added unit tests for lib/markdown

tests/fixtures/markdowns.js

@@ -0,0 +1,48 @@
+const basic = `
+# Welcome to Boostnote!
+## Click here to edit markdown :wave:
+
+<iframe width="560" height="315" src="https://www.youtube.com/embed/L0qNPLsvmyM" frameborder="0" allowfullscreen></iframe>
+
+## Docs :memo:
+- [Boostnote | Boost your happiness, productivity and creativity.](https://hackernoon.com/boostnote-boost-your-happiness-productivity-and-creativity-315034efeebe)
+- [Cloud Syncing & Backups](https://github.com/BoostIO/Boostnote/wiki/Cloud-Syncing-and-Backup)
+- [How to sync your data across Desktop and Mobile apps](https://github.com/BoostIO/Boostnote/wiki/Sync-Data-Across-Desktop-and-Mobile-apps)
+- [Convert data from **Evernote** to Boostnote.](https://github.com/BoostIO/Boostnote/wiki/Evernote)
+- [Keyboard Shortcuts](https://github.com/BoostIO/Boostnote/wiki/Keyboard-Shortcuts)
+- [Keymaps in Editor mode](https://github.com/BoostIO/Boostnote/wiki/Keymaps-in-Editor-mode)
+- [How to set syntax highlight in Snippet note](https://github.com/BoostIO/Boostnote/wiki/Syntax-Highlighting)
+
+---
+
+## Article Archive :books:
+- [Reddit English](http://bit.ly/2mOJPu7)
+- [Reddit Spanish](https://www.reddit.com/r/boostnote_es/)
+- [Reddit Chinese](https://www.reddit.com/r/boostnote_cn/)
+- [Reddit Japanese](https://www.reddit.com/r/boostnote_jp/)
+
+---
+
+## Community :beers:
+- [GitHub](http://bit.ly/2AWWzkD)
+- [Twitter](http://bit.ly/2z8BUJZ)
+- [Facebook Group](http://bit.ly/2jcca8t)
+`
+
+const codeblock = `
+\`\`\`js:filename.js:2
+var project = 'boostnote';
+\`\`\`
+`
+
+const katex = `
+$$
+c = \pm\sqrt{a^2 + b^2}
+$$
+`
+
+export default {
+  basic,
+  codeblock,
+  katex
+}