fix(app): Add more detailed warning for duplicate app error (#10182)

.changeset/eleven-pillows-notice.md

@@ -0,0 +1,5 @@
+---
+'@firebase/app': patch
+---
+
+Add more detailed error when `initializeApp()` is called a second time with different options or config, that prints the different options or config.

packages/app/src/api.test.ts

@@ -102,7 +102,7 @@ describe('API tests', () => {
         initializeApp({
           apiKey: 'test2'
         })
-      ).throws(/\[DEFAULT\].*exists/i);
+      ).throws(/\[DEFAULT\].*exists with different options.*test1.*test2/i);
     });
 
     it('throws when creating duplicate named Apps with different options', () => {
@@ -120,7 +120,7 @@ describe('API tests', () => {
           },
           appName
         )
-      ).throws(/'MyApp'.*exists/i);
+      ).throws(/'MyApp'.*exists with different options.*test1.*test2/i);
     });
 
     it('throws when creating duplicate DEFAULT Apps with different config values', () => {
@@ -137,7 +137,7 @@ describe('API tests', () => {
           },
           { automaticDataCollectionEnabled: true }
         )
-      ).throws(/\[DEFAULT\].*exists/i);
+      ).throws(/\[DEFAULT\].*exists with different config.*false.*true/i);
     });
 
     it('throws when creating duplicate named Apps with different config values', () => {
@@ -155,7 +155,7 @@ describe('API tests', () => {
           },
           { name: appName, automaticDataCollectionEnabled: true }
         )
-      ).throws(/'MyApp'.*exists/i);
+      ).throws(/'MyApp'.*exists with different config.*false.*true/i);
     });
 
     it('takes an object as the second parameter to create named App', () => {
@@ -479,7 +479,7 @@ describe('API tests', () => {
               expect(count).to.equal(0);
               count++;
             }
-          } as _FirebaseService),
+          }) as _FirebaseService,
         ComponentType.PUBLIC
       );
       _registerComponent(comp1);

packages/app/src/api.ts

@@ -171,13 +171,22 @@ export function initializeApp(
   const existingApp = _apps.get(name) as FirebaseAppImpl;
   if (existingApp) {
     // return the existing app if options and config deep equal the ones in the existing app.
-    if (
-      deepEqual(options, existingApp.options) &&
-      deepEqual(config, existingApp.config)
-    ) {
-      return existingApp;
+    if (!deepEqual(options, existingApp.options)) {
+      throw ERROR_FACTORY.create(AppError.DUPLICATE_APP, {
+        appName: name,
+        mismatchedParam: 'options',
+        oldValue: JSON.stringify(existingApp.options),
+        newValue: JSON.stringify(options)
+      });
+    } else if (!deepEqual(config, existingApp.config)) {
+      throw ERROR_FACTORY.create(AppError.DUPLICATE_APP, {
+        appName: name,
+        mismatchedParam: 'config',
+        oldValue: JSON.stringify(existingApp.config),
+        newValue: JSON.stringify(config)
+      });
     } else {
-      throw ERROR_FACTORY.create(AppError.DUPLICATE_APP, { appName: name });
+      return existingApp;
     }
   }
 

packages/app/src/errors.ts

@@ -40,7 +40,8 @@ const ERRORS: ErrorMap<AppError> = {
     'call initializeApp() first',
   [AppError.BAD_APP_NAME]: "Illegal App name: '{$appName}'",
   [AppError.DUPLICATE_APP]:
-    "Firebase App named '{$appName}' already exists with different options or config",
+    "Firebase App named '{$appName}' already exists with different {$mismatchedParam}." +
+    " Existing: '{$oldValue}'. New: '{$newValue}'.",
   [AppError.APP_DELETED]: "Firebase App named '{$appName}' already deleted",
   [AppError.SERVER_APP_DELETED]: 'Firebase Server App has been deleted',
   [AppError.NO_OPTIONS]:
@@ -67,7 +68,12 @@ const ERRORS: ErrorMap<AppError> = {
 interface ErrorParams {
   [AppError.NO_APP]: { appName: string };
   [AppError.BAD_APP_NAME]: { appName: string };
-  [AppError.DUPLICATE_APP]: { appName: string };
+  [AppError.DUPLICATE_APP]: {
+    appName: string;
+    mismatchedParam: string;
+    oldValue: string;
+    newValue: string;
+  };
   [AppError.APP_DELETED]: { appName: string };
   [AppError.INVALID_APP_ARGUMENT]: { appName: string };
   [AppError.IDB_OPEN]: { originalErrorMessage?: string };