Update karma configuration

- Fixes a weird bug where tensors were spuriously disposed by tfjs in testing environment due to there being multiple tfjs instances present on the page from the different builds
- Improves stack traces to make debugging easier by disabling minification in karma webpack.
- Only webpack the main package, this means that the test files have to use the global ml5 object.

Author: meiamsome

karma.conf.js

@@ -2,17 +2,42 @@ module.exports = (config) => {
   config.set({
     frameworks: ['jasmine'],
     files: [
+      'src/index.js',
       'src/**/*_test.js',
     ],
     preprocessors: {
-      'src/**/*_test.js': ['webpack'],
+      'src/index.js': ['webpack'],
     },
     webpack: {
-      // karma watches the test entry points
-      // (you don't need to specify the entry option)
-      // webpack watches dependencies
-
-      // webpack configuration
+      // TODO: This is duplication of the webpack.common.babel.js file, but they
+      // use different import syntaxes so it's not easy to just require it here.
+      // Maybe this could be put into a JSON file, but the include in the module
+      // rules is dynamic.
+      entry: ['babel-polyfill', './src/index.js'],
+      output: {
+        libraryTarget: 'umd',
+        filename: 'ml5.js',
+        library: 'ml5',
+      },
+      module: {
+        rules: [
+          {
+            enforce: 'pre',
+            test: /\.js$/,
+            exclude: /node_modules/,
+            loader: 'eslint-loader',
+          },
+          {
+            test: /\.js$/,
+            loader: 'babel-loader',
+            include: require('path').resolve(__dirname, 'src'),
+          },
+        ],
+      },
+      // Don't minify the webpack build for better stack traces
+      optimization: {
+        minimize: false,
+      },
     },
     webpackMiddleware: {
       noInfo: true,

src/ImageClassifier/index_test.js

@@ -1,6 +1,6 @@
 /* eslint new-cap: 0 */
 
-import * as ImageClassifier from './index';
+const { ImageClassifier } = ml5;
 
 const DEFAULTS = {
   learningRate: 0.0001,