feat(bson): test bson in browser

Add support for running bson tests in the browser
via Karma.

Fixes NODE-1504

.travis.yml

@@ -8,6 +8,11 @@ cache:
   directories:
     - node_modules
 
+before_script:
+    - "sudo chown root /opt/google/chrome/chrome-sandbox"
+    - "sudo chmod 4755 /opt/google/chrome/chrome-sandbox"
+    - "npm run build"
+
 node_js:
   - 4
   - 6

karma.conf.js

@@ -0,0 +1,63 @@
+'use strict';
+
+const scenariosPlugin = require('./tools/scenarios-plugin');
+const jsonPlugin = require('rollup-plugin-json');
+const nodeGlobals = require('rollup-plugin-node-globals');
+const nodeBuiltins = require('rollup-plugin-node-builtins');
+const commonjs = require('rollup-plugin-commonjs');
+const nodeResolve = require('rollup-plugin-node-resolve');
+
+const rollupPlugins = [
+  scenariosPlugin(),
+  nodeResolve({
+    browser: true,
+    preferBuiltins: false
+  }),
+  commonjs({
+    namedExports: {
+      'node_modules/buffer/index.js': ['isBuffer']
+    }
+  }),
+  nodeBuiltins(),
+  nodeGlobals(),
+  jsonPlugin()
+];
+
+const rollupConfig = {
+  plugins: rollupPlugins,
+  output: {
+    format: 'iife',
+    name: 'BSONtest',
+    exports: 'named'
+  }
+};
+
+const onwarn = warning => {
+  if (warning.code === 'CIRCULAR_DEPENDENCY' || warning.code === 'EVAL') return;
+  console.warn(warning.toString());
+};
+
+rollupConfig.onwarn = onwarn;
+
+// Karma configuration
+// Generated on Thu Jun 28 2018 14:24:01 GMT-0400 (EDT)
+
+module.exports = function(config) {
+  config.set({
+    basePath: '',
+    frameworks: ['mocha'],
+    reporters: ['mocha'],
+    files: [{ pattern: 'test/node/!(bson_node_only_test).js', watched: false }],
+    preprocessors: {
+      'test/node/!(bson_node_only_test).js': 'rollup'
+    },
+    rollupPreprocessor: rollupConfig,
+    port: 9876,
+    colors: true,
+    logLevel: config.LOG_INFO,
+    autoWatch: true,
+    browsers: ['ChromeHeadless'],
+    singleRun: true,
+    concurrency: Infinity
+  });
+};