Old SVGO errors were not very helpful. Packages like cssnano
(postcss-svgo) had to deal with a lot of issues which are hard to debug
with old errors.
```
Error: Error in parsing SVG: Unquoted attribute value
Line: 1
Column: 29
Char: 6
File: input.svg
```
New errors are more informative and may solve many struggles
```
Error: SvgoParserError: input.svg:2:29: Unquoted attribute value
1 | <svg viewBox="0 0 120 120">
> 2 | <circle fill="#ff0000" cx=60.444444" cy="60" r="50"/>
| ^
3 | </svg>
4 |
```
Mocha doesn't have a lot of features provided by jest.
There is a great assertion library out of the box.
And the most cool feature is inline snapshots.
Mocha also hides errors which makes debugging a nightmare sometimes.
There is a lot of attributes manipulation which is hard to remove at
once. In this diff I added `attributes` object and wrapped it as proxy
for `attrs` field.
Ref https://github.com/syntax-tree/xast
- added type: root | element
- renamed elem to name
- replaced "elem" property checks with check for correct type
Here we add [xast](https://github.com/syntax-tree/xast) support
to three basic nodes: doctype, instruction and comment
Some tests are rewritten instead of checking each field to `.include`
assertion which is able to match shape of object.
Ref https://github.com/svg/svgo/issues/1015
Looks like `sax` is synchronous and we do not need to listen "end"
event. This allows to avoid all callbacks and make `optimize` method
synchronous.
