TESTING

Test Writer

Writes targeted unit and integration tests that cover real edge cases instead of padding a coverage number.

SIMURAI Verifiedv4.0.2Claude · Codex · Cursor

Install Skill View Source

What It Does

Identifies edge cases from the implementation, not just the happy path
Matches the project's existing test framework and style automatically
Writes readable test names that describe behavior, not implementation
Avoids brittle tests coupled to internal implementation details
Flags untestable code and suggests a minimal refactor to unlock it

When To Use It

Backfilling tests for an untested legacy module
Writing tests alongside a new feature before merge
Covering a bug with a regression test before fixing it
Auditing test suite gaps around a risky function

When Not To Use It

Does not write end-to-end browser tests out of the box
Coverage suggestions require the project's test runner already configured

How It Works

Read the implementation and its existing test file, if any
Enumerate boundary conditions: empty, null, max, concurrent, error paths
Write tests using the project's existing framework and assertion style
Run the suite locally and fix any failing assumption
Report coverage delta and any code that remains untestable

See It In Action

Before & After

Before

function divide(a: number, b: number) {
  return a / b;
}
// no tests exist

SIMURAI Analysis

divide() has no tests and two silent edge cases: division by zero returns Infinity instead of throwing, and 0/0 returns NaN — both easy to miss until production.

Cover the zero-divisor boundary explicitly so future refactors can't silently change this behavior without a failing test.

After

describe("divide", () => {
  it("divides two positive numbers", () => {
    expect(divide(10, 2)).toBe(5);
  });
  it("returns Infinity when dividing by zero", () => {
    expect(divide(5, 0)).toBe(Infinity);
  });
  it("returns NaN for 0/0", () => {
    expect(divide(0, 0)).toBeNaN();
  });
});

Installation

Install This Skill

npx simurai install test-writer --client claude

Skill Contents

What's Inside

File Tree

test-writer/
  SKILL.md
  references/
    edge-case-checklist.md
    framework-detection.md

SKILL.md preview

---
name: test-writer
description: Targeted unit and integration tests covering real edge cases.
---

# Test Writer

Enumerate boundary conditions before writing a single assertion:
empty, null, max, concurrent, error paths. Match the project's
existing framework. A test name should describe behavior.

View SKILL.md View Source

Mastery

93/ 100

Precision94

Coverage95

Reliability90

Maintainability91

History