feat: Adds abandonInstances to InstanceGroupManger API (#306)

* Adds abandonInstances to InstanceGroupManger API

* Changes callbacks to fat arrow syntax

* Updated callbacks in all functions, not just abandonInstances.
* Removed extraneous `self = this`.

packages/google-cloud-compute/src/instance-group-manager.js

@@ -153,6 +153,61 @@ class InstanceGroupManager extends common.ServiceObject {
      */
     this.name = name;
   }
+  /**
+   * Flags the specified instances to be removed from the managed instance group.
+   * @see [InstanceGroupManagers: abandonInstances API Documentation]{@link https://cloud.google.com/compute/docs/reference/v1/instanceGroupManagers/abandonInstances}
+   * @param {VM|VM[]} vms - VM instances to abandon from
+   *     this instance group manager.
+   * @param {function} callback - The callback function.
+   * @param {?error} callback.err - An error returned while making this request.
+   * @param {Operation} callback.operation - An operation object
+   *     that can be used to check the status of the request.
+   * @param {object} callback.apiResponse - The full API response.
+   *
+   * @example
+   * const Compute = require('@google-cloud/compute');
+   * const compute = new Compute();
+   * const zone = compute.zone('us-central1-a');
+   * const instanceGroupManager = zone.instanceGroupManager('web-servers');
+   *
+   * const vms = [
+   *   gce.zone('us-central1-a').vm('http-server'),
+   *   gce.zone('us-central1-a').vm('https-server')
+   * ];
+   *
+   * instanceGroupManager.abandonInstances(vms, function(err, operation, apiResponse) {
+   *   // `operation` is an Operation object that can be used to check the status
+   *   // of the request.
+   * });
+   *
+   * //-
+   * // If the callback is omitted, we'll return a Promise.
+   * //-
+   * instanceGroupManager.abandonInstances(vms).then(function(data) {
+   *   const operation = data[0];
+   *   const apiResponse = data[1];
+   * });
+   */
+  abandonInstances(vms, callback) {
+    this.request(
+      {
+        method: 'POST',
+        uri: '/abandonInstances',
+        json: {
+          instances: arrify(vms).map(vm => vm.url),
+        },
+      },
+      (err, resp) => {
+        if (err) {
+          callback(err, null, resp);
+          return;
+        }
+        const operation = this.zone.operation(resp.name);
+        operation.metadata = resp;
+        callback(null, operation, resp);
+      }
+    );
+  }
   /**
    * Flags the specified instances in the managed instance group for immediate deletion.
    * @see [InstanceGroupManagers: deleteInstances API Documentation]{@link https://cloud.google.com/compute/docs/reference/v1/instanceGroupManagers/deleteInstances}
@@ -189,23 +244,20 @@ class InstanceGroupManager extends common.ServiceObject {
    * });
    */
   deleteInstances(vms, callback) {
-    const self = this;
     this.request(
       {
         method: 'POST',
         uri: '/deleteInstances',
         json: {
-          instances: arrify(vms).map(function(vm) {
-            return vm.url;
-          }),
+          instances: arrify(vms).map(vm => vm.url),
         },
       },
-      function(err, resp) {
+      (err, resp) => {
         if (err) {
           callback(err, null, resp);
           return;
         }
-        const operation = self.zone.operation(resp.name);
+        const operation = this.zone.operation(resp.name);
         operation.metadata = resp;
         callback(null, operation, resp);
       }
@@ -269,7 +321,6 @@ class InstanceGroupManager extends common.ServiceObject {
    * });
    */
   getManagedInstances(options, callback) {
-    const self = this;
     if (is.fn(options)) {
       callback = options;
       options = {};
@@ -281,7 +332,7 @@ class InstanceGroupManager extends common.ServiceObject {
         uri: '/listManagedInstances',
         qs: options,
       },
-      function(err, resp) {
+      (err, resp) => {
         if (err) {
           callback(err, null, null, resp);
           return;
@@ -292,8 +343,8 @@ class InstanceGroupManager extends common.ServiceObject {
             pageToken: resp.nextPageToken,
           });
         }
-        const vms = arrify(resp.managedInstances).map(function(vm) {
-          const vmInstance = self.zone.vm(vm.instance);
+        const vms = arrify(resp.managedInstances).map(vm => {
+          const vmInstance = this.zone.vm(vm.instance);
           vmInstance.metadata = vm;
           return vmInstance;
         });
@@ -333,19 +384,18 @@ class InstanceGroupManager extends common.ServiceObject {
    * });
    */
   resize(size, callback) {
-    const self = this;
     this.request(
       {
         method: 'POST',
         uri: '/resize',
         qs: {size: size},
       },
-      function(err, resp) {
+      (err, resp) => {
         if (err) {
           callback(err, null, resp);
           return;
         }
-        const operation = self.zone.operation(resp.name);
+        const operation = this.zone.operation(resp.name);
         operation.metadata = resp;
         callback(null, operation, resp);
       }

packages/google-cloud-compute/test/instance-group-manager.js

@@ -93,6 +93,81 @@ describe('InstanceGroupManager', function() {
     });
   });
 
+  describe('abandonInstances', function() {
+    const VMS = [{url: 'vm-url'}, {url: 'vm-url-2'}];
+
+    it('should make the correct API request', function(done) {
+      instanceGroupManager.request = function(reqOpts) {
+        assert.strictEqual(reqOpts.method, 'POST');
+        assert.strictEqual(reqOpts.uri, '/abandonInstances');
+        assert.deepStrictEqual(reqOpts.json, {
+          instances: VMS.map(function(vm) {
+            return vm.url;
+          }),
+        });
+
+        done();
+      };
+
+      instanceGroupManager.abandonInstances(VMS, assert.ifError);
+    });
+
+    describe('error', function() {
+      const apiResponse = {};
+      const error = new Error('Error.');
+
+      beforeEach(function() {
+        instanceGroupManager.request = function(reqOpts, callback) {
+          callback(error, apiResponse);
+        };
+      });
+
+      it('should return an error and API response', function(done) {
+        instanceGroupManager.abandonInstances(VMS, function(
+          err,
+          operation,
+          apiResponse_
+        ) {
+          assert.strictEqual(err, error);
+          assert.strictEqual(operation, null);
+          assert.strictEqual(apiResponse_, apiResponse);
+          done();
+        });
+      });
+    });
+
+    describe('success', function() {
+      const apiResponse = {name: 'op-name'};
+
+      beforeEach(function() {
+        instanceGroupManager.request = function(reqOpts, callback) {
+          callback(null, apiResponse);
+        };
+      });
+
+      it('should return an Operation and API response', function(done) {
+        const operation = {};
+
+        instanceGroupManager.zone.operation = function(name) {
+          assert.strictEqual(name, apiResponse.name);
+          return operation;
+        };
+
+        instanceGroupManager.abandonInstances(VMS, function(
+          err,
+          operation_,
+          apiResponse_
+        ) {
+          assert.ifError(err);
+          assert.strictEqual(operation_, operation);
+          assert.strictEqual(operation.metadata, apiResponse);
+          assert.strictEqual(apiResponse_, apiResponse);
+          done();
+        });
+      });
+    });
+  });
+
   describe('deleteInstances', function() {
     const VMS = [{url: 'vm-url'}, {url: 'vm-url-2'}];