feat: add errorToJSON function

Author: joshunrau

src/__tests__/exception.test.ts

@@ -1,7 +1,15 @@
 import type { Simplify } from 'type-fest';
 import { describe, expect, expectTypeOf, it, test } from 'vitest';
 
-import { BaseException, ExceptionBuilder, OutOfRangeException, parseStack, ValueException } from '../exception.js';
+import {
+  BaseException,
+  errorToJSON,
+  ExceptionBuilder,
+  OutOfRangeException,
+  parseStack,
+  RuntimeException,
+  ValueException
+} from '../exception.js';
 import { Err } from '../vendor/neverthrow.js';
 
 import type { ExceptionConstructor } from '../exception.js';
@@ -194,7 +202,31 @@ describe('parseStack', () => {
   it('should return the same value, in terms of value, whether called with an error or a string', () => {
     const error = new Error();
     const r1 = parseStack(error);
-    const r2 = parseStack(error.stack!);
+    const r2 = parseStack(error.stack);
     expect(r1).toStrictEqual(r2);
   });
 });
+
+describe('errorToJSON', () => {
+  it('should return the expected output', () => {
+    const cause = new RuntimeException('Something else went wrong', {
+      details: {
+        foo: true
+      }
+    });
+    const error = new Error('Something went wrong', { cause });
+    expect(JSON.parse(errorToJSON(error))).toStrictEqual({
+      cause: {
+        details: {
+          foo: true
+        },
+        message: 'Something else went wrong',
+        name: 'RuntimeException',
+        stack: expect.toSatisfy((arg) => Array.isArray(arg) && arg.every((item) => typeof item === 'string'))
+      },
+      message: 'Something went wrong',
+      name: 'Error',
+      stack: expect.toSatisfy((arg) => Array.isArray(arg) && arg.every((item) => typeof item === 'string'))
+    });
+  });
+});

src/exception.ts

@@ -4,6 +4,7 @@
 
 import cleanStack from 'clean-stack';
 import extractStack from 'extract-stack';
+import { isErrorLike, serializeError } from 'serialize-error';
 import stringifyObject from 'stringify-object';
 import type { IsNever, RequiredKeysOf } from 'type-fest';
 import type { z } from 'zod';
@@ -70,6 +71,18 @@ function parseStack(errorOrStack: Error | string | undefined): string[] {
   return extractStack.lines(cleanStack(stack, { pretty: true }));
 }
 
+function errorToJSON(error: Error): string {
+  const serialize = (error: Error): { [key: string]: unknown } => {
+    const { cause, stack, ...serialized } = serializeError(error);
+    return {
+      ...serialized,
+      cause: isErrorLike(cause) ? serialize(cause) : cause,
+      stack: parseStack(stack)
+    };
+  };
+  return JSON.stringify(serialize(error), null, 2);
+}
+
 abstract class BaseException<TParams extends ExceptionParams, TOptions extends ExceptionOptions>
   extends Error
   implements ExceptionLike
@@ -231,4 +244,14 @@ export type {
   ExceptionStatic,
   ExceptionType
 };
-export { BaseException, ExceptionBuilder, OutOfRangeException, parseStack, RuntimeException, ValueException };
+
+export {
+  BaseException,
+  errorToJSON,
+  ExceptionBuilder,
+  OutOfRangeException,
+  parseStack,
+  RuntimeException,
+  serializeError,
+  ValueException
+};