Complete code coverage

[atjn]

This PR adds three new tests which bumps the code coverage to 100%. I hope you like them!

Closes #55

[coveralls]

Coverage remained the same at 100.0% when pulling 0dc4ee1 on atjn:test-coverage into c45992b on coderaiser:master.

[atjn]

I'm not sure how coveralls concluded that coverage already was 100%. Here's what my terminal says:

Before:

-----------|---------|----------|---------|---------|-------------------
File       | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s 
-----------|---------|----------|---------|---------|-------------------
All files  |     100 |    84.62 |     100 |     100 |                   
 css.js    |     100 |       80 |     100 |     100 | 27                
 html.js   |     100 |      100 |     100 |     100 |                   
 img.js    |     100 |    66.67 |     100 |     100 | 29                
 js.js     |     100 |      100 |     100 |     100 |                   
 minify.js |     100 |       80 |     100 |     100 | 32,71             
-----------|---------|----------|---------|---------|-------------------

After:

-----------|---------|----------|---------|---------|-------------------
File       | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s 
-----------|---------|----------|---------|---------|-------------------
All files  |     100 |      100 |     100 |     100 |                   
 css.js    |     100 |      100 |     100 |     100 |                   
 html.js   |     100 |      100 |     100 |     100 |                   
 img.js    |     100 |      100 |     100 |     100 |                   
 js.js     |     100 |      100 |     100 |     100 |                   
 minify.js |     100 |      100 |     100 |     100 |                   
-----------|---------|----------|---------|---------|-------------------

[coderaiser]

Nice, thank you :)