fix: resolve dinero.js factory regardless of CJS/ESM resolution

.changeset/fix-dinero-interop.md

@@ -0,0 +1,5 @@
+---
+"@epilot/pricing": patch
+---
+
+Fix `TypeError: (0, x.default) is not a function` when a consumer bundles `@epilot/pricing` with `mainFields: ['module','main']`. The `dinero.js` factory is now resolved regardless of whether the CJS or ESM build is picked up.

src/bundle-interop.test.ts

@@ -0,0 +1,55 @@
+import { execFileSync } from 'node:child_process';
+import fs from 'node:fs';
+import os from 'node:os';
+import path from 'node:path';
+import { build } from 'esbuild';
+import { beforeAll, describe, expect, it } from 'vitest';
+
+const root = path.resolve(__dirname, '..');
+
+/**
+ * Regression: consumers that bundle this package's CJS entry with
+ * `mainFields: ['module', 'main']` resolved `require('dinero.js')` to dinero's ESM build, so
+ * `.default` was the module namespace and `formatAmount` threw
+ * "TypeError: (0, x.default) is not a function".
+ */
+describe('dist bundle interop', () => {
+  beforeAll(() => {
+    execFileSync('node', ['esbuild.config.js'], { cwd: root, stdio: 'ignore' });
+  }, 60_000);
+
+  it('keeps dinero.js external in dist', () => {
+    for (const file of ['dist/cjs/index.cjs', 'dist/esm/index.mjs']) {
+      const code = fs.readFileSync(path.join(root, file), 'utf8');
+      expect(code).toMatch(/require\(["']dinero\.js["']\)|from\s*["']dinero\.js["']/);
+    }
+  });
+
+  it.each([
+    ['cjs', 'dist/cjs/index.cjs'],
+    ['esm', 'dist/esm/index.mjs'],
+  ] as const)('formatAmount works when the %s entry is re-bundled with mainFields module,main', async (_, entry) => {
+    const dir = fs.mkdtempSync(path.join(os.tmpdir(), 'pricing-interop-'));
+    try {
+      const outfile = path.join(dir, 'out.mjs');
+      await build({
+        stdin: {
+          contents: `import { formatAmount } from ${JSON.stringify(path.join(root, entry))};
+console.log(formatAmount({ amount: 12345, currency: 'EUR', locale: 'en' }));`,
+          resolveDir: root,
+        },
+        outfile,
+        bundle: true,
+        platform: 'node',
+        format: 'esm',
+        mainFields: ['module', 'main'],
+        banner: { js: "import { createRequire } from 'module'; const require = createRequire(import.meta.url);" },
+        logLevel: 'silent',
+      });
+      const out = execFileSync('node', [outfile], { encoding: 'utf8' });
+      expect(out).toMatch(/123[.,]45/);
+    } finally {
+      fs.rmSync(dir, { recursive: true, force: true });
+    }
+  });
+});

src/money/dinero.ts

@@ -0,0 +1,20 @@
+import * as DineroModule from 'dinero.js';
+import type DineroFactory from 'dinero.js';
+
+/**
+ * dinero.js v1 ships a CJS build (`main`) and an ESM build (`module`, `export default`).
+ * When a consumer bundles this package's CJS entry with `mainFields: ['module', 'main']`
+ * (e.g. esbuild for Lambdas), `require('dinero.js')` resolves to the ESM build and the
+ * default import becomes the module namespace instead of the factory
+ * ("TypeError: (0, x.default) is not a function"). Unwrap nested `default`s so the factory
+ * is found regardless of how the consumer resolved the package.
+ */
+const resolveFactory = (mod: unknown): typeof DineroFactory => {
+  let current = mod as { default?: unknown };
+  for (let depth = 0; depth < 3 && typeof current !== 'function'; depth++) {
+    current = current?.default as { default?: unknown };
+  }
+  return current as unknown as typeof DineroFactory;
+};
+
+export const dinero = resolveFactory(DineroModule);

src/money/formatters.ts

@@ -1,4 +1,3 @@
-import dinero from 'dinero.js';
 import type { Currency } from 'dinero.js';
 import { CURRENCIES_SUBUNITS, DEFAULT_CURRENCY, DEFAULT_SUBUNIT } from './constants';
 import {
@@ -10,6 +9,7 @@ import {
   GENERIC_UNIT_DISPLAY_LABEL,
   MAX_SUPPORTED_FORMAT_PRECISION,
 } from './constants';
+import { dinero } from './dinero';
 import { getCurrencySymbol } from './get-currency-symbol';
 import { toDinero } from './to-dinero';
 

src/money/to-dinero.ts

@@ -1,6 +1,7 @@
-import dinero, { type Currency, type Dinero } from 'dinero.js';
+import type { Currency, Dinero } from 'dinero.js';
 import { DEFAULT_CURRENCY } from './constants';
 import { DECIMAL_PRECISION } from './constants';
+import { dinero } from './dinero';
 
 /**
  * Utility mapper from Integer amount into DineroJS object using DECIMAL_PRECISION (12).