Add spike processed file outPath option

lib/plugin.js

@@ -66,7 +66,9 @@ module.exports = class SpikeWebpackPlugin {
           : JSON.parse(dep._source._value.replace(/^module\.exports = /, ''))
 
         // calculate the output path
-        let outputPath = this.util.getOutputPath(f.path).relative
+        // this will use the special prop f.outPath as an override, which can
+        // be set by plugins to create a custom output path
+        let outputPath = this.util.getOutputPath(f.outPath || f.path).relative
 
         // set the file's extension if necessary
         if (f.extension) {

test/fixtures/plugins/custom_output.html

@@ -0,0 +1 @@
+<p>my output path was rewritten by a plugin : (</p>

test/fixtures/plugins/plugin.js

@@ -4,11 +4,19 @@ module.exports = class JadeWebpackPlugin {
   }
 
   apply (compiler) {
-    compiler.plugin('run', function (compilation, done) {
-      setTimeout(function () {
+    compiler.plugin('run', (compilation, done) => {
+      setTimeout(() => {
         compiler.options.test = 'bar'
         done()
       }, 300)
     })
+
+    compiler.plugin('emit', (compilation, done) => {
+      const file = compiler.options.spike.files.process.find((f) => {
+        if (f.path.match(/custom_output/)) { return f }
+      })
+      file.outPath = file.path.replace(/custom_output/, 'changed_output')
+      done()
+    })
   }
 }

test/plugins.js

@@ -2,11 +2,13 @@ const test = require('ava')
 const path = require('path')
 const {compileFixture, fs} = require('./_helpers')
 
-test('compiles a project with a custom plugin', (t) => {
+test('compiles a project with a custom plugin, plugins can change output path', (t) => {
   return compileFixture(t, 'plugins')
     .then(({res, publicPath}) => {
       const index = path.join(publicPath, 'index.html')
+      const outputChanged = path.join(publicPath, 'changed_output.html')
       fs.statSync(index)
+      fs.statSync(outputChanged)
       t.truthy(res.stats.compilation.options.test === 'bar')
     })
 })