Add support for FIREBASE_STORAGE_EMULATOR_HOST env var (#1175)

* Add support for FIREBASE_STORAGE_EMULATOR_HOST env var

* Fixes lint error

* Add test for FIREBASE_STORAGE_EMULATOR_HOST support

* Lint fix

* Minor fixes to storage tests

* Address review comments

* Address review suggestion

Co-authored-by: Samuel Bushi <ssbushi@google.com>

Author: abeisgoat

src/storage/storage.ts

@@ -48,6 +48,10 @@ export class Storage implements StorageInterface {
       });
     }
 
+    if (!process.env.STORAGE_EMULATOR_HOST && process.env.FIREBASE_STORAGE_EMULATOR_HOST) {
+      process.env.STORAGE_EMULATOR_HOST = process.env.FIREBASE_STORAGE_EMULATOR_HOST;
+    }
+    
     let storage: typeof StorageClient;
     try {
       storage = require('@google-cloud/storage').Storage;

test/unit/storage/storage.spec.ts

@@ -113,4 +113,24 @@ describe('Storage', () => {
       expect(storage.bucket('foo').name).to.equal('foo');
     });
   });
+
+  describe('Emulator mode', () => {
+    const EMULATOR_HOST = 'http://localhost:9199';
+
+    before(() => {
+      delete process.env.STORAGE_EMULATOR_HOST;
+      process.env.FIREBASE_STORAGE_EMULATOR_HOST = EMULATOR_HOST;
+    });
+
+    it('sets STORAGE_EMULATOR_HOST if FIREBASE_STORAGE_EMULATOR_HOST is set', () => {
+      new Storage(mockApp);
+      
+      expect(process.env.STORAGE_EMULATOR_HOST).to.equal(EMULATOR_HOST);
+    });
+  
+    after(() => {
+      delete process.env.STORAGE_EMULATOR_HOST;
+      delete process.env.FIREBASE_STORAGE_EMULATOR_HOST;
+    });
+  })
 });