feat(index): support fallback loader options (options.fallback)

[Pimm]

It is now possible to explicitly specify options for the fallback loader.

The fallback option now behaves similar to module.rules.use.

This 1.0.1-based configuration…

{
  test: /\.(?:woff|woff2|eot|ttf|svg)$/,
  use: {
    loader: 'url-loader',
    options: {
      limit: 8192,
      fallback: 'file-loader'
    }
  }
}

…can now be written as

{
  test: /\.(?:woff|woff2|eot|ttf|svg)$/,
  use: {
    loader: 'url-loader',
    options: {
      limit: 8192,
      fallback: {
        loader: 'file-loader'
      }
    }
  }
}

And as one would expect, that means options can be provided, as well…

{
  test: /\.(?:woff|woff2|eot|ttf|svg)$/,
  use: {
    loader: 'url-loader',
    options: {
      limit: 8192,
      fallback: {
        loader: 'file-loader',
        options: {
          name: '[name].[ext]'
        }
      }
    }
  }
}

Please look for potential to break existing configurations and surrounding loaders.

[jsf-clabot]

All committers have signed the CLA.

[alexander-akait]

Very good work! Thanks! Let's add more tests 👍

[alexander-akait]

Let's add tests where name is [hash].[ext] to ensure options will send in fallback.

[alexander-akait]

Need tests

[alexander-akait]

Need tests

[Pimm]

I've added some tests, @ekulabuhov. Please check it out.

[alexander-akait]

Good work! Thanks!

[alexander-akait]

Sorry for big delay, a lot of work, can you add comments in source why we do delete?

[alexander-akait]

Why we remove fallbackLoaderContext.options?

[Pimm]

@evilebottnawi No problem. I've added a few comment lines. Let me know whether this works for you.

[alexander-akait]

Can we move this to src/utils/normalizeFallback.js, in near future we will release new major version url-loader with dropping node@4 and merge this PR. Thanks!

[Pimm]

It's been moved!

[alexander-akait]

👍