revert after testing:

bash

git checkout -- .

5. Clean up

Delete

_compat-review-*.spec.ts

.

6. Report

## {fn} — Compat Review

### PR Claim
{What the contributor says they're fixing}

### Verification (BEFORE fix)
| # | Input | lodash | compat | Match? | Source |
|---|-------|--------|--------|--------|--------|
| 1 | ...   | ...    | ...    | MISMATCH | PR example |
| 2 | ...   | ...    | ...    | MATCH    | Edge case |

### Verification (AFTER fix)
| # | Input | lodash | compat | Match? | Source |
|---|-------|--------|--------|--------|--------|

### Verdict
- [ ] PR claim is valid (inconsistency confirmed on main)
- [ ] Fix resolves the claimed inconsistency
- [ ] No regressions in edge cases
- [ ] Existing tests still pass

compat-review

NPX Install

Tags

SKILL.md Content

Compat Layer Review

Input

Workflow

1. Identify target function and PR claims

2. Build comparison test

3. Run comparison BEFORE the PR change

4. Apply PR changes and re-run

5. Clean up

6. Report