config-audit/tests/scanners/subtraction-write-cli.test.mjs

/**
 * subtraction-write CLI — the exit-code contract and the payload the command
 * template acts on (#63).
 *
 * The contract worth defending here is the one #62 settled: a gated write is a
 * VERDICT, not a tool failure. Exit 3 means the CLI could not do its job; "this
 * removal would touch your machine-wide config, approve it first" is an answer,
 * and it has to arrive in the payload — a command that runs everything as
 * `--output-file <path> 2>/dev/null` cannot act on anything that only reached
 * stderr.
 */

import { describe, it, beforeEach, afterEach } from 'node:test';
import assert from 'node:assert/strict';
import { join, resolve, dirname } from 'node:path';
import { mkdtemp, readFile, writeFile, rm, mkdir } from 'node:fs/promises';
import { tmpdir } from 'node:os';
import { spawn } from 'node:child_process';
import { fileURLToPath } from 'node:url';

const __dirname = dirname(fileURLToPath(import.meta.url));
const CLI = resolve(__dirname, '..', '..', 'scanners', 'subtraction-write-cli.mjs');

const BLOCK_A = '- Always write tests before code, and never skip the failing step.';
const FIXTURE = ['# Project', '', '## Rules', '', BLOCK_A, '', '## End', ''].join('\n');

let dir;
let repo;
let file;
let approvedPath;
let outPath;
let env;

/** Run the CLI with a home and backup root that are never the operator's. */
function run(argv) {
  return new Promise((res) => {
    const child = spawn(process.execPath, [CLI, ...argv], { cwd: repo, env });
    let stderr = '';
    let stdout = '';
    child.stderr.on('data', (d) => { stderr += d; });
    child.stdout.on('data', (d) => { stdout += d; });
    child.on('close', (code) => res({ code, stdout, stderr }));
  });
}

beforeEach(async () => {
  dir = await mkdtemp(join(tmpdir(), 'config-audit-subwrite-cli-'));
  repo = join(dir, 'repo');
  await mkdir(join(repo, '.git'), { recursive: true });
  file = join(repo, 'CLAUDE.md');
  await writeFile(file, FIXTURE, 'utf-8');

  approvedPath = join(dir, 'approved.json');
  outPath = join(dir, 'result.json');
  env = {
    ...process.env,
    HOME: join(dir, 'home'),
    CONFIG_AUDIT_BACKUP_ROOT: join(dir, 'backups'),
  };
  await mkdir(join(dir, 'home', '.claude'), { recursive: true });
});

afterEach(async () => {
  await rm(dir, { recursive: true, force: true });
});

async function writeApproval(removals) {
  await writeFile(approvedPath, JSON.stringify({ sessionId: 'test', removals }), 'utf-8');
}

describe('subtraction-write-cli', () => {
  it('applies an approved removal and reports it in the payload', async () => {
    await writeApproval([{ file, line: 5, endLine: 5, text: BLOCK_A }]);
    const { code } = await run(['--approved', approvedPath, '--repo', repo, '--output-file', outPath]);

    assert.equal(code, 0);
    const payload = JSON.parse(await readFile(outPath, 'utf-8'));
    assert.equal(payload.counts.applied, 1);
    assert.equal(payload.counts.filesWritten, 1);
    assert.ok(payload.backupId, 'a verified backup must precede the write');
    assert.equal(payload.applied[0].text, BLOCK_A, 'the receipt carries what left the file');
    assert.ok(!(await readFile(file, 'utf-8')).includes(BLOCK_A));
  });

  it('gates a machine-wide target with exit 0 and a disclosure, writing nothing', async () => {
    const userFile = join(dir, 'home', '.claude', 'CLAUDE.md');
    await writeFile(userFile, FIXTURE, 'utf-8');
    await writeApproval([{ file: userFile, line: 5, endLine: 5, text: BLOCK_A }]);

    const { code } = await run(['--approved', approvedPath, '--repo', repo, '--output-file', outPath]);

    assert.equal(code, 0, 'a gated write is a verdict about a write, never exit 3 (#62)');
    const payload = JSON.parse(await readFile(outPath, 'utf-8'));
    assert.equal(payload.gate, 'require-ok');
    assert.equal(payload.requiresApproval, true);
    assert.ok(
      payload.disclosures.some((d) => /machine-wide/i.test(d)),
      'the payload must carry WHY, not just that it refused',
    );
    assert.equal(payload.counts.applied, 0);
    assert.equal(payload.counts.filesWritten, 0);
    assert.equal(await readFile(userFile, 'utf-8'), FIXTURE);
  });

  it('proceeds on that same target with --approve-scope', async () => {
    const userFile = join(dir, 'home', '.claude', 'CLAUDE.md');
    await writeFile(userFile, FIXTURE, 'utf-8');
    await writeApproval([{ file: userFile, line: 5, endLine: 5, text: BLOCK_A }]);

    const { code } = await run([
      '--approved', approvedPath, '--repo', repo, '--approve-scope', '--output-file', outPath,
    ]);

    assert.equal(code, 0);
    const payload = JSON.parse(await readFile(outPath, 'utf-8'));
    assert.equal(payload.counts.applied, 1);
    assert.ok(!(await readFile(userFile, 'utf-8')).includes(BLOCK_A));
  });

  it('--dry-run reports the removal and leaves the file alone', async () => {
    await writeApproval([{ file, line: 5, endLine: 5, text: BLOCK_A }]);
    const { code } = await run([
      '--approved', approvedPath, '--repo', repo, '--dry-run', '--output-file', outPath,
    ]);

    assert.equal(code, 0);
    const payload = JSON.parse(await readFile(outPath, 'utf-8'));
    assert.equal(payload.meta.dryRun, true);
    assert.equal(payload.counts.applied, 1);
    assert.equal(payload.counts.filesWritten, 0);
    assert.equal(payload.backupId, null);
    assert.equal(await readFile(file, 'utf-8'), FIXTURE);
  });

  it('a stale approval is refused in the payload, not as a tool error', async () => {
    await writeApproval([{ file, line: 5, endLine: 5, text: '- A block that is not there.' }]);
    const { code } = await run(['--approved', approvedPath, '--repo', repo, '--output-file', outPath]);

    assert.equal(code, 0);
    const payload = JSON.parse(await readFile(outPath, 'utf-8'));
    assert.equal(payload.counts.applied, 0);
    assert.equal(payload.refused[0].reason, 'block-mismatch');
    assert.equal(await readFile(file, 'utf-8'), FIXTURE);
  });

  it('exits 3 without --approved', async () => {
    const { code, stderr } = await run(['--repo', repo]);
    assert.equal(code, 3);
    assert.match(stderr, /--approved/);
  });

  it('exits 3 on an approval file with no removals — an empty set is not "all done"', async () => {
    await writeFile(approvedPath, JSON.stringify({ removals: [] }), 'utf-8');
    const { code, stderr } = await run(['--approved', approvedPath, '--repo', repo]);
    assert.equal(code, 3);
    assert.match(stderr, /removals/);
  });

  it('exits 3 on a removal missing its text — an unverifiable approval is not a licence to delete', async () => {
    await writeApproval([{ file, line: 5, endLine: 5 }]);
    const { code, stderr } = await run(['--approved', approvedPath, '--repo', repo]);
    assert.equal(code, 3);
    assert.match(stderr, /text/);
    assert.equal(await readFile(file, 'utf-8'), FIXTURE);
  });
});