From 21100a0a8b5e2db75c40c001d049ba3787f75192 Mon Sep 17 00:00:00 2001
From: Kyle Shockey <shockey@users.noreply.github.com>
Date: Thu, 22 Jun 2017 22:05:38 -0700
Subject: [PATCH 1/2] Don't render Markdown if input or sanitized input is
 empty

---
 src/core/components/providers/markdown.jsx | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/src/core/components/providers/markdown.jsx b/src/core/components/providers/markdown.jsx
index d058d17617f..8ebce12c0c0 100644
--- a/src/core/components/providers/markdown.jsx
+++ b/src/core/components/providers/markdown.jsx
@@ -11,6 +11,12 @@ const sanitizeOptions = {
 
 function Markdown({ source }) {
   const sanitized = sanitize(source, sanitizeOptions)
+
+  // sometimes the sanitizer returns "undefined" as a string
+  if(!source || !sanitized || sanitized === "undefined") {
+    return null
+  }
+
   return <Remarkable
     options={{html: true, typographer: true, linkify: true, linkTarget: "_blank"}}
     source={sanitized}

From 2fb04c286b22a7e22dd808eba60603d7464e1059 Mon Sep 17 00:00:00 2001
From: Kyle Shockey <shockey@users.noreply.github.com>
Date: Thu, 22 Jun 2017 22:11:37 -0700
Subject: [PATCH 2/2] Add tests

---
 test/bugs/3279-empty-markdown-source.js | 37 +++++++++++++++++++++++++
 1 file changed, 37 insertions(+)
 create mode 100644 test/bugs/3279-empty-markdown-source.js

diff --git a/test/bugs/3279-empty-markdown-source.js b/test/bugs/3279-empty-markdown-source.js
new file mode 100644
index 00000000000..276c87d1e27
--- /dev/null
+++ b/test/bugs/3279-empty-markdown-source.js
@@ -0,0 +1,37 @@
+/* eslint-env mocha */
+import React from "react"
+import expect from "expect"
+import { render } from "enzyme"
+import Markdown from "components/providers/markdown"
+
+describe("UI-3279: Empty Markdown inputs causing bare `undefined` in output", function(){
+  it("should return no text for `null` as source input", function(){
+    let props = {
+      source: null
+    }
+
+    let el = render(<Markdown {...props}/>)
+
+    expect(el.text()).toEqual("")
+  })
+
+  it("should return no text for `undefined` as source input", function(){
+    let props = {
+      source: undefined
+    }
+
+    let el = render(<Markdown {...props}/>)
+
+    expect(el.text()).toEqual("")
+  })
+
+  it("should return no text for empty string as source input", function(){
+    let props = {
+      source: ""
+    }
+
+    let el = render(<Markdown {...props}/>)
+
+    expect(el.text()).toEqual("")
+  })
+})