E2E Test Creator

What it does

When your agent uses it

• After implementing a new API endpoint
• Tasks that involve End-to-end testing
• Tasks that involve REST APIs

Example prompts

• “/e2e-test-creator”
• “Use the e2e-test-creator skill to create backend e2e tests for new or existing endpoints. An agent skill from letehaha/moneymatter”
• “/e2e-test-creator”

Requirements

• Pre-approved tools (allowed-tools): Read, Write, Edit, Grep, Glob, Bash, AskUserQuestion

Workflow steps

4 steps, taken from the step headings in SKILL.md.

1. 1Gather Context
2. 2Ensure Test Helper Exists
3. 3Write the Test File
4. 4Verify

What it can do on your machine

Read from SKILL.md and the folder at commit de5319f. It shows what the files ask for, not the result of running them.

• Tool permissions

  Pre-approves these tools, so the agent can use them without asking each time:

  • Read
  • Write
  • Edit
  • Grep
  • Glob
  • Bash
  • AskUserQuestion

  From allowed-tools in the SKILL.md frontmatter.

• Runs code

  Shell commands in SKILL.md call:

  • npm

  From the folder's file list and the shell code blocks in SKILL.md.

• Network

  No URLs in SKILL.md. Its commands use npm, which can reach the network depending on how they are called.

  From URLs in SKILL.md, links to its own repository left out.

• Credentials

  Names no API keys, tokens, secrets or passwords.

  From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

E2E Test Creator loads about 2.4k tokens when it runs. Until then it costs about 70 tokens; SKILL.md has 628 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it

~70

When it runs · the whole SKILL.md, loaded when a task matches

~2.4k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

• WarningTells the agent its actions are pre-authorized / not to stop for confirmationSKILL.md:181

  Run from `packages/backend/`. Do NOT wait for user confirmation — run tests immediately after writing them.

• NotePre-approves every shell command (allowed-tools: Bash)SKILL.md

  allowed-tools: Read, Write, Edit, Grep, Glob, Bash, AskUserQuestion

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from letehaha/moneymatter at commit de5319f, republished under its AGPL-3.0 licence (© letehaha). 628 words, ~2,396 tokens.

name

e2e-test-creator

description

Creates backend e2e tests for new or existing endpoints. Auto-triggers after implementing a new API endpoint. Also runs when asked to add test coverage or triggered by "/e2e-test-creator". Follows project conventions for test structure, helpers, and assertions.

allowed-tools

Read, Write, Edit, Grep, Glob, Bash, AskUserQuestion

import type { myService as apiMyService } from '@services/<domain>/my-service';
import { makeRequest } from './common';

export async function myEndpoint<R extends boolean | undefined = undefined>({
  raw,
  // ... endpoint-specific params
}: {
  raw?: R;
  // ... param types
} = {}) {
  return makeRequest<Awaited<ReturnType<typeof apiMyService>>, R>({
    method: 'get', // or post, put, patch, delete
    url: '/<domain>/endpoint',
    raw,
  });
}

import { describe, expect, it } from '@jest/globals';
import * as helpers from '@tests/helpers';
// Import enums/types needed for test data
import { SOME_ENUM } from '@bt/shared/types';

describe('Feature Name', () => {
  // Group by logical concern
  describe('GET /endpoint', () => {
    it('returns expected data for happy path', async () => {
      // ARRANGE: create prerequisite data via helpers
      const account = await helpers.createAccount({ raw: true });

      // ACT: call the endpoint being tested
      const result = await helpers.myEndpoint({ raw: true });

      // ASSERT: verify the response
      expect(result.someField).toBe(expectedValue);
    });

    it('returns empty/default when no data exists', async () => {
      const result = await helpers.myEndpoint({ raw: true });
      expect(result.count).toBe(0);
    });

    it('filters by query parameter', async () => {
      // Create mixed data
      await helpers.createThing({ type: 'a', raw: true });
      await helpers.createThing({ type: 'b', raw: true });

      // Filter
      const result = await helpers.myEndpoint({ type: 'a', raw: true });
      expect(result.length).toBe(1);
    });
  });
});

// WRONG
const result = await getSubscriptionsSummary({ userId: 1 });

// CORRECT
const result = await helpers.getSubscriptionsSummary({ raw: true });

// Happy path — get extracted data directly
const data = await helpers.getSomething({ raw: true });
expect(data.name).toBe('expected');

// Error case — check HTTP status code
const res = await helpers.getSomething({ id: 'nonexistent' });
expect(res.statusCode).toBe(404);

npm run test:e2e -- --testPathPattern='<pattern>'

import { SUBSCRIPTION_FREQUENCIES, SUBSCRIPTION_TYPES } from '@bt/shared/types';
import { describe, expect, it } from '@jest/globals';
import * as helpers from '@tests/helpers';

describe('Subscriptions Summary', () => {
  describe('GET /subscriptions/summary', () => {
    it('returns summary with correct monthly cost', async () => {
      await helpers.createSubscription({
        name: 'Netflix',
        expectedAmount: 1500,
        expectedCurrencyCode: global.BASE_CURRENCY_CODE,
        frequency: SUBSCRIPTION_FREQUENCIES.monthly,
        startDate: '2025-01-01',
        raw: true,
      });

      const summary = await helpers.getSubscriptionsSummary({ raw: true });

      expect(summary.activeCount).toBe(1);
      expect(summary.estimatedMonthlyCost).toBe(15);
      expect(summary.projectedYearlyCost).toBe(180);
      expect(summary.currencyCode).toBe(global.BASE_CURRENCY_CODE);
    });

    it('returns zeros when no active subscriptions exist', async () => {
      const summary = await helpers.getSubscriptionsSummary({ raw: true });

      expect(summary.activeCount).toBe(0);
      expect(summary.estimatedMonthlyCost).toBe(0);
      expect(summary.projectedYearlyCost).toBe(0);
    });

    it('filters by subscription type', async () => {
      await helpers.createSubscription({
        name: 'Netflix',
        type: SUBSCRIPTION_TYPES.subscription,
        expectedAmount: 1500,
        expectedCurrencyCode: global.BASE_CURRENCY_CODE,
        frequency: SUBSCRIPTION_FREQUENCIES.monthly,
        startDate: '2025-01-01',
        raw: true,
      });
      await helpers.createSubscription({
        name: 'Electricity',
        type: SUBSCRIPTION_TYPES.bill,
        expectedAmount: 10000,
        expectedCurrencyCode: global.BASE_CURRENCY_CODE,
        frequency: SUBSCRIPTION_FREQUENCIES.monthly,
        startDate: '2025-01-01',
        raw: true,
      });

      const subsOnly = await helpers.getSubscriptionsSummary({
        type: SUBSCRIPTION_TYPES.subscription,
        raw: true,
      });
      expect(subsOnly.activeCount).toBe(1);
      expect(subsOnly.estimatedMonthlyCost).toBe(15);

      const billsOnly = await helpers.getSubscriptionsSummary({
        type: SUBSCRIPTION_TYPES.bill,
        raw: true,
      });
      expect(billsOnly.activeCount).toBe(1);
      expect(billsOnly.estimatedMonthlyCost).toBe(100);
    });
  });
});

© letehaha, AGPL-3.0. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

Just SKILL.md in .claude/skills/e2e-test-creator of letehaha/moneymatter.

Open the folder on GitHubat commit de5319f