fix: 🐛 mocks process.emitWarning for browser compatibility

closes #374

Author: pizzafroide

src/process.ts

@@ -6,6 +6,7 @@ export interface IProcess {
   cwd(): string;
   platform: string;
   nextTick: (callback: (...args) => void, ...args) => void;
+  emitWarning: (message: string, type: string) => void;
   env: {
     MEMFS_DONT_WARN?: boolean;
   };
@@ -23,6 +24,11 @@ export function createProcess(p: IProcess = process): IProcess {
   if (!p.getgid) p.getgid = () => 0;
   if (!p.cwd) p.cwd = () => '/';
   if (!p.nextTick) p.nextTick = require('./setImmediate').default;
+  if (!p.emitWarning)
+    p.emitWarning = (message, type) => {
+      // tslint:disable-next-line:no-console
+      console.warn(`${type}${type ? ': ' : ''}${message}`);
+    };
   if (!p.env) p.env = {};
   return p;
 }

src/volume.ts

@@ -582,7 +582,7 @@ export class Volume {
   get promises() {
     if (promisesWarn) {
       promisesWarn = false;
-      require('process').emitWarning('The fs.promises API is experimental', 'ExperimentalWarning');
+      process.emitWarning('The fs.promises API is experimental', 'ExperimentalWarning');
     }
     if (this.promisesApi === null) throw new Error('Promise is not supported in this environment.');
     return this.promisesApi;