Fix the parsing of the HMR legacy URLs

Reviewed By: mjesun

Differential Revision: D13060504

fbshipit-source-id: 54cfda78eae335d6df47217ed12ccc3a656f3e4a

Author: rafeca

packages/metro/src/HmrServer/__tests__/HmrServer-test.js

@@ -12,9 +12,10 @@
 const HmrServer = require('..');
 
 const getGraphId = require('../../lib/getGraphId');
+
 jest.mock('../../lib/transformHelpers', () => ({
   getResolveDependencyFn: () => (from, to) =>
-    `${from.replace(/\.$/, '')}${to}.js`,
+    `${require('path').resolve(from, to)}.js`,
 }));
 
 describe('HmrServer', () => {

packages/metro/src/lib/__tests__/parseOptionsFromUrl-test.js

@@ -105,6 +105,12 @@ describe('parseOptionsFromUrl', () => {
     ).toMatchObject({hot: true});
   });
 
+  it('retrieves stuff from HMR urls', () => {
+    expect(
+      parseOptionsFromUrl('my/bundle.bundle', new Set([])).options,
+    ).toMatchObject({entryFile: './my/bundle'});
+  });
+
   describe.each([
     ['dev', true],
     ['minify', false],

packages/metro/src/lib/parseOptionsFromUrl.js

@@ -52,7 +52,7 @@ function parseOptionsFromUrl(
   // Backwards compatibility. Options used to be as added as '.' to the
   // entry module name. We can safely remove these options.
   const entryFileRelativeToProjectRoot = pathname
-    .replace(/^\//, './') // We want to produce a relative path to project root
+    .replace(/^(?:\.?\/)?/, './') // We want to produce a relative path to project root
     .split('.')
     .filter(part => {
       if (part === 'map') {