From 6cefc81a1c932abf370614b76f9f84518cc3595b Mon Sep 17 00:00:00 2001
From: Andre Staltz <andre@staltz.com>
Date: Fri, 22 Jul 2016 19:44:33 +0300
Subject: [PATCH] fix(debug): support usage with no argument given

Debug operator should use console.log if no argument if given, but it was crashing with an error.

Closes issue #87.
---
 package.json            |  1 +
 src/core.ts             |  2 +-
 tests/operator/debug.ts | 33 +++++++++++++++++++++++++++++++++
 typings.json            |  4 +++-
 4 files changed, 38 insertions(+), 2 deletions(-)

diff --git a/package.json b/package.json
index 549d1af..b21bf49 100644
--- a/package.json
+++ b/package.json
@@ -55,6 +55,7 @@
     "markdox": "^0.1.10",
     "mkdirp": "^0.5.1",
     "mocha": "^2.4.5",
+    "sinon": "^1.16.0",
     "strip-comments": "^0.4.4",
     "ts-node": "^0.9.0",
     "tslint": "^3.6.0",
diff --git a/src/core.ts b/src/core.ts
index 0e4ce5d..7bfdb20 100644
--- a/src/core.ts
+++ b/src/core.ts
@@ -373,7 +373,7 @@ export class DebugOperator<T> implements Operator<T, T> {
     this.l = '';
     if (typeof arg === 'string') {
       this.l = arg;
-    } else {
+    } else if (typeof arg === 'function') {
       this.s = arg;
     }
   }
diff --git a/tests/operator/debug.ts b/tests/operator/debug.ts
index 46e65d9..abebe60 100644
--- a/tests/operator/debug.ts
+++ b/tests/operator/debug.ts
@@ -2,8 +2,18 @@
 /// <reference path="../../typings/globals/node/index.d.ts" />
 import xs, {Stream, MemoryStream} from '../../src/index';
 import * as assert from 'assert';
+import * as sinon from 'sinon';
 
+var sandbox: sinon.SinonSandbox;
 describe('Stream.prototype.debug', () => {
+  beforeEach(function () {
+    sandbox = sinon.sandbox.create();
+  });
+
+  afterEach(function () {
+    sandbox.restore();
+  });
+
   it('should allow inspecting the operator chain', (done) => {
     const expected = [0, 1, 2];
     const stream = xs.periodic(50).take(3).debug(x => {
@@ -23,6 +33,29 @@ describe('Stream.prototype.debug', () => {
     stream.addListener(listener);
   });
 
+  it('should use console.log if no argument given', (done) => {
+    let stub = sandbox.stub(console, 'log');
+
+    const expected = [0, 1, 2];
+    const stream = xs.periodic(50).take(3).debug();
+
+    assert.doesNotThrow(() => {
+      stream.addListener({
+        next: (x: number) => {
+          assert.equal(x, expected.shift());
+        },
+        error: (err) => done(err),
+        complete: () => {
+          assert.strictEqual(stub.callCount, 3);
+          assert.strictEqual(stub.firstCall.args[0], 0);
+          assert.strictEqual(stub.secondCall.args[0], 1);
+          assert.strictEqual(stub.thirdCall.args[0], 2);
+          done();
+        },
+      });
+    });
+  });
+
   it('should return a Stream if input stream is a Stream', (done) => {
     const input = xs.of<number>(1, 2, 3);
     assert.strictEqual(input instanceof Stream, true);
diff --git a/typings.json b/typings.json
index 925986b..813c146 100644
--- a/typings.json
+++ b/typings.json
@@ -1,7 +1,9 @@
 {
   "name": "xstream",
   "dependencies": {},
-  "devDependencies": {},
+  "devDependencies": {
+    "sinon": "registry:npm/sinon#1.16.0+20160427193336"
+  },
   "globalDependencies": {
     "es6-promise": "registry:dt/es6-promise#0.0.0+20160423074304"
   },