feat: rewrite root paths

.gitignore

@@ -1,8 +1,8 @@
 .idea
 node_modules
 /.idea
-.nyc_output
-coverage
+/.nyc_output/
+/coverage/
 package-lock.json
 yarn.lock
 /lib/

src/__tests__/index.test.ts

@@ -8,6 +8,7 @@ describe('rewrite(fs, rewrites)', () => {
         const lfs = link(vol, ['/lol', '/foo']);
         expect(lfs.readFileSync('/lol', 'utf8')).toBe('bar');
     });
+
     it('Each path step should be rewritten completely', () => {
         const vol = Volume.fromJSON({'/foo/bar': 'hello'});
         const lfs = link(vol, ['/lol', '/fo']);
@@ -19,6 +20,7 @@ describe('rewrite(fs, rewrites)', () => {
             expect(err.code).toBe('ENOENT');
         }
     });
+
     it('Invalid rewrite routes argument throws', () => {
         const vol = Volume.fromJSON({'/foo/bar': 'hello'});
         try {
@@ -28,6 +30,7 @@ describe('rewrite(fs, rewrites)', () => {
             expect(err.message === 'not_this').toBe(false);
         }
     });
+
     it('Invalid path argument gets proxied', () => {
         const vol = Volume.fromJSON({'/foo/bar': 'hello'});
         try {
@@ -38,4 +41,22 @@ describe('rewrite(fs, rewrites)', () => {
             expect(err.code).toBe('EBADF');
         }
     });
+
+    it('rewrites multi-step paths', () => {
+        const vol = Volume.fromJSON({
+            '/1/2/3/4': 'foo'
+        });
+        const lfs = link(vol, ['/lol', '/1/2/3']);
+
+        expect(lfs.readFileSync('/lol/4', 'utf8')).toBe('foo');
+    });
+
+    it('rewrites root path', () => {
+        const vol = Volume.fromJSON({
+            '/1/2/3/4': 'foo'
+        });
+        const lfs = link(vol, ['/', '/1/2/3']);
+
+        expect(lfs.readFileSync('/4', 'utf8')).toBe('foo');
+    });
 });

src/index.ts

@@ -1,4 +1,4 @@
-import {resolve} from 'path';
+import {resolve, sep} from 'path';
 
 
 export const props = [
@@ -127,10 +127,18 @@ export function link(fs, rewrites: string[] | string[][]): any {
             let filename = resolve(String(path));
             for(const [from, to] of rews) {
                 if(filename.indexOf(from) === 0) {
-                    // filename = filename.replace(from, to);
-                    const regex = new RegExp('^(' + from.replace(/\\/g, '\\\\') + ')(\\\\|\/|$)');
-                    filename = filename.replace(regex, (match, p1, p2, off, str) => to + p2);
-                }
+                    const rootRegex = /(?:^[a-zA-Z]:\\$)|(?:^\/$)/; // C:\ vs /
+                    const isRoot = from.match(rootRegex);
+                    const baseRegex = '^(' + from.replace(/\\/g, '\\\\') + ')';
+
+                    if(isRoot) {
+                      const regex = new RegExp(baseRegex);
+                      filename = filename.replace(regex, () => to + sep);
+                    } else {
+                      const regex = new RegExp(baseRegex + '(\\\\|\/|$)');
+                      filename = filename.replace(regex, (match, p1, p2) => to + p2);
+                    }
+                  }
             }
 
             args[0] = filename;