[MINOR] Quickstart.generateUpdates method add check

hudi-spark-datasource/hudi-spark/src/main/java/org/apache/hudi/QuickstartUtils.java

@@ -23,6 +23,7 @@
 import org.apache.hudi.common.model.HoodieRecord;
 import org.apache.hudi.common.model.OverwriteWithLatestAvroPayload;
 import org.apache.hudi.common.util.Option;
+import org.apache.hudi.exception.HoodieException;
 import org.apache.hudi.exception.HoodieIOException;
 
 import org.apache.avro.Schema;
@@ -31,7 +32,6 @@
 import org.apache.spark.sql.Row;
 
 import java.io.IOException;
-import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.HashMap;
 import java.util.List;
@@ -175,15 +175,18 @@ public HoodieRecord generateUpdateRecord(HoodieKey key, String randomString) thr
      * @param n Number of updates (including dups)
      * @return list of hoodie record updates
      */
-    public List<HoodieRecord> generateUpdates(Integer n) throws IOException {
-      String randomString = generateRandomString();
-      List<HoodieRecord> updates = new ArrayList<>();
-      for (int i = 0; i < n; i++) {
-        HoodieKey key = existingKeys.get(rand.nextInt(numExistingKeys));
-        HoodieRecord record = generateUpdateRecord(key, randomString);
-        updates.add(record);
+    public List<HoodieRecord> generateUpdates(Integer n) {
+      if (numExistingKeys == 0) {
+        throw new HoodieException("Data must have been written before performing the update operation");
       }
-      return updates;
+      String randomString = generateRandomString();
+      return IntStream.range(0, n).boxed().map(x -> {
+        try {
+          return generateUpdateRecord(existingKeys.get(rand.nextInt(numExistingKeys)), randomString);
+        } catch (IOException e) {
+          throw new HoodieIOException(e.getMessage(), e);
+        }
+      }).collect(Collectors.toList());
     }
 
     /**

hudi-spark-datasource/hudi-spark/src/test/java/org/apache/hudi/TestQuickstartUtils.java

@@ -0,0 +1,45 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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
+ *
+ *      http://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 org.apache.hudi;
+
+import org.apache.hudi.exception.HoodieException;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.mockito.junit.jupiter.MockitoExtension;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+@ExtendWith(MockitoExtension.class)
+public class TestQuickstartUtils {
+
+  @Test
+  public void testGenerateUpdates() throws Exception {
+    QuickstartUtils.DataGenerator dataGenerator = new QuickstartUtils.DataGenerator();
+
+    //Call generateUpdates directly then throws HoodieException
+    assertEquals(Assertions.assertThrows(HoodieException.class, () -> {
+      dataGenerator.generateUpdates(10);
+    }).getMessage(), "Data must have been written before performing the update operation");
+
+    //Execute generateInserts before executing generateUpdates then no exception
+    assertEquals(dataGenerator.generateInserts(10).size(), 10);
+    assertEquals(dataGenerator.generateUpdates(10).size(), 10);
+  }
+}