chore: Add pagination showcase tests (#1635)

* chore: Add pagination test for httpjson

* chore: Fix comments

* chore: Add pageToken index as offset

* chore: Clean up pagination tests

* chore: Add grpc test cases

* chore: Fix test comments

* chore: Address PR comments

* chore: Address PR comments

* chore: Remove expand showcase tests

* chore: Use larger pagetoken value

showcase/gapic-showcase/src/test/java/com/google/showcase/v1beta1/it/ITPagination.java

@@ -0,0 +1,147 @@
+/*
+ * Copyright 2023 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.showcase.v1beta1.it;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import com.google.showcase.v1beta1.EchoClient;
+import com.google.showcase.v1beta1.EchoResponse;
+import com.google.showcase.v1beta1.PagedExpandRequest;
+import com.google.showcase.v1beta1.it.util.TestClientInitializer;
+import java.util.concurrent.TimeUnit;
+import org.junit.AfterClass;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+public class ITPagination {
+
+  private static EchoClient grpcClient;
+  private static EchoClient httpjsonClient;
+
+  @BeforeClass
+  public static void createClients() throws Exception {
+    // Create gRPC Echo Client
+    grpcClient = TestClientInitializer.createGrpcEchoClient();
+    // Create Http JSON Echo Client
+    httpjsonClient = TestClientInitializer.createHttpJsonEchoClient();
+  }
+
+  @AfterClass
+  public static void destroyClients() throws InterruptedException {
+    grpcClient.close();
+    httpjsonClient.close();
+
+    grpcClient.awaitTermination(TestClientInitializer.AWAIT_TERMINATION_SECONDS, TimeUnit.SECONDS);
+    httpjsonClient.awaitTermination(
+        TestClientInitializer.AWAIT_TERMINATION_SECONDS, TimeUnit.SECONDS);
+  }
+
+  // This tests that pagination returns the correct number of pages + responses and that
+  // the content is correct.
+  //
+  // The pageToken is where the streaming responses come back from and the page size denotes
+  // how many of the responses come back together (in a page). i.e for PageSize = 2 and
+  // PageToken = 3, see below:
+  //         | A | Series  | Of  | Words | That  | Will  | Be  | Sent  | Back  | One | By  | One
+  // Page #  | - | -       | -   | 1     | 1     | 2     | 2   | 3     | 3     | 4   | 4   | 5
+  // Token # | 0 | 1       | 2   | 3     | 4     | 5     | 6   | 7     | 8     | 9   | 10  | 11
+  @Test
+  public void testPagedExpandWithTokenGrpc() {
+    int pageSize = 2;
+    int pageToken = 3;
+    String content = "A series of words that will be sent back one by one";
+    int contentLength = content.split(" ").length;
+
+    EchoClient.PagedExpandPagedResponse pagedExpandPagedResponse =
+        grpcClient.pagedExpand(
+            PagedExpandRequest.newBuilder()
+                .setContent(content)
+                .setPageSize(pageSize)
+                .setPageToken(String.valueOf(pageToken))
+                .build());
+
+    String[] expected = content.split(" ");
+    int numExpectedPages = ((contentLength - pageToken) / pageSize);
+    // If the responses can't be evenly split into pages, then the extra responses
+    // will go to an additional page
+    if ((contentLength - pageToken) % pageSize != 0) {
+      numExpectedPages++;
+    }
+    int numExpectedResponses = contentLength - pageToken;
+
+    validatePagedResponses(
+        pagedExpandPagedResponse, expected, pageToken, numExpectedResponses, numExpectedPages);
+  }
+
+  // This tests that pagination returns the correct number of pages + responses and that
+  // the content is correct.
+  //
+  // The pageToken is where the streaming responses come back from and the page size denotes
+  // how many of the responses come back together (in a page). i.e for PageSize = 2 and
+  // PageToken = 3, see below:
+  //         | A | Series  | Of  | Words | That  | Will  | Be  | Sent  | Back  | One | By  | One
+  // Page #  | - | -       | -   | 1     | 1     | 2     | 2   | 3     | 3     | 4   | 4   | 5
+  // Token # | 0 | 1       | 2   | 3     | 4     | 5     | 6   | 7     | 8     | 9   | 10  | 11
+  @Test
+  public void testPagedExpandWithTokenHttpJson() {
+    int pageSize = 2;
+    int pageToken = 3;
+    String content = "A series of words that will be sent back one by one";
+    int contentLength = content.split(" ").length;
+
+    EchoClient.PagedExpandPagedResponse pagedExpandPagedResponse =
+        httpjsonClient.pagedExpand(
+            PagedExpandRequest.newBuilder()
+                .setContent(content)
+                .setPageSize(pageSize)
+                .setPageToken(String.valueOf(pageToken))
+                .build());
+
+    String[] expected = content.split(" ");
+    int numExpectedPages = ((contentLength - pageToken) / pageSize);
+    // If the responses can't be evenly split into pages, then the extra responses
+    // will go to an additional page
+    if ((contentLength - pageToken) % pageSize != 0) {
+      numExpectedPages++;
+    }
+    int numExpectedResponses = contentLength - pageToken;
+
+    validatePagedResponses(
+        pagedExpandPagedResponse, expected, pageToken, numExpectedResponses, numExpectedPages);
+  }
+
+  private void validatePagedResponses(
+      EchoClient.PagedExpandPagedResponse pagedExpandPagedResponse,
+      String[] expected,
+      int pageToken,
+      int numExpectedResponses,
+      int numExpectedPages) {
+    int numResponses = 0;
+    int numPages = 0;
+    for (EchoClient.PagedExpandPage page : pagedExpandPagedResponse.iteratePages()) {
+      for (EchoResponse echoResponse : page.getValues()) {
+        // Add pageToken as offset to the expected array to start indexing at the pageToken
+        assertThat(echoResponse.getContent()).isEqualTo(expected[numResponses + pageToken]);
+        numResponses++;
+      }
+      numPages++;
+    }
+
+    assertThat(numPages).isEqualTo(numExpectedPages);
+    assertThat(numResponses).isEqualTo(numExpectedResponses);
+  }
+}