diff --git a/packages/google-cloud-oslogin/samples/generated/v1/os_login_service.delete_posix_account.js b/packages/google-cloud-oslogin/samples/generated/v1/os_login_service.delete_posix_account.js
index 756c03d06c1b..9ffef6406c7c 100644
--- a/packages/google-cloud-oslogin/samples/generated/v1/os_login_service.delete_posix_account.js
+++ b/packages/google-cloud-oslogin/samples/generated/v1/os_login_service.delete_posix_account.js
@@ -23,6 +23,9 @@
 function main(name) {
   // [START oslogin_v1_generated_OsLoginService_DeletePosixAccount_async]
   /**
+   * This snippet has been automatically generated and should be regarded as a code template only.
+   * It will require modifications to work.
+   * It may require correct/in-range values for request initialization.
    * TODO(developer): Uncomment these variables before running the sample.
    */
   /**
diff --git a/packages/google-cloud-oslogin/samples/generated/v1/os_login_service.delete_ssh_public_key.js b/packages/google-cloud-oslogin/samples/generated/v1/os_login_service.delete_ssh_public_key.js
index 68fffcfaf18b..cf03e46e16d4 100644
--- a/packages/google-cloud-oslogin/samples/generated/v1/os_login_service.delete_ssh_public_key.js
+++ b/packages/google-cloud-oslogin/samples/generated/v1/os_login_service.delete_ssh_public_key.js
@@ -23,6 +23,9 @@
 function main(name) {
   // [START oslogin_v1_generated_OsLoginService_DeleteSshPublicKey_async]
   /**
+   * This snippet has been automatically generated and should be regarded as a code template only.
+   * It will require modifications to work.
+   * It may require correct/in-range values for request initialization.
    * TODO(developer): Uncomment these variables before running the sample.
    */
   /**
diff --git a/packages/google-cloud-oslogin/samples/generated/v1/os_login_service.get_login_profile.js b/packages/google-cloud-oslogin/samples/generated/v1/os_login_service.get_login_profile.js
index eadc1b4087da..bfe9398c9030 100644
--- a/packages/google-cloud-oslogin/samples/generated/v1/os_login_service.get_login_profile.js
+++ b/packages/google-cloud-oslogin/samples/generated/v1/os_login_service.get_login_profile.js
@@ -23,6 +23,9 @@
 function main(name) {
   // [START oslogin_v1_generated_OsLoginService_GetLoginProfile_async]
   /**
+   * This snippet has been automatically generated and should be regarded as a code template only.
+   * It will require modifications to work.
+   * It may require correct/in-range values for request initialization.
    * TODO(developer): Uncomment these variables before running the sample.
    */
   /**
diff --git a/packages/google-cloud-oslogin/samples/generated/v1/os_login_service.get_ssh_public_key.js b/packages/google-cloud-oslogin/samples/generated/v1/os_login_service.get_ssh_public_key.js
index 5238c5c17682..d95414b4f9cb 100644
--- a/packages/google-cloud-oslogin/samples/generated/v1/os_login_service.get_ssh_public_key.js
+++ b/packages/google-cloud-oslogin/samples/generated/v1/os_login_service.get_ssh_public_key.js
@@ -23,6 +23,9 @@
 function main(name) {
   // [START oslogin_v1_generated_OsLoginService_GetSshPublicKey_async]
   /**
+   * This snippet has been automatically generated and should be regarded as a code template only.
+   * It will require modifications to work.
+   * It may require correct/in-range values for request initialization.
    * TODO(developer): Uncomment these variables before running the sample.
    */
   /**
diff --git a/packages/google-cloud-oslogin/samples/generated/v1/os_login_service.import_ssh_public_key.js b/packages/google-cloud-oslogin/samples/generated/v1/os_login_service.import_ssh_public_key.js
index c058b899a31e..c6d826aa785d 100644
--- a/packages/google-cloud-oslogin/samples/generated/v1/os_login_service.import_ssh_public_key.js
+++ b/packages/google-cloud-oslogin/samples/generated/v1/os_login_service.import_ssh_public_key.js
@@ -23,6 +23,9 @@
 function main(parent) {
   // [START oslogin_v1_generated_OsLoginService_ImportSshPublicKey_async]
   /**
+   * This snippet has been automatically generated and should be regarded as a code template only.
+   * It will require modifications to work.
+   * It may require correct/in-range values for request initialization.
    * TODO(developer): Uncomment these variables before running the sample.
    */
   /**
diff --git a/packages/google-cloud-oslogin/samples/generated/v1/os_login_service.update_ssh_public_key.js b/packages/google-cloud-oslogin/samples/generated/v1/os_login_service.update_ssh_public_key.js
index 86debd03143e..a9d5dc708c61 100644
--- a/packages/google-cloud-oslogin/samples/generated/v1/os_login_service.update_ssh_public_key.js
+++ b/packages/google-cloud-oslogin/samples/generated/v1/os_login_service.update_ssh_public_key.js
@@ -23,6 +23,9 @@
 function main(name, sshPublicKey) {
   // [START oslogin_v1_generated_OsLoginService_UpdateSshPublicKey_async]
   /**
+   * This snippet has been automatically generated and should be regarded as a code template only.
+   * It will require modifications to work.
+   * It may require correct/in-range values for request initialization.
    * TODO(developer): Uncomment these variables before running the sample.
    */
   /**
diff --git a/packages/google-cloud-oslogin/samples/generated/v1/snippet_metadata.google.cloud.oslogin.v1.json b/packages/google-cloud-oslogin/samples/generated/v1/snippet_metadata.google.cloud.oslogin.v1.json
index 068af9034997..48925bdfdd46 100644
--- a/packages/google-cloud-oslogin/samples/generated/v1/snippet_metadata.google.cloud.oslogin.v1.json
+++ b/packages/google-cloud-oslogin/samples/generated/v1/snippet_metadata.google.cloud.oslogin.v1.json
@@ -22,7 +22,7 @@
             "segments": [
                 {
                     "start": 25,
-                    "end": 52,
+                    "end": 55,
                     "type": "FULL"
                 }
             ],
@@ -62,7 +62,7 @@
             "segments": [
                 {
                     "start": 25,
-                    "end": 52,
+                    "end": 55,
                     "type": "FULL"
                 }
             ],
@@ -102,7 +102,7 @@
             "segments": [
                 {
                     "start": 25,
-                    "end": 58,
+                    "end": 61,
                     "type": "FULL"
                 }
             ],
@@ -150,7 +150,7 @@
             "segments": [
                 {
                     "start": 25,
-                    "end": 52,
+                    "end": 55,
                     "type": "FULL"
                 }
             ],
@@ -190,7 +190,7 @@
             "segments": [
                 {
                     "start": 25,
-                    "end": 58,
+                    "end": 61,
                     "type": "FULL"
                 }
             ],
@@ -238,7 +238,7 @@
             "segments": [
                 {
                     "start": 25,
-                    "end": 61,
+                    "end": 64,
                     "type": "FULL"
                 }
             ],
diff --git a/packages/google-cloud-oslogin/samples/generated/v1beta/os_login_service.delete_posix_account.js b/packages/google-cloud-oslogin/samples/generated/v1beta/os_login_service.delete_posix_account.js
index 08085911a2fe..8833aa395b40 100644
--- a/packages/google-cloud-oslogin/samples/generated/v1beta/os_login_service.delete_posix_account.js
+++ b/packages/google-cloud-oslogin/samples/generated/v1beta/os_login_service.delete_posix_account.js
@@ -23,6 +23,9 @@
 function main(name) {
   // [START oslogin_v1beta_generated_OsLoginService_DeletePosixAccount_async]
   /**
+   * This snippet has been automatically generated and should be regarded as a code template only.
+   * It will require modifications to work.
+   * It may require correct/in-range values for request initialization.
    * TODO(developer): Uncomment these variables before running the sample.
    */
   /**
diff --git a/packages/google-cloud-oslogin/samples/generated/v1beta/os_login_service.delete_ssh_public_key.js b/packages/google-cloud-oslogin/samples/generated/v1beta/os_login_service.delete_ssh_public_key.js
index 621bdd467796..2dc7fdc4fa1b 100644
--- a/packages/google-cloud-oslogin/samples/generated/v1beta/os_login_service.delete_ssh_public_key.js
+++ b/packages/google-cloud-oslogin/samples/generated/v1beta/os_login_service.delete_ssh_public_key.js
@@ -23,6 +23,9 @@
 function main(name) {
   // [START oslogin_v1beta_generated_OsLoginService_DeleteSshPublicKey_async]
   /**
+   * This snippet has been automatically generated and should be regarded as a code template only.
+   * It will require modifications to work.
+   * It may require correct/in-range values for request initialization.
    * TODO(developer): Uncomment these variables before running the sample.
    */
   /**
diff --git a/packages/google-cloud-oslogin/samples/generated/v1beta/os_login_service.get_login_profile.js b/packages/google-cloud-oslogin/samples/generated/v1beta/os_login_service.get_login_profile.js
index 56121215d8d1..97028d9fcd44 100644
--- a/packages/google-cloud-oslogin/samples/generated/v1beta/os_login_service.get_login_profile.js
+++ b/packages/google-cloud-oslogin/samples/generated/v1beta/os_login_service.get_login_profile.js
@@ -23,6 +23,9 @@
 function main(name) {
   // [START oslogin_v1beta_generated_OsLoginService_GetLoginProfile_async]
   /**
+   * This snippet has been automatically generated and should be regarded as a code template only.
+   * It will require modifications to work.
+   * It may require correct/in-range values for request initialization.
    * TODO(developer): Uncomment these variables before running the sample.
    */
   /**
diff --git a/packages/google-cloud-oslogin/samples/generated/v1beta/os_login_service.get_ssh_public_key.js b/packages/google-cloud-oslogin/samples/generated/v1beta/os_login_service.get_ssh_public_key.js
index 4e89ec3ea658..7e901702ea9e 100644
--- a/packages/google-cloud-oslogin/samples/generated/v1beta/os_login_service.get_ssh_public_key.js
+++ b/packages/google-cloud-oslogin/samples/generated/v1beta/os_login_service.get_ssh_public_key.js
@@ -23,6 +23,9 @@
 function main(name) {
   // [START oslogin_v1beta_generated_OsLoginService_GetSshPublicKey_async]
   /**
+   * This snippet has been automatically generated and should be regarded as a code template only.
+   * It will require modifications to work.
+   * It may require correct/in-range values for request initialization.
    * TODO(developer): Uncomment these variables before running the sample.
    */
   /**
diff --git a/packages/google-cloud-oslogin/samples/generated/v1beta/os_login_service.import_ssh_public_key.js b/packages/google-cloud-oslogin/samples/generated/v1beta/os_login_service.import_ssh_public_key.js
index eede91051909..d1af96117a47 100644
--- a/packages/google-cloud-oslogin/samples/generated/v1beta/os_login_service.import_ssh_public_key.js
+++ b/packages/google-cloud-oslogin/samples/generated/v1beta/os_login_service.import_ssh_public_key.js
@@ -23,6 +23,9 @@
 function main(sshPublicKey) {
   // [START oslogin_v1beta_generated_OsLoginService_ImportSshPublicKey_async]
   /**
+   * This snippet has been automatically generated and should be regarded as a code template only.
+   * It will require modifications to work.
+   * It may require correct/in-range values for request initialization.
    * TODO(developer): Uncomment these variables before running the sample.
    */
   /**
diff --git a/packages/google-cloud-oslogin/samples/generated/v1beta/os_login_service.update_ssh_public_key.js b/packages/google-cloud-oslogin/samples/generated/v1beta/os_login_service.update_ssh_public_key.js
index 83b7246042d3..ce67375a1b9f 100644
--- a/packages/google-cloud-oslogin/samples/generated/v1beta/os_login_service.update_ssh_public_key.js
+++ b/packages/google-cloud-oslogin/samples/generated/v1beta/os_login_service.update_ssh_public_key.js
@@ -23,6 +23,9 @@
 function main(name, sshPublicKey) {
   // [START oslogin_v1beta_generated_OsLoginService_UpdateSshPublicKey_async]
   /**
+   * This snippet has been automatically generated and should be regarded as a code template only.
+   * It will require modifications to work.
+   * It may require correct/in-range values for request initialization.
    * TODO(developer): Uncomment these variables before running the sample.
    */
   /**
diff --git a/packages/google-cloud-oslogin/samples/generated/v1beta/snippet_metadata.google.cloud.oslogin.v1beta.json b/packages/google-cloud-oslogin/samples/generated/v1beta/snippet_metadata.google.cloud.oslogin.v1beta.json
index 896bcbe3f689..cc9106b51092 100644
--- a/packages/google-cloud-oslogin/samples/generated/v1beta/snippet_metadata.google.cloud.oslogin.v1beta.json
+++ b/packages/google-cloud-oslogin/samples/generated/v1beta/snippet_metadata.google.cloud.oslogin.v1beta.json
@@ -22,7 +22,7 @@
             "segments": [
                 {
                     "start": 25,
-                    "end": 52,
+                    "end": 55,
                     "type": "FULL"
                 }
             ],
@@ -62,7 +62,7 @@
             "segments": [
                 {
                     "start": 25,
-                    "end": 52,
+                    "end": 55,
                     "type": "FULL"
                 }
             ],
@@ -102,7 +102,7 @@
             "segments": [
                 {
                     "start": 25,
-                    "end": 58,
+                    "end": 61,
                     "type": "FULL"
                 }
             ],
@@ -150,7 +150,7 @@
             "segments": [
                 {
                     "start": 25,
-                    "end": 52,
+                    "end": 55,
                     "type": "FULL"
                 }
             ],
@@ -190,7 +190,7 @@
             "segments": [
                 {
                     "start": 25,
-                    "end": 58,
+                    "end": 61,
                     "type": "FULL"
                 }
             ],
@@ -238,7 +238,7 @@
             "segments": [
                 {
                     "start": 25,
-                    "end": 61,
+                    "end": 64,
                     "type": "FULL"
                 }
             ],
diff --git a/packages/google-cloud-oslogin/src/v1/os_login_service_client.ts b/packages/google-cloud-oslogin/src/v1/os_login_service_client.ts
index 8b047e57daaa..44722ccf7986 100644
--- a/packages/google-cloud-oslogin/src/v1/os_login_service_client.ts
+++ b/packages/google-cloud-oslogin/src/v1/os_login_service_client.ts
@@ -242,7 +242,8 @@ export class OsLoginServiceClient {
       const apiCall = this._gaxModule.createApiCall(
         callPromise,
         this._defaults[methodName],
-        descriptor
+        descriptor,
+        this._opts.fallback
       );
 
       this.innerApiCalls[methodName] = apiCall;
diff --git a/packages/google-cloud-oslogin/src/v1beta/os_login_service_client.ts b/packages/google-cloud-oslogin/src/v1beta/os_login_service_client.ts
index 7afb55ac289a..ce868a6523f4 100644
--- a/packages/google-cloud-oslogin/src/v1beta/os_login_service_client.ts
+++ b/packages/google-cloud-oslogin/src/v1beta/os_login_service_client.ts
@@ -242,7 +242,8 @@ export class OsLoginServiceClient {
       const apiCall = this._gaxModule.createApiCall(
         callPromise,
         this._defaults[methodName],
-        descriptor
+        descriptor,
+        this._opts.fallback
       );
 
       this.innerApiCalls[methodName] = apiCall;
diff --git a/packages/google-cloud-oslogin/test/gapic_os_login_service_v1.ts b/packages/google-cloud-oslogin/test/gapic_os_login_service_v1.ts
index 4961f885905a..292e8da25409 100644
--- a/packages/google-cloud-oslogin/test/gapic_os_login_service_v1.ts
+++ b/packages/google-cloud-oslogin/test/gapic_os_login_service_v1.ts
@@ -50,101 +50,103 @@ function stubSimpleCallWithCallback<ResponseType>(
 }
 
 describe('v1.OsLoginServiceClient', () => {
-  it('has servicePath', () => {
-    const servicePath =
-      osloginserviceModule.v1.OsLoginServiceClient.servicePath;
-    assert(servicePath);
-  });
-
-  it('has apiEndpoint', () => {
-    const apiEndpoint =
-      osloginserviceModule.v1.OsLoginServiceClient.apiEndpoint;
-    assert(apiEndpoint);
-  });
-
-  it('has port', () => {
-    const port = osloginserviceModule.v1.OsLoginServiceClient.port;
-    assert(port);
-    assert(typeof port === 'number');
-  });
-
-  it('should create a client with no option', () => {
-    const client = new osloginserviceModule.v1.OsLoginServiceClient();
-    assert(client);
-  });
+  describe('Common methods', () => {
+    it('has servicePath', () => {
+      const servicePath =
+        osloginserviceModule.v1.OsLoginServiceClient.servicePath;
+      assert(servicePath);
+    });
 
-  it('should create a client with gRPC fallback', () => {
-    const client = new osloginserviceModule.v1.OsLoginServiceClient({
-      fallback: true,
+    it('has apiEndpoint', () => {
+      const apiEndpoint =
+        osloginserviceModule.v1.OsLoginServiceClient.apiEndpoint;
+      assert(apiEndpoint);
     });
-    assert(client);
-  });
 
-  it('has initialize method and supports deferred initialization', async () => {
-    const client = new osloginserviceModule.v1.OsLoginServiceClient({
-      credentials: {client_email: 'bogus', private_key: 'bogus'},
-      projectId: 'bogus',
+    it('has port', () => {
+      const port = osloginserviceModule.v1.OsLoginServiceClient.port;
+      assert(port);
+      assert(typeof port === 'number');
     });
-    assert.strictEqual(client.osLoginServiceStub, undefined);
-    await client.initialize();
-    assert(client.osLoginServiceStub);
-  });
 
-  it('has close method for the initialized client', done => {
-    const client = new osloginserviceModule.v1.OsLoginServiceClient({
-      credentials: {client_email: 'bogus', private_key: 'bogus'},
-      projectId: 'bogus',
+    it('should create a client with no option', () => {
+      const client = new osloginserviceModule.v1.OsLoginServiceClient();
+      assert(client);
     });
-    client.initialize();
-    assert(client.osLoginServiceStub);
-    client.close().then(() => {
-      done();
+
+    it('should create a client with gRPC fallback', () => {
+      const client = new osloginserviceModule.v1.OsLoginServiceClient({
+        fallback: true,
+      });
+      assert(client);
     });
-  });
 
-  it('has close method for the non-initialized client', done => {
-    const client = new osloginserviceModule.v1.OsLoginServiceClient({
-      credentials: {client_email: 'bogus', private_key: 'bogus'},
-      projectId: 'bogus',
+    it('has initialize method and supports deferred initialization', async () => {
+      const client = new osloginserviceModule.v1.OsLoginServiceClient({
+        credentials: {client_email: 'bogus', private_key: 'bogus'},
+        projectId: 'bogus',
+      });
+      assert.strictEqual(client.osLoginServiceStub, undefined);
+      await client.initialize();
+      assert(client.osLoginServiceStub);
     });
-    assert.strictEqual(client.osLoginServiceStub, undefined);
-    client.close().then(() => {
-      done();
+
+    it('has close method for the initialized client', done => {
+      const client = new osloginserviceModule.v1.OsLoginServiceClient({
+        credentials: {client_email: 'bogus', private_key: 'bogus'},
+        projectId: 'bogus',
+      });
+      client.initialize();
+      assert(client.osLoginServiceStub);
+      client.close().then(() => {
+        done();
+      });
     });
-  });
 
-  it('has getProjectId method', async () => {
-    const fakeProjectId = 'fake-project-id';
-    const client = new osloginserviceModule.v1.OsLoginServiceClient({
-      credentials: {client_email: 'bogus', private_key: 'bogus'},
-      projectId: 'bogus',
+    it('has close method for the non-initialized client', done => {
+      const client = new osloginserviceModule.v1.OsLoginServiceClient({
+        credentials: {client_email: 'bogus', private_key: 'bogus'},
+        projectId: 'bogus',
+      });
+      assert.strictEqual(client.osLoginServiceStub, undefined);
+      client.close().then(() => {
+        done();
+      });
     });
-    client.auth.getProjectId = sinon.stub().resolves(fakeProjectId);
-    const result = await client.getProjectId();
-    assert.strictEqual(result, fakeProjectId);
-    assert((client.auth.getProjectId as SinonStub).calledWithExactly());
-  });
 
-  it('has getProjectId method with callback', async () => {
-    const fakeProjectId = 'fake-project-id';
-    const client = new osloginserviceModule.v1.OsLoginServiceClient({
-      credentials: {client_email: 'bogus', private_key: 'bogus'},
-      projectId: 'bogus',
+    it('has getProjectId method', async () => {
+      const fakeProjectId = 'fake-project-id';
+      const client = new osloginserviceModule.v1.OsLoginServiceClient({
+        credentials: {client_email: 'bogus', private_key: 'bogus'},
+        projectId: 'bogus',
+      });
+      client.auth.getProjectId = sinon.stub().resolves(fakeProjectId);
+      const result = await client.getProjectId();
+      assert.strictEqual(result, fakeProjectId);
+      assert((client.auth.getProjectId as SinonStub).calledWithExactly());
     });
-    client.auth.getProjectId = sinon
-      .stub()
-      .callsArgWith(0, null, fakeProjectId);
-    const promise = new Promise((resolve, reject) => {
-      client.getProjectId((err?: Error | null, projectId?: string | null) => {
-        if (err) {
-          reject(err);
-        } else {
-          resolve(projectId);
-        }
+
+    it('has getProjectId method with callback', async () => {
+      const fakeProjectId = 'fake-project-id';
+      const client = new osloginserviceModule.v1.OsLoginServiceClient({
+        credentials: {client_email: 'bogus', private_key: 'bogus'},
+        projectId: 'bogus',
+      });
+      client.auth.getProjectId = sinon
+        .stub()
+        .callsArgWith(0, null, fakeProjectId);
+      const promise = new Promise((resolve, reject) => {
+        client.getProjectId((err?: Error | null, projectId?: string | null) => {
+          if (err) {
+            reject(err);
+          } else {
+            resolve(projectId);
+          }
+        });
       });
+      const result = await promise;
+      assert.strictEqual(result, fakeProjectId);
     });
-    const result = await promise;
-    assert.strictEqual(result, fakeProjectId);
   });
 
   describe('deletePosixAccount', () => {
diff --git a/packages/google-cloud-oslogin/test/gapic_os_login_service_v1beta.ts b/packages/google-cloud-oslogin/test/gapic_os_login_service_v1beta.ts
index 1ac2e25accdd..78512e22daac 100644
--- a/packages/google-cloud-oslogin/test/gapic_os_login_service_v1beta.ts
+++ b/packages/google-cloud-oslogin/test/gapic_os_login_service_v1beta.ts
@@ -50,101 +50,103 @@ function stubSimpleCallWithCallback<ResponseType>(
 }
 
 describe('v1beta.OsLoginServiceClient', () => {
-  it('has servicePath', () => {
-    const servicePath =
-      osloginserviceModule.v1beta.OsLoginServiceClient.servicePath;
-    assert(servicePath);
-  });
-
-  it('has apiEndpoint', () => {
-    const apiEndpoint =
-      osloginserviceModule.v1beta.OsLoginServiceClient.apiEndpoint;
-    assert(apiEndpoint);
-  });
-
-  it('has port', () => {
-    const port = osloginserviceModule.v1beta.OsLoginServiceClient.port;
-    assert(port);
-    assert(typeof port === 'number');
-  });
-
-  it('should create a client with no option', () => {
-    const client = new osloginserviceModule.v1beta.OsLoginServiceClient();
-    assert(client);
-  });
+  describe('Common methods', () => {
+    it('has servicePath', () => {
+      const servicePath =
+        osloginserviceModule.v1beta.OsLoginServiceClient.servicePath;
+      assert(servicePath);
+    });
 
-  it('should create a client with gRPC fallback', () => {
-    const client = new osloginserviceModule.v1beta.OsLoginServiceClient({
-      fallback: true,
+    it('has apiEndpoint', () => {
+      const apiEndpoint =
+        osloginserviceModule.v1beta.OsLoginServiceClient.apiEndpoint;
+      assert(apiEndpoint);
     });
-    assert(client);
-  });
 
-  it('has initialize method and supports deferred initialization', async () => {
-    const client = new osloginserviceModule.v1beta.OsLoginServiceClient({
-      credentials: {client_email: 'bogus', private_key: 'bogus'},
-      projectId: 'bogus',
+    it('has port', () => {
+      const port = osloginserviceModule.v1beta.OsLoginServiceClient.port;
+      assert(port);
+      assert(typeof port === 'number');
     });
-    assert.strictEqual(client.osLoginServiceStub, undefined);
-    await client.initialize();
-    assert(client.osLoginServiceStub);
-  });
 
-  it('has close method for the initialized client', done => {
-    const client = new osloginserviceModule.v1beta.OsLoginServiceClient({
-      credentials: {client_email: 'bogus', private_key: 'bogus'},
-      projectId: 'bogus',
+    it('should create a client with no option', () => {
+      const client = new osloginserviceModule.v1beta.OsLoginServiceClient();
+      assert(client);
     });
-    client.initialize();
-    assert(client.osLoginServiceStub);
-    client.close().then(() => {
-      done();
+
+    it('should create a client with gRPC fallback', () => {
+      const client = new osloginserviceModule.v1beta.OsLoginServiceClient({
+        fallback: true,
+      });
+      assert(client);
     });
-  });
 
-  it('has close method for the non-initialized client', done => {
-    const client = new osloginserviceModule.v1beta.OsLoginServiceClient({
-      credentials: {client_email: 'bogus', private_key: 'bogus'},
-      projectId: 'bogus',
+    it('has initialize method and supports deferred initialization', async () => {
+      const client = new osloginserviceModule.v1beta.OsLoginServiceClient({
+        credentials: {client_email: 'bogus', private_key: 'bogus'},
+        projectId: 'bogus',
+      });
+      assert.strictEqual(client.osLoginServiceStub, undefined);
+      await client.initialize();
+      assert(client.osLoginServiceStub);
     });
-    assert.strictEqual(client.osLoginServiceStub, undefined);
-    client.close().then(() => {
-      done();
+
+    it('has close method for the initialized client', done => {
+      const client = new osloginserviceModule.v1beta.OsLoginServiceClient({
+        credentials: {client_email: 'bogus', private_key: 'bogus'},
+        projectId: 'bogus',
+      });
+      client.initialize();
+      assert(client.osLoginServiceStub);
+      client.close().then(() => {
+        done();
+      });
     });
-  });
 
-  it('has getProjectId method', async () => {
-    const fakeProjectId = 'fake-project-id';
-    const client = new osloginserviceModule.v1beta.OsLoginServiceClient({
-      credentials: {client_email: 'bogus', private_key: 'bogus'},
-      projectId: 'bogus',
+    it('has close method for the non-initialized client', done => {
+      const client = new osloginserviceModule.v1beta.OsLoginServiceClient({
+        credentials: {client_email: 'bogus', private_key: 'bogus'},
+        projectId: 'bogus',
+      });
+      assert.strictEqual(client.osLoginServiceStub, undefined);
+      client.close().then(() => {
+        done();
+      });
     });
-    client.auth.getProjectId = sinon.stub().resolves(fakeProjectId);
-    const result = await client.getProjectId();
-    assert.strictEqual(result, fakeProjectId);
-    assert((client.auth.getProjectId as SinonStub).calledWithExactly());
-  });
 
-  it('has getProjectId method with callback', async () => {
-    const fakeProjectId = 'fake-project-id';
-    const client = new osloginserviceModule.v1beta.OsLoginServiceClient({
-      credentials: {client_email: 'bogus', private_key: 'bogus'},
-      projectId: 'bogus',
+    it('has getProjectId method', async () => {
+      const fakeProjectId = 'fake-project-id';
+      const client = new osloginserviceModule.v1beta.OsLoginServiceClient({
+        credentials: {client_email: 'bogus', private_key: 'bogus'},
+        projectId: 'bogus',
+      });
+      client.auth.getProjectId = sinon.stub().resolves(fakeProjectId);
+      const result = await client.getProjectId();
+      assert.strictEqual(result, fakeProjectId);
+      assert((client.auth.getProjectId as SinonStub).calledWithExactly());
     });
-    client.auth.getProjectId = sinon
-      .stub()
-      .callsArgWith(0, null, fakeProjectId);
-    const promise = new Promise((resolve, reject) => {
-      client.getProjectId((err?: Error | null, projectId?: string | null) => {
-        if (err) {
-          reject(err);
-        } else {
-          resolve(projectId);
-        }
+
+    it('has getProjectId method with callback', async () => {
+      const fakeProjectId = 'fake-project-id';
+      const client = new osloginserviceModule.v1beta.OsLoginServiceClient({
+        credentials: {client_email: 'bogus', private_key: 'bogus'},
+        projectId: 'bogus',
+      });
+      client.auth.getProjectId = sinon
+        .stub()
+        .callsArgWith(0, null, fakeProjectId);
+      const promise = new Promise((resolve, reject) => {
+        client.getProjectId((err?: Error | null, projectId?: string | null) => {
+          if (err) {
+            reject(err);
+          } else {
+            resolve(projectId);
+          }
+        });
       });
+      const result = await promise;
+      assert.strictEqual(result, fakeProjectId);
     });
-    const result = await promise;
-    assert.strictEqual(result, fakeProjectId);
   });
 
   describe('deletePosixAccount', () => {