CORS breaks existing unit testing approach

[fabiodrg]

The current unit test approach relies on loading HTML files dynamically and updating the jQuery context. Loading the HTML file results in a GET request with the file protocol. Well, it seems both Firefox and Chrome's CORS (Cross-Origin Resource Sharing) policies are stricter.

Access to XMLHttpRequest at 'file:///.../SigTools/src/test/pages/datatables/single_row.html' from origin 'null' has been blocked by CORS policy: Cross origin requests are only supported for protocol schemes: http, data, chrome, chrome-extension, chrome-untrusted, https.

I think the error message is quite clear. The easiest solution, I can think of, is to launch a small server on development mode that serves the test HTML files. However, the server must also add the header Access-Control-Allow-Origin: * to all responses.

• [x] Launch a local web server on /src/test, with a fixed port (customizable env environment is a bonus). Since with already have node, perhaps is the easiest way to create the said server
• [x] Ensure the web server attaches Access-Control-Allow-Origin: * on all responses
• [x] Add a prefix with the address for the local web server on all requested HTML files. Update it here: https://github.com/msramalho/SigTools/blob/533ebb7cee60e8b44aa7281364fdef1f0ab14194/src/test/setup.js#L5,

I think this is enough!

[fabiodrg]

Just lost 15 minutes because the browser was caching the test HTML file... if we implement the web server, I believe there is a header in the response to tell browsers "do not cache this resource"! Might be useful