feat: support JSON and JSONC config files

README.md

@@ -17,6 +17,10 @@ Enjoying **Poku**? [Give him a star to show your support](https://github.com/wel
 
 ☔️ [**@pokujs/c8**](https://github.com/pokujs/c8) is a **Poku** plugin for **V8** code coverage using [**c8**](https://github.com/bcoe/c8).
 
+> [!TIP]
+>
+> **@pokujs/c8** supports **JSONC** config files (`.c8rc`, `.nycrc`, etc.) out of the box, allowing comments in your configuration. You can also use **JS** and **TS** by setting the options directly in the plugin.
+
 ---
 
 ## Quickstart
@@ -53,10 +57,13 @@ Run `poku` and a coverage summary will be printed after your test results.
 
 ```js
 coverage({
+  // Config file (.c8rc, .c8rc.json, .c8rc.jsonc, .nycrc, .nycrc.json, .nycrc.jsonc)
+  config: '.c8rc', // default: auto-discover
+
   // Activation
   requireFlag: true, // default: false
 
-  // Reporters
+  // Reporters (clover, cobertura, html, html-spa, json, json-summary, lcov, lcovonly, none, teamcity, text, text-lcov, text-summary)
   reporter: ['text', 'lcov'], // default: ['text']
 
   // File selection
@@ -165,6 +172,42 @@ poku test/
 poku --coverage test/
 ```
 
+### Using a config file
+
+Reuse your existing `.c8rc`, `.nycrc`, or any JSON/JSONC config file with comments:
+
+```jsonc
+// .c8rc
+{
+  // Only cover source files
+  "include": ["src/**"],
+  "reporter": ["text", "lcov"],
+  "check-coverage": true,
+  "lines": 90,
+}
+```
+
+```js
+coverage({
+  config: '.c8rc', // or false to disable auto-discovery
+});
+```
+
+When no `config` is specified, the plugin automatically searches for `.c8rc`, `.c8rc.json`, `.c8rc.jsonc`, `.nycrc`, `.nycrc.json`, or `.nycrc.jsonc` in the working directory.
+
+You can also specify the config path via CLI:
+
+```bash
+poku --coverage-config=.c8rc test/
+```
+
+> [!NOTE]
+>
+> **Priority order:**
+>
+> - For config file discovery: `--coverage-config` (CLI) > `config` (plugin option) > auto-discovery
+> - For coverage options: plugin options > config file options
+
 ### Extending Monocart reporters
 
 ```bash

package.json

@@ -25,6 +25,7 @@
     "node": ">=18.x.x"
   },
   "scripts": {
+    "pretest": "npm run build",
     "test": "poku test/e2e",
     "prebuild": "rm -rf lib",
     "build": "tsc",
@@ -34,7 +35,8 @@
     "postupdate": "npm run lint:fix"
   },
   "dependencies": {
-    "c8": "^10.1.3"
+    "c8": "^10.1.3",
+    "jsonc.min": "^1.1.2"
   },
   "peerDependencies": {
     "monocart-coverage-reports": "^2.12.9",

src/config.ts

@@ -0,0 +1,61 @@
+import type { CoverageOptions } from './types.js';
+import { existsSync, readFileSync } from 'node:fs';
+import { join } from 'node:path';
+import { JSONC } from 'jsonc.min';
+
+const kebabMap: Record<string, string> = {
+  'reports-dir': 'reportsDirectory',
+  'report-dir': 'reportsDirectory',
+  'temp-directory': 'tempDirectory',
+  'check-coverage': 'checkCoverage',
+  'per-file': 'perFile',
+  'skip-full': 'skipFull',
+  'exclude-after-remap': 'excludeAfterRemap',
+  'merge-async': 'mergeAsync',
+};
+
+const mapKeys = (raw: Record<string, unknown>): Partial<CoverageOptions> => {
+  const result: Record<string, unknown> = {};
+
+  for (const [key, value] of Object.entries(raw)) {
+    if (key === 'experimental-monocart') {
+      if (value) result.experimental = ['monocart'];
+      continue;
+    }
+    result[kebabMap[key] ?? key] = value;
+  }
+
+  return result as Partial<CoverageOptions>;
+};
+
+export const loadConfig = (
+  cwd: string,
+  customPath?: string | false
+): CoverageOptions => {
+  if (customPath === false) return Object.create(null);
+
+  const expectedFiles = customPath
+    ? [customPath]
+    : [
+        '.c8rc',
+        '.c8rc.json',
+        '.c8rc.jsonc',
+        '.nycrc',
+        '.nycrc.json',
+        '.nycrc.jsonc',
+      ];
+
+  for (const file of expectedFiles) {
+    const filePath = join(cwd, file);
+
+    if (!existsSync(filePath)) continue;
+
+    try {
+      const content = readFileSync(filePath, 'utf8');
+
+      return mapKeys(JSONC.parse(content) as Record<string, unknown>);
+    } catch {}
+  }
+
+  return Object.create(null);
+};

src/index.ts

@@ -4,6 +4,7 @@ import { mkdirSync, mkdtempSync, rmSync } from 'node:fs';
 import { tmpdir } from 'node:os';
 import { join, resolve } from 'node:path';
 import process from 'node:process';
+import { loadConfig } from './config.js';
 
 export type { CoverageOptions } from './types.js';
 
@@ -22,6 +23,13 @@ export const coverage = (
       if (options.requireFlag && !process.argv.includes('--coverage')) return;
       enabled = true;
 
+      const cliConfig = process.argv
+        .find((arg) => arg.startsWith('--coverage-config'))
+        ?.split('=')[1];
+
+      const fileConfig = loadConfig(context.cwd, cliConfig ?? options.config);
+      options = { ...fileConfig, ...options };
+
       if (context.runtime !== 'node')
         console.warn(
           `[@pokujs/c8] V8 coverage is only supported on Node.js (current runtime: ${context.runtime}). Coverage data may not be collected.`

src/types.ts

@@ -31,6 +31,16 @@ type KnownExtension =
 type Extension = KnownExtension | (string & NonNullable<unknown>);
 
 export type CoverageOptions = {
+  /**
+   * Path to a JSONC/JSON configuration file.
+   *
+   * - `string` — load that specific file
+   * - `false` — disable config file discovery
+   * - `undefined` (default) — auto-discover `.c8rc`, `.c8rc.json`, `.nycrc`, `.nycrc.json`,
+   *   or a `c8` key in `package.json`, walking up from `cwd`.
+   */
+  config?: string | false;
+
   /**
    * Require the `--coverage` CLI flag to activate coverage collection.
    *

test/__fixtures__/e2e/configs/.c8rc

@@ -0,0 +1,5 @@
+{
+  // JSONC: comments should be supported
+  "include": ["src/**"],
+  "reporter": ["text"]
+}

test/__fixtures__/e2e/configs/basic.config.js

@@ -0,0 +1,12 @@
+const { coverage } = require('../../../../lib/index.js');
+
+/** @type {import('poku').PokuConfig} */
+module.exports = {
+  include: ['test/'],
+  plugins: [
+    coverage({
+      include: ['src/**'],
+      reporter: ['text'],
+    }),
+  ],
+};

test/__fixtures__/e2e/configs/config-file.config.js

@@ -0,0 +1,11 @@
+const { coverage } = require('../../../../lib/index.js');
+
+/** @type {import('poku').PokuConfig} */
+module.exports = {
+  include: ['test/'],
+  plugins: [
+    coverage({
+      config: 'configs/.c8rc',
+    }),
+  ],
+};

test/__fixtures__/e2e/configs/require-flag.config.ts → test/__fixtures__/e2e/configs/require-flag.config.js

@@ -1,7 +1,7 @@
-import { defineConfig } from 'poku';
-import { coverage } from '../../../../src/index.ts';
+const { coverage } = require('../../../../lib/index.js');
 
-export default defineConfig({
+/** @type {import('poku').PokuConfig} */
+module.exports = {
   include: ['test/'],
   plugins: [
     coverage({
@@ -10,4 +10,4 @@ export default defineConfig({
       requireFlag: true,
     }),
   ],
-});
+};

test/__fixtures__/e2e/configs/thresholds-fail.config.ts → test/__fixtures__/e2e/configs/thresholds-fail.config.js

@@ -1,7 +1,7 @@
-import { defineConfig } from 'poku';
-import { coverage } from '../../../../src/index.ts';
+const { coverage } = require('../../../../lib/index.js');
 
-export default defineConfig({
+/** @type {import('poku').PokuConfig} */
+module.exports = {
   include: ['test/'],
   plugins: [
     coverage({
@@ -10,4 +10,4 @@ export default defineConfig({
       checkCoverage: 100,
     }),
   ],
-});
+};

test/__fixtures__/e2e/configs/thresholds-pass.config.ts → test/__fixtures__/e2e/configs/thresholds-pass.config.js

@@ -1,7 +1,7 @@
-import { defineConfig } from 'poku';
-import { coverage } from '../../../../src/index.ts';
+const { coverage } = require('../../../../lib/index.js');
 
-export default defineConfig({
+/** @type {import('poku').PokuConfig} */
+module.exports = {
   include: ['test/'],
   plugins: [
     coverage({
@@ -11,4 +11,4 @@ export default defineConfig({
       lines: 30,
     }),
   ],
-});
+};

test/e2e/coverage-basic.test.ts

@@ -6,7 +6,7 @@ const pokuBin = 'node_modules/poku/lib/bin/index.js';
 
 test('basic coverage report is generated', async () => {
   const result = await inspectPoku({
-    command: '-c=configs/basic.config.ts',
+    command: '-c=configs/basic.config.js',
     spawnOptions: { cwd: fixtureDir },
     bin: pokuBin,
   });

test/e2e/coverage-config-file.test.ts

@@ -0,0 +1,17 @@
+import { assert, test } from 'poku';
+import { inspectPoku } from 'poku/plugins';
+
+const fixtureDir = 'test/__fixtures__/e2e';
+const pokuBin = 'node_modules/poku/lib/bin/index.js';
+
+test('loads JSONC config file with comments', async () => {
+  const result = await inspectPoku({
+    command: '-c=configs/config-file.config.js',
+    spawnOptions: { cwd: fixtureDir },
+    bin: pokuBin,
+  });
+
+  assert.strictEqual(result.exitCode, 0);
+  assert(result.stdout.includes('math.ts'));
+  assert(result.stdout.includes('%'));
+});

test/e2e/coverage-require-flag.test.ts

@@ -6,7 +6,7 @@ const pokuBin = 'node_modules/poku/lib/bin/index.js';
 
 test('coverage is skipped without --coverage flag when requireFlag is true', async () => {
   const result = await inspectPoku({
-    command: '-c=configs/require-flag.config.ts',
+    command: '-c=configs/require-flag.config.js',
     spawnOptions: { cwd: fixtureDir },
     bin: pokuBin,
   });
@@ -20,7 +20,7 @@ test('coverage is skipped without --coverage flag when requireFlag is true', asy
 
 test('coverage runs with --coverage flag when requireFlag is true', async () => {
   const result = await inspectPoku({
-    command: '--coverage -c=configs/require-flag.config.ts',
+    command: '--coverage -c=configs/require-flag.config.js',
     spawnOptions: { cwd: fixtureDir },
     bin: pokuBin,
   });

test/e2e/coverage-thresholds.test.ts

@@ -6,7 +6,7 @@ const pokuBin = 'node_modules/poku/lib/bin/index.js';
 
 test('threshold check passes with low threshold', async () => {
   const result = await inspectPoku({
-    command: '-c=configs/thresholds-pass.config.ts',
+    command: '-c=configs/thresholds-pass.config.js',
     spawnOptions: { cwd: fixtureDir },
     bin: pokuBin,
   });
@@ -16,7 +16,7 @@ test('threshold check passes with low threshold', async () => {
 
 test('threshold check fails with 100% threshold on partial coverage', async () => {
   const result = await inspectPoku({
-    command: '-c=configs/thresholds-fail.config.ts',
+    command: '-c=configs/thresholds-fail.config.js',
     spawnOptions: { cwd: fixtureDir },
     bin: pokuBin,
   });