add Source.fail

srijs · May 22, 2016 · d83ee6d · d83ee6d
1 parent e0984d6
commit d83ee6d
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diff --git a/src/source-spec.ts b/src/source-spec.ts
@@ -45,6 +45,16 @@ describe('Stream', () => {
 
     });
 
+    describe('fail', () => {
+
+      it('throws an error', () => {
+        const reason = new Error('some error');
+        const src = Source.fail(reason);
+        return chai.expect(src.toArray()).to.eventually.be.rejectedWith(reason);
+      });
+
+    });
+
     describe('concat', () => {
 
       it('concatenates two empty sources', () => {

diff --git a/src/source.ts b/src/source.ts
@@ -23,6 +23,12 @@ export class Source<Output> {
     });
   }
 
+  static fail<Output>(reason: Error): Source<Output> {
+    return new Source(<State, Result>(sink: SinkInterface<Output, State, Result>) => {
+      return Promise.reject<Result>(reason);
+    });
+  }
+
   concat(next: Source<Output>): Source<Output> {
     return this.concatAsync(Promise.resolve(next));
   }