feat(volume): add caseSensitive option

src/__tests__/volume.test.ts

@@ -1054,6 +1054,31 @@ describe('volume', () => {
         expect(typeof vol.promises).toBe('object');
       });
     });
+    describe('caseSensitive: false', () => {
+      it('is case insensitive', () => {
+        const vol = new Volume(undefined, false);
+        vol.mkdirSync('/dir');
+        vol.writeFileSync('/Dir/Foo.txt', 'foo');
+        expect(vol.readFileSync('/dir/foo.TXT', {encoding: 'utf8'})).toBe('foo');
+        vol.unlinkSync('/dir/foo.txt');
+        expect(vol.existsSync('/Dir/Foo.txt')).toBe(false)
+      });
+      it('preserve original filename casing', () => {
+        const vol = new Volume(undefined, false);
+        vol.fromJSON({
+          '/Dir': null,
+          '/dir': null,
+          '/fileA.txt': '1',
+          '/filea.txt': '2',
+          '/FileB.txt': '1',
+          '/fileb.txt': '2',
+        });
+        expect(vol.readdirSync('/', {encoding: 'utf8'})).toEqual(['Dir', 'fileA.txt', 'FileB.txt']);
+        expect((vol.readdirSync('/', {encoding: 'utf8', withFileTypes: true}) as Dirent[]).map(({name}) => name)).toEqual(['Dir', 'fileA.txt', 'FileB.txt']);
+        expect(vol.readFileSync('/fileA.txt', {encoding: 'utf8'})).toBe('2');
+        expect(vol.readFileSync('/FileB.txt', {encoding: 'utf8'})).toBe('2');
+      });
+    });
   });
   describe('StatWatcher', () => {
     it('.vol points to current volume', () => {

src/node.ts

@@ -283,7 +283,7 @@ export class Link extends EventEmitter {
   }
 
   setChild(name: string, link: Link = new Link(this.vol, this, name)): Link {
-    this.children[name] = link;
+    this.children[this.vol.caseSensitive ? name : name.toLowerCase()] = link;
     link.parent = this;
     this.length++;
 
@@ -293,13 +293,15 @@ export class Link extends EventEmitter {
   }
 
   deleteChild(link: Link) {
-    delete this.children[link.getName()];
+    const name = link.getName();
+    delete this.children[this.vol.caseSensitive ? name : name.toLowerCase()];
     this.length--;
 
     this.emit('child:delete', link, this);
   }
 
   getChild(name: string): Link | undefined {
+    if (!this.vol.caseSensitive) name = name.toLowerCase();
     if (Object.hasOwnProperty.call(this.children, name)) {
       return this.children[name];
     }

src/volume.ts

@@ -588,6 +588,8 @@ export class Volume {
   // Current number of open files.
   openFiles = 0;
 
+  caseSensitive: boolean;
+
   StatWatcher: new () => StatWatcher;
   ReadStream: new (...args) => IReadStream;
   WriteStream: new (...args) => IWriteStream;
@@ -606,9 +608,10 @@ export class Volume {
     return this.promisesApi;
   }
 
-  constructor(props = {}) {
+  constructor(props = {}, caseSensitive = true) {
     this.props = Object.assign({ Node, Link, File }, props);
 
+    this.caseSensitive = caseSensitive;
     const root = this.createLink();
     root.setNode(this.createNode(true));
 
@@ -1693,7 +1696,7 @@ export class Volume {
 
     const list: TDataOut[] = [];
     for (const name in link.children) {
-      list.push(strToEncoding(name, options.encoding));
+      list.push(strToEncoding(link.children[name]!.getName(), options.encoding));
     }
 
     if (!isWin && options.encoding !== 'buffer') list.sort();