Support Webpack MultiCompiler (#9)

* Support Webpack MultiCompiler

Author: richardscarrott

.gitignore

@@ -1 +1,3 @@
-node_modules/
+node_modules/
+.log
+test/fixtures/**/dist

src/friendly-errors-plugin.js

@@ -6,7 +6,10 @@ const os = require('os');
 const transformErrors = require('./core/transformErrors');
 const formatErrors = require('./core/formatErrors');
 const output = require('./output');
-const concat = require('./utils').concat;
+const utils = require('./utils');
+
+const concat = utils.concat;
+const uniqueBy = utils.uniqueBy;
 
 const defaultTransformers = [
   require('./transformers/babelSyntax'),
@@ -44,12 +47,12 @@ class FriendlyErrorsWebpackPlugin {
       }
 
       if (hasErrors) {
-        this.displayErrors(stats.compilation.errors, 'error');
+        this.displayErrors(extractErrorsFromStats(stats, 'errors'), 'error');
         return;
       }
 
       if (hasWarnings) {
-        this.displayErrors(stats.compilation.warnings, 'warning');
+        this.displayErrors(extractErrorsFromStats(stats, 'warnings'), 'warning');
       }
     });
 
@@ -66,7 +69,7 @@ class FriendlyErrorsWebpackPlugin {
   }
 
   displaySuccess(stats) {
-    const time = stats.endTime - stats.startTime;
+    const time = getCompileTime(stats);
     output.title('success', 'DONE', 'Compiled successfully in ' + time + 'ms');
 
     if (this.compilationSuccessInfo.messages) {
@@ -98,6 +101,31 @@ class FriendlyErrorsWebpackPlugin {
   }
 }
 
+function extractErrorsFromStats(stats, type) {
+  if (isMultiStats(stats)) {
+    const errors = stats.stats
+      .reduce((errors, stats) => errors.concat(extractErrorsFromStats(stats, type)), []);
+    // Dedupe to avoid showing the same error many times when multiple
+    // compilers depend on the same module.
+    return uniqueBy(errors, error => error.message);
+  }
+  return stats.compilation[type];
+}
+
+function getCompileTime(stats) {
+  if (isMultiStats(stats)) {
+    // Webpack multi compilations run in parallel so using the longest duration.
+    // https://webpack.github.io/docs/configuration.html#multiple-configurations
+    return stats.stats
+      .reduce((time, stats) => Math.max(time, getCompileTime(stats)), 0);
+  }
+  return stats.endTime - stats.startTime;
+}
+
+function isMultiStats(stats) {
+  return stats.stats;
+}
+
 function getMaxSeverityErrors(errors) {
   const maxSeverity = getMaxInt(errors, 'severity');
   return errors.filter(e => e.severity === maxSeverity);

src/utils/index.js

@@ -10,6 +10,22 @@ function concat() {
   return Array.prototype.concat.apply(baseArray, args.slice(1));
 }
 
+/**
+ * Dedupes array based on criterion returned from iteratee function.
+ * Ex: uniqueBy(
+ *     [{ id: 1 }, { id: 1 }, { id: 2 }],
+ *     val => val.id
+ * ) = [{ id: 1 }, { id: 2 }]
+ */
+function uniqueBy(arr, fun) {
+  const seen = {};
+  return arr.filter(el => {
+    const e = fun(el);
+    return !(e in seen) && (seen[e] = 1);
+  })
+}
+
 module.exports = {
-  concat: concat
-};
+  concat: concat,
+  uniqueBy: uniqueBy
+};

test/fixtures/eslint-warnings/webpack.config.js

@@ -11,19 +11,18 @@ module.exports = {
 
   ],
   module: {
-    preLoaders: [
+    loaders: [
       {
         test: /\.js$/,
         loader: 'eslint',
+        enforce: 'pre',
         include: __dirname
-      }
-    ],
-    loaders: [
+      },
       {
         test: /\.jsx?$/,
         loader: 'babel',
         exclude: /node_modules/
       }
     ]
   }
-};
+};

test/fixtures/multi-compiler-module-errors/index.js

@@ -0,0 +1 @@
+require('./non-existing');

test/fixtures/multi-compiler-module-errors/index2.js

@@ -0,0 +1 @@
+require('not-found');

test/fixtures/multi-compiler-module-errors/webpack.config.js

@@ -0,0 +1,16 @@
+module.exports = [
+    {
+      entry: __dirname + "/index.js",
+      output: {
+        path: __dirname + "/dist",
+        filename: "bundle.js"
+      }
+    },
+    {
+      entry: __dirname + "/index2.js",
+      output: {
+        path: __dirname + "/dist",
+        filename: "bundle2.js"
+      }
+    }
+];

test/fixtures/multi-compiler-success/index.js

@@ -0,0 +1 @@
+module.exports = 'I am an entry point';

test/fixtures/multi-compiler-success/index2.js

@@ -0,0 +1 @@
+module.exports = 'I am another entry point';

test/fixtures/multi-compiler-success/webpack.config.js

@@ -0,0 +1,16 @@
+module.exports = [
+    {
+      entry: __dirname + "/index.js",
+      output: {
+        path: __dirname + "/dist",
+        filename: "bundle.js"
+      }
+    },
+    {
+      entry: __dirname + "/index2.js",
+      output: {
+        path: __dirname + "/dist",
+        filename: "bundle2.js"
+      }
+    }
+];