fix: sort modules in debugger delta patcher to match source map order (…

…react-native-community#279)

Summary:
---------

Context: facebook/metro#380, facebook/react-native#23955

Fixes a discrepancy between the order of modules in the source map and in the actual bundle, caused by a change in Metro (see details in facebook/metro#380 (comment)). Consequently fixes React Native remote JS debugging.

Test Plan:
----------

1. Made the same change in my checkout of the repro code from facebook/metro#380 and verified debugging works.
2. Added unit tests.

packages/cli/src/commands/server/debugger-ui/DeltaPatcher.js

@@ -119,7 +119,10 @@
     getAllModules() {
       return [].concat(
         [this._lastBundle.pre],
-        Array.from(this._lastBundle.modules.values()),
+        // Sort modules so they match the source map emitted by Metro >= 0.51.0
+        Array.from(this._lastBundle.modules.entries())
+          .sort(([id1], [id2]) => id1 - id2)
+          .map(([id, contents]) => contents),
         [this._lastBundle.post],
       );
     }

packages/cli/src/commands/server/debugger-ui/__tests__/DeltaPatcher-test.js

@@ -108,4 +108,55 @@ describe('DeltaPatcher', () => {
     expect(dp.getLastNumModifiedFiles()).toBe(2);
     expect(dp.getAllModules()).toEqual(['pre2', '__d(4);', '__d(5);', 'post2']);
   });
+
+  it('should sort modules after receiving an unsorted base bundle', () => {
+    const dp = new window.DeltaPatcher();
+    global.Date = jest.fn();
+    dp.applyDelta({
+      base: true,
+      revisionId: 'rev0',
+      pre: 'pre0',
+      post: 'post0',
+      modules: [[2, '__d(2);'], [3, '__d(3);'], [0, '__d(0);'], [1, '__d(1);']],
+    });
+    expect(dp.getLastRevisionId()).toBe('rev0');
+    expect(dp.getLastModifiedDate()).toBe(global.Date.mock.instances[0]);
+    expect(dp.getLastNumModifiedFiles()).toBe(4);
+    expect(dp.getAllModules()).toEqual([
+      'pre0',
+      '__d(0);',
+      '__d(1);',
+      '__d(2);',
+      '__d(3);',
+      'post0',
+    ]);
+  });
+
+  it('should sort modules after receiving an unsorted delta bundle', () => {
+    const dp = new window.DeltaPatcher();
+    dp.applyDelta({
+      base: true,
+      revisionId: 'rev0',
+      pre: 'pre0',
+      post: 'post0',
+      modules: [[2, '__d(2);'], [1, '__d(1);'], [0, '__d(0);']],
+    });
+    global.Date = jest.fn();
+    dp.applyDelta({
+      base: false,
+      revisionId: 'rev1',
+      modules: [[3, '__d(3);'], [1, '__d(1.1);']],
+      deleted: [0],
+    });
+    expect(dp.getLastRevisionId()).toBe('rev1');
+    expect(dp.getLastModifiedDate()).toBe(global.Date.mock.instances[0]);
+    expect(dp.getLastNumModifiedFiles()).toBe(3);
+    expect(dp.getAllModules()).toEqual([
+      'pre0',
+      '__d(1.1);',
+      '__d(2);',
+      '__d(3);',
+      'post0',
+    ]);
+  });
 });