Add support to JupyterLab 2

[martinRenou]

No description provided.

[jasongrout]

This PR looks right. Did you test it by generating a plugin and seeing if it works in jlab 1 and 2?

[martinRenou]

I did not but I should have, the build seems to fail with

src/plugin.ts(29,3): error TS2322: Type 'Token<IJupyterWidgetRegistry>[]' is not assignable to type 'Token<any>[]'.
      Type 'Token<IJupyterWidgetRegistry>' is not assignable to type 'Token<any>'.
        Types have separate declarations of a private property '_tokenStructuralPropertyT'.

Not sure I get the error I am not familiar with this Token system in JLab

[jasongrout]

Is this the jlab build when installing the plugin? For jlab 1 or jlab 2?

[martinRenou]

I seem to reproduce this error locally with JupyterLab 1.2.6 and JupyterLab 2.0.0

[vidartf]

This is because the plugin is strongly typed:

widget-ts-cookiecutter/{{cookiecutter.github_project_name}}/src/plugin.ts

Line 27 in f41a766

const examplePlugin: IPlugin<Application<Widget>, void> = {

Ref jupyter-widgets/ipywidgets#2798 (comment)

[jasongrout]

@martinRenou - can you check out the last few commits I added to this PR? I think it works now in jlab 2.

[martinRenou]

I pushed a commit but it is still failing.

I feel like it has to do with Karma not understanding ES6.

[vidartf]

@martinRenou It should work with this code (might need to adjust some paths) https://github.com/vidartf/opinionated-widget-cookiecutter/blob/master/%7B%7Bcookiecutter.github_project_name%7D%7D/ts/tests/karma.conf.js

[vidartf]

Ah, and with these: https://github.com/vidartf/opinionated-widget-cookiecutter/blob/b94f8a16c55a5f0014b2cfe41a0d0836b0fa469f/%7B%7Bcookiecutter.github_project_name%7D%7D/ts/package.json#L70-L71