refactor: apply webpack-defaults

[jhnns]

This PR introduces a breaking change.

This refactoring adds major changes to the loader:

• Remove node 0.10 and node 0.12 support
• The loaded module must now export a function
• This function will be called with the loader options
• This function must return an object with this structure

<outdated, see below>

• The loaded module may flag it's generated value as cacheable

{
    cacheable: true|false,
    ...
}

• The loaded module may also return an array with dependencies that need to be tracked

{
    dependencies: [
        require.resolve('./a.js'),
        require.resolve('./b.js')
    ],
    ...
}

• The function may also return a promise for async results

More details in the README.md

[codecov]

Codecov Report

❗ No coverage uploaded for pull request base (master@d873c86). Click here to learn what that means.
The diff coverage is 100%.

@@           Coverage Diff           @@
##             master    #11   +/-   ##
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  Coverage          ?   100%           
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  Files             ?      1           
  Lines             ?     26           
  Branches          ?      7           
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  Hits              ?     26           
  Misses            ?      0           
  Partials          ?      0

Impacted Files	Coverage Δ
src/index.js	100% <100%> (ø)

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[bebraw]

What would you think of jumping to webpack-defaults?

[jhnns]

Yeah, I will take a look tomorrow 👍

[jhnns]

Switching to webpack-defaults was pretty easy 👍

Please do not merge this PR yet, I haven't finished the README

[jhnns]

I've refactored the proposed API. Excerpt from the README:

---

Examples

If you have a module findAnswer.js like this:

function findAnswer() {
    return {
        code: 'module.exports = 42;'
    };
}

module.exports = findAnswer;

you can use the val-loader to generate source code on build time:

// webpack.config.js
module.exports = {
    ...
    module: {
        rules: [{
            test: require.resolve('path/to/findAnswer.js'),
            use: [{
                loader: 'val-loader'
            }]
        }]
    }
};

---

A complete example of all available features looks like this:

const ask = require('./ask.js');
const generateResult = require('./generateResult.js');

function findAnswer(options) {
    return ask(options.question)
        .then(generateResult)
        .then(result => ({
            
            code: result.code,
            sourceMap: result.sourceMap,
            ast: result.abstractSyntaxTree,
            
            // Mark dependencies of findAnswer().
            // The function will be re-executed if one of these
            // dependencies has changed in watch mode.
            dependencies: [
                // Array of absolute native paths!
                require.resolve('./ask.js'),
                require.resolve('./generateResult.js')
            ],
            
            // Flag the generated code as cacheable.
            // If none of the dependencies have changed,
            // the function won't be executed again.
            cacheable: true

        }));
}

module.exports = findAnswer;

// webpack.config.js
module.exports = {
    ...
    module: {
        rules: [{
            test: require.resolve('path/to/findAnswer.js'),
            use: [{
                loader: 'val-loader',
                options: {
                    question: 'What is the meaning of life?'
                }
            }]
        }]
    }
};

Usage

The module that is loaded with this loader must stick to the following interfaces:

Expected module interface

The loaded module must export a function as default export with the following function interface.

module.exports = function (...) { ... };

Modules transpiled by Babel are also supported.

export default function (...) { ... }

Expected function interface

The function will be called with the loader options and must either return:

• an object with the following object interface or
• a promise that resolves to the following object interface

Expected object interface

Property	Type	Description
code	`string	Buffer`
sourceMap	SourceMap	Optional. Will be pased to the next loader or to webpack.
ast	any	Optional. An Abstract Syntax Tree that will be passed to the next loader. Useful to speed up the build time if the next loader uses the same AST.
dependencies	Array<string>	Default: []. An array of absolute, native paths to file dependencies that need to be watched for changes.
cacheable	boolean	Default: false. Flag whether the code can be re-used in watch mode if none of the dependencies have changed.

Loader Options

The val-loader itself has no options. The options are passed as they are (without cloning them) to the exported function.

[jhnns]

This PR is now mergeable if you're ok with it.

[bebraw]

Only Travis is weird. I wonder if that's something specific in webpack-defaults.

[jhnns]

Yeah, Travis looks broken ^^ I don't get it...

[michael-ciniawsky]

We're experiencing issues processing builds for pull requests - Travis CI Status

Yesterday the build run for hours, not sure why and if it's related to problems @travis, maybe wait 1-2 days 😛

[bebraw]

Based on this error I would say Node 4 is missing some feature you depend on. Fixing that might not fix the whole build, though.

[joshwiens]

@jhnns - The crux of the problem was that the existing travis.yml and the new content were merged & not overwritten ( //cc @sapegin - this should work like the .babelrc )

The merged output was trying to run an OSX matrix which is blocking / can block other build execution which is why it just sat there forever.

[joshwiens]

For reference, whatever the issue is it's specific to NodeJS v4.3 & v4.4

Everything works as expected on NodeJS >=4.5

[jhnns]

@jhnns - The crux of the problem was that the existing travis.yml and the new content were merged & not overwritten ( //cc @sapegin - this should work like the .babelrc )

The merged output was trying to run an OSX matrix which is blocking / can block other build execution which is why it just sat there forever.

That makes sense, thanks for spotting this. I didn't take a close look to be honest 😁

I will fix the buffer issue today.

[bebraw]

The Travis issue should be fixed in webpack-defaults now.

[jhnns]

Only codecov was reporting that there was no coverage report found to compare, so this is safe to merge now. Next step: release