fix: don't modify passed in options (#1895)

* fix: don't modify passed in options

* 🦉 Updates from OwlBot post-processor

See https://github.com/googleapis/repo-automation-bots/blob/main/packages/owl-bot/README.md

* added test

* 🦉 Updates from OwlBot post-processor

See https://github.com/googleapis/repo-automation-bots/blob/main/packages/owl-bot/README.md

Co-authored-by: Owl Bot <gcf-owl-bot[bot]@users.noreply.github.com>

Author: shaffeeullah

src/file.ts

@@ -1835,7 +1835,7 @@ class File extends ServiceObject<File> {
    */
   // eslint-disable-next-line @typescript-eslint/no-explicit-any
   createWriteStream(options: CreateWriteStreamOptions = {}): Writable {
-    options = Object.assign({metadata: {}}, options);
+    options = extend(true, {metadata: {}}, options);
 
     if (options.contentType) {
       options.metadata.contentType = options.contentType;
@@ -3951,7 +3951,8 @@ class File extends ServiceObject<File> {
     dup: Duplexify,
     options: CreateResumableUploadOptions
   ): void {
-    options = Object.assign(
+    options = extend(
+      true,
       {
         metadata: {},
       },
@@ -4019,7 +4020,8 @@ class File extends ServiceObject<File> {
    * @private
    */
   startSimpleUpload_(dup: Duplexify, options?: CreateWriteStreamOptions): void {
-    options = Object.assign(
+    options = extend(
+      true,
       {
         metadata: {},
       },

test/file.ts

@@ -2019,7 +2019,6 @@ describe('File', () => {
       const writable = file.createWriteStream(options);
 
       file.startSimpleUpload_ = (stream: {}, options_: {}) => {
-        assert.deepStrictEqual(options_, options);
         done();
       };
 
@@ -2034,7 +2033,6 @@ describe('File', () => {
       const writable = file.createWriteStream(options);
 
       file.startResumableUpload_ = (stream: {}, options_: {}) => {
-        assert.deepStrictEqual(options_, options);
         done();
       };
 
@@ -2050,7 +2048,6 @@ describe('File', () => {
       const writable = file.createWriteStream(options);
 
       file.startResumableUpload_ = (stream: {}, options_: {}) => {
-        assert.deepStrictEqual(options_, options);
         done();
       };
 
@@ -2170,7 +2167,6 @@ describe('File', () => {
         });
 
         file.startSimpleUpload_ = (stream: Stream, _options: {}) => {
-          assert.deepStrictEqual(_options, options);
           done();
         };
 
@@ -2185,7 +2181,6 @@ describe('File', () => {
 
       // eslint-disable-next-line @typescript-eslint/no-explicit-any
       file.startResumableUpload_ = (stream: {}, options: any) => {
-        assert.deepStrictEqual(options.metadata, METADATA);
         done();
       };
 
@@ -2226,6 +2221,19 @@ describe('File', () => {
       writable.write('data');
     });
 
+    it('should not overwrite passed in options', done => {
+      const emptyObject = {};
+      const writable = file.createWriteStream(emptyObject);
+      // eslint-disable-next-line @typescript-eslint/no-explicit-any
+      file.startResumableUpload_ = (stream: {}, options: any) => {
+        assert.strictEqual(options.metadata.contentType, 'image/png');
+        assert.deepStrictEqual(emptyObject, {});
+        done();
+      };
+
+      writable.write('data');
+    });
+
     it('should not set a contentType if mime lookup failed', done => {
       const file = new File('file-without-ext');
       const writable = file.createWriteStream();
@@ -4829,7 +4837,7 @@ describe('File', () => {
             assert.strictEqual(opts.file, file.name);
             assert.strictEqual(opts.generation, file.generation);
             assert.strictEqual(opts.key, file.encryptionKey);
-            assert.strictEqual(opts.metadata, options.metadata);
+            assert.deepStrictEqual(opts.metadata, options.metadata);
             assert.strictEqual(opts.offset, options.offset);
             assert.strictEqual(opts.predefinedAcl, options.predefinedAcl);
             assert.strictEqual(opts.private, options.private);
@@ -4992,7 +5000,7 @@ describe('File', () => {
 
       // eslint-disable-next-line @typescript-eslint/no-explicit-any
       makeWritableStreamOverride = (stream: {}, options_: any) => {
-        assert.strictEqual(options_.metadata, options.metadata);
+        assert.deepStrictEqual(options_.metadata, options.metadata);
         assert.deepStrictEqual(options_.request, {
           qs: {
             name: file.name,