fix: do not override user-provided options (#463)

src/index.js

@@ -18,6 +18,7 @@
 
 const arrify = require('arrify');
 const common = require('@google-cloud/common');
+const extend = require('extend');
 const format = require('string-format-obj');
 const is = require('is');
 const {promisifyAll} = require('@google-cloud/promisify');
@@ -82,7 +83,13 @@ const Image = require('./image.js');
  */
 class Compute extends common.Service {
   constructor(options = {}) {
-    options.apiEndpoint = options.apiEndpoint || 'compute.googleapis.com';
+    options = extend(
+      true,
+      {
+        apiEndpoint: 'compute.googleapis.com',
+      },
+      options
+    );
     const config = {
       apiEndpoint: options.apiEndpoint,
       baseUrl: `https://${options.apiEndpoint}/compute/v1`,

test/index.js

@@ -211,7 +211,9 @@ describe('Compute', () => {
 
       const calledWith = compute.calledWith_[0];
 
-      const baseUrl = 'https://compute.googleapis.com/compute/v1';
+      const apiEndpoint = 'compute.googleapis.com';
+      const baseUrl = `https://${apiEndpoint}/compute/v1`;
+      assert.strictEqual(calledWith.apiEndpoint, apiEndpoint);
       assert.strictEqual(calledWith.baseUrl, baseUrl);
       assert.deepStrictEqual(calledWith.scopes, [
         'https://www.googleapis.com/auth/compute',
@@ -242,6 +244,24 @@ describe('Compute', () => {
       assert.strictEqual(compute.getZonesStream, 'getZones');
     });
 
+    it('should allow overriding the API endpoint', () => {
+      const apiEndpoint = 'custom.endpoint.com';
+      const compute = new Compute({apiEndpoint});
+      const calledWith = compute.calledWith_[0];
+
+      assert.strictEqual(calledWith.apiEndpoint, apiEndpoint);
+      assert.strictEqual(
+        calledWith.baseUrl,
+        `https://${apiEndpoint}/compute/v1`
+      );
+    });
+
+    it('should localize the poll interval', () => {
+      const pollIntervalMs = 9;
+      const compute = new Compute({pollIntervalMs});
+      assert.strictEqual(compute.pollIntervalMs, pollIntervalMs);
+    });
+
     it('should promisify all the things', () => {
       assert(promisified);
     });