If each test case a html file, it results in too many html files added,
which are hard to visit by category and management. If adding multiple
test cases in one file, not easy to find a rule about which case should
be in which file.
In my opinion, it essentially the same as "how to classify test cases".
We used to write test cases in this framework:
```js
describe('some test suite', function () {
it('a test case', function () {
});
});
```
Similarly,
a-test-file.html
test-case-chart1
test-case-chart2
...
I have been generating test html file (Can be considered as a test suite)
based on `echarts/test/tmp-base.html`.
And add charts (can be considered as test cases) into the file.
Test suites can be classify by features in coarse granularity.
For example, add cases about "hover state" into "hoverStyle.html",
add cases about large bar into "bar-large.html".
I think I can add a command line tool to generate a test html file.
And we should probably have some guide or rule of the naming of these file.
For example,
the name should be started by
+ a chart name (like, `line-xxx-xxx.html`)
+ or a component name (like, `visualMap-xxx-xxx.html` or
`visual-map-xxx-xxx.hmtml` ? )
+ or a common feature name (like, `haveStyle.html`, `label-xxx-xxx.html`)
