error creator

src/error.js

@@ -0,0 +1,27 @@
+/**
+ * Creates an observable that immediately terminates with the provided error
+ *
+ * @example
+ * error('error message').subscribe({ error: console.log }) // logs 'error message'
+ *
+ * @example
+ * // rejecting a certain case
+ * stream
+ *  .filter(specificCase)
+ *  .flatMap(value => Observable.error(value))
+ *  .subscribe(observer)
+ *
+ * @param  {*}          e Error value
+ * @return {Observable} New Observable
+ */
+function error(e) {
+  const Constructor = this || Observable;
+
+  return new Constructor(observer => {
+    observer.error(e);
+  });
+}
+
+error._name = 'error';
+
+export default error;

src/index.js

@@ -4,6 +4,7 @@ import addCreators from './addCreators';
 import catchError from './catchError';
 import debounce from './debounce';
 import defer from './defer';
+import error from './error';
 import filter from './filter';
 import flatMap from './flatMap';
 import forEach from './forEach';
@@ -19,7 +20,7 @@ import toArray from './toArray';
 import transform from './transform';
 
 const addAll = (target = Observable) => {
-  addCreators(target, [defer, fromEvent, fromPromise, interval]);
+  addCreators(target, [defer, error, fromEvent, fromPromise, interval]);
 
   addOperators(target.prototype, [
     catchError,
@@ -44,6 +45,7 @@ export {
   catchError,
   debounce,
   defer,
+  error,
   filter,
   flatMap,
   forEach,

test/error.js

@@ -0,0 +1,18 @@
+import { expect } from 'chai';
+import sinon from 'sinon';
+import error from '../src/error';
+import apiCheck from './common/apiCheck';
+
+describe('(Creator) error', () => {
+  apiCheck(error);
+
+  it('should return an Observable', () => {
+    expect(error(Promise.resolve())).to.be.an.instanceOf(Observable);
+  });
+
+  it('should trigger an Observable error event with the provided value', () => {
+    const observer = { error: sinon.spy() };
+    error('error').subscribe(observer);
+    expect(observer.error).to.have.been.calledWith('error');
+  });
+});