feat: Set a property in SemanticReleaseError constructor to better support inheritance

Author: pvdlg

README.md

@@ -2,6 +2,10 @@
 
 Error type used by all [semantic-release](https://github.com/semantic-release/semantic-release) packages.
 
+Errors of type `SemanticReleaseError` or an inherited type will be considered by [semantic-release](https://github.com/semantic-release/semantic-release) as an expected exception case (no release to be done, running on a PR etc..). That indicate to the `semantic-release` process to stop and exit with the `0` success code.
+
+Any other type of error will be considered by [semantic-release](https://github.com/semantic-release/semantic-release) as an unexpected error (i/o issue, code problem etc...). That indicate to the `semantic-release` process to stop, log the error and exit with the `1` failure code.
+
 [![npm](https://img.shields.io/npm/v/@semantic-release/error.svg)](https://www.npmjs.com/package/@semantic-release/error)
 [![Greenkeeper badge](https://badges.greenkeeper.io/semantic-release/error.svg)](https://greenkeeper.io/)
 [![license](https://img.shields.io/github/license/semantic-release/error.svg)](https://github.com/semantic-release/error/blob/master/LICENSE)
@@ -25,4 +29,17 @@ throw new SemanticReleaseError('An error happened');
 
 // With error message and error code
 throw new SemanticReleaseError('An error happened', 'ECODE');
+
+// With inheritance
+class InheritedError extends SemanticReleaseError {
+  constructor(message, code, newProperty) {
+    super(message);
+    Error.captureStackTrace(this, this.constructor);
+    this.name = this.constructor.name;
+    this.code = code;
+    this.newProperty = 'newProperty';
+  }
+}
+
+throw new InheritedError('An error happened', 'ECODE');
 ```

index.js

@@ -4,5 +4,6 @@ module.exports = class SemanticReleaseError extends Error {
     Error.captureStackTrace(this, this.constructor);
     this.name = this.constructor.name;
     this.code = code;
+    this.semanticRelease = true;
   }
 };

test/helpers/inherited-error.js

@@ -0,0 +1,11 @@
+import SemanticReleaseError from '../../index';
+
+export default class InheritedError extends SemanticReleaseError {
+  constructor(message, code, newProperty) {
+    super(message);
+    Error.captureStackTrace(this, this.constructor);
+    this.name = this.constructor.name;
+    this.code = code;
+    this.newProperty = 'newProperty';
+  }
+}

test/helpers/throw-inherited-error.js

@@ -0,0 +1,5 @@
+import InheritedError from './inherited-error';
+
+export default () => {
+  throw new InheritedError('message', 'code');
+};

test/index.test.js

@@ -1,18 +1,24 @@
 import test from 'ava';
 import SemanticReleaseError from '../index';
 import throwError from './helpers/throw-error';
+import InheritedError from './helpers/inherited-error';
+import throwInheritedError from './helpers/throw-inherited-error';
 
 test('Instanciates error', t => {
   const error = new SemanticReleaseError();
 
   t.true(error instanceof Error);
+  t.true(error.semanticRelease);
+  t.true(error instanceof SemanticReleaseError);
 });
 
 test('Sets message', t => {
   const message = 'foo';
   const error = new SemanticReleaseError(message);
 
   t.is(error.message, message);
+  t.true(error.semanticRelease);
+  t.true(error instanceof SemanticReleaseError);
 });
 
 test('Sets message and code', t => {
@@ -22,10 +28,22 @@ test('Sets message and code', t => {
 
   t.is(error.code, code);
   t.is(error.message, message);
+  t.true(error.semanticRelease);
+  t.true(error instanceof SemanticReleaseError);
 });
 
 test('Include the stacktrace and name', async t => {
   const error = await t.throws(() => throwError());
   t.regex(error.stack, /helpers\/throw-error/);
   t.is(error.name, 'SemanticReleaseError');
+  t.true(error.semanticRelease);
+  t.true(error instanceof SemanticReleaseError);
+});
+
+test('Include "semanticRelease" property in inherited errors', async t => {
+  const error = await t.throws(() => throwInheritedError());
+  t.regex(error.stack, /helpers\/throw-inherited-error/);
+  t.is(error.name, 'InheritedError');
+  t.true(error instanceof InheritedError);
+  t.true(error.semanticRelease);
 });