DATAREDIS-417 - Add failing tests for ScanCursor throwing NoSuchElementException.

Add failing tests for scanning key sets where Redis returns a scan iteration pointing to the next cursor but having no actual values itself like in:

    scan 0 match key*9
      1) 1966080
      2) (empty list or set)

src/test/java/org/springframework/data/redis/connection/AbstractConnectionIntegrationTests.java

@@ -1977,6 +1977,27 @@ public abstract class AbstractConnectionIntegrationTests {
 		assertThat(i, is(itemCount));
 	}
 
+	/**
+	 * @see DATAREDIS-417
+	 */
+	@Test
+	@IfProfileValue(name = "redisVersion", value = "2.8+")
+	@WithRedisDriver({ RedisDriver.JEDIS, RedisDriver.LETTUCE })
+	public void scanShouldReadEntireValueRangeWhenIdividualScanIterationsReturnEmptyCollection() {
+
+		connection.execute("DEBUG", "POPULATE".getBytes(), "100".getBytes());
+
+		Cursor<byte[]> cursor = connection.scan(ScanOptions.scanOptions().match("key*9").count(10).build());
+
+		int i = 0;
+		while (cursor.hasNext()) {
+			assertThat(new String(cursor.next()), containsString("key:"));
+			i++;
+		}
+
+		assertThat(i, is(10));
+	}
+
 	/**
 	 * @see DATAREDIS-306
 	 */

src/test/java/org/springframework/data/redis/connection/AbstractConnectionPipelineIntegrationTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2011-2013 the original author or authors.
+ * Copyright 2011-2015 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,15 +16,14 @@
 
 package org.springframework.data.redis.connection;
 
-import org.junit.Ignore;
-import org.junit.Test;
-import org.springframework.test.annotation.IfProfileValue;
+import static org.junit.Assert.*;
 
 import java.util.ArrayList;
 import java.util.List;
 
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertTrue;
+import org.junit.Ignore;
+import org.junit.Test;
+import org.springframework.test.annotation.IfProfileValue;
 
 /**
  * Base test class for integration tests that execute each operation of a Connection while a pipeline is open, verifying
@@ -34,6 +33,7 @@ import static org.junit.Assert.assertTrue;
  * test overrides {@link AbstractConnectionIntegrationTests} when result types are different
  * 
  * @author Jennifer Hickey
+ * @author Christoph Strobl
  */
 abstract public class AbstractConnectionPipelineIntegrationTests extends AbstractConnectionIntegrationTests {
 
@@ -120,6 +120,16 @@ abstract public class AbstractConnectionPipelineIntegrationTests extends Abstrac
 		assertTrue(results.isEmpty());
 	}
 
+	/**
+	 * @see DATAREDIS-417
+	 */
+	@Test
+	@Ignore
+	@Override
+	public void scanShouldReadEntireValueRangeWhenIdividualScanIterationsReturnEmptyCollection() {
+		super.scanShouldReadEntireValueRangeWhenIdividualScanIterationsReturnEmptyCollection();
+	}
+
 	protected void initConnection() {
 		connection.openPipeline();
 	}

src/test/java/org/springframework/data/redis/connection/AbstractConnectionTransactionIntegrationTests.java

@@ -1,6 +1,22 @@
+/*
+ * Copyright 2013-2015 the original author or authors.
+ *
+ * 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
+ *
+ *      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.springframework.data.redis.connection;
 
-import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.*;
 
 import java.util.ArrayList;
 import java.util.List;
@@ -9,6 +25,11 @@ import org.junit.Ignore;
 import org.junit.Test;
 import org.springframework.test.annotation.IfProfileValue;
 
+/**
+ * @author Jennifer Hickey
+ * @author Thomas Darimont
+ * @author Christoph Strobl
+ */
 abstract public class AbstractConnectionTransactionIntegrationTests extends AbstractConnectionIntegrationTests {
 
 	@Ignore
@@ -86,6 +107,16 @@ abstract public class AbstractConnectionTransactionIntegrationTests extends Abst
 		connection.scriptKill();
 	}
 
+	/**
+	 * @see DATAREDIS-417
+	 */
+	@Test
+	@Ignore
+	@Override
+	public void scanShouldReadEntireValueRangeWhenIdividualScanIterationsReturnEmptyCollection() {
+		super.scanShouldReadEntireValueRangeWhenIdividualScanIterationsReturnEmptyCollection();
+	}
+
 	protected void initConnection() {
 		connection.multi();
 	}

src/test/java/org/springframework/data/redis/core/ScanCursorUnitTests.java

@@ -16,11 +16,15 @@
 package org.springframework.data.redis.core;
 
 import static org.hamcrest.core.Is.*;
+import static org.hamcrest.core.IsCollectionContaining.*;
 import static org.junit.Assert.*;
 
 import java.io.IOException;
+import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Collections;
 import java.util.LinkedList;
+import java.util.List;
 import java.util.NoSuchElementException;
 import java.util.Queue;
 import java.util.Stack;
@@ -163,6 +167,83 @@ public class ScanCursorUnitTests {
 		assertThat(cursor.getPosition(), is(2L));
 	}
 
+	/**
+	 * @see DATAREDIS-417
+	 */
+	@Test
+	public void hasNextShouldCallScanUntilFinishedWhenScanResultIsAnEmptyCollection() {
+
+		LinkedList<ScanIteration<String>> values = new LinkedList<ScanIteration<String>>();
+		values.add(createIteration(1, "spring"));
+		values.add(createIteration(2));
+		values.add(createIteration(3));
+		values.add(createIteration(4));
+		values.add(createIteration(5));
+		values.add(createIteration(0, "redis"));
+		Cursor<String> cursor = initCursor(values);
+
+		List<String> result = new ArrayList<String>();
+		while (cursor.hasNext()) {
+			result.add(cursor.next());
+		}
+
+		assertThat(result.size(), is(2));
+		assertThat(result, hasItems("spring", "redis"));
+	}
+
+	/**
+	 * @see DATAREDIS-417
+	 */
+	@Test
+	public void hasNextShouldStopWhenScanResultIsAnEmptyCollectionAndStateIsFinished() {
+
+		LinkedList<ScanIteration<String>> values = new LinkedList<ScanIteration<String>>();
+		values.add(createIteration(1, "spring"));
+		values.add(createIteration(2));
+		values.add(createIteration(3));
+		values.add(createIteration(4));
+		values.add(createIteration(5));
+		values.add(createIteration(6));
+		values.add(createIteration(7, "data"));
+		values.add(createIteration(0));
+		Cursor<String> cursor = initCursor(values);
+
+		List<String> result = new ArrayList<String>();
+		while (cursor.hasNext()) {
+			result.add(cursor.next());
+		}
+
+		assertThat(result.size(), is(2));
+		assertThat(result, hasItems("spring", "data"));
+	}
+
+	/**
+	 * @see DATAREDIS-417
+	 */
+	@Test
+	public void hasNextShouldStopCorrectlyWhenWholeScanIterationDoesNotReturnResultsAndStateIsFinished() {
+
+		LinkedList<ScanIteration<String>> values = new LinkedList<ScanIteration<String>>();
+		values.add(createIteration(1));
+		values.add(createIteration(2));
+		values.add(createIteration(3));
+		values.add(createIteration(4));
+		values.add(createIteration(5));
+		values.add(createIteration(0));
+		Cursor<String> cursor = initCursor(values);
+
+		assertThat(cursor.getPosition(), is(0L));
+
+		int loops = 0;
+		while (cursor.hasNext()) {
+			cursor.next();
+			loops++;
+		}
+
+		assertThat(loops, is(0));
+		assertThat(cursor.getCursorId(), is(0L));
+	}
+
 	private CapturingCursorDummy initCursor(Queue<ScanIteration<String>> values) {
 		CapturingCursorDummy cursor = new CapturingCursorDummy(values);
 		cursor.open();
@@ -170,7 +251,8 @@ public class ScanCursorUnitTests {
 	}
 
 	private ScanIteration<String> createIteration(long cursorId, String... values) {
-		return new ScanIteration<String>(cursorId, Arrays.asList(values));
+		return new ScanIteration<String>(cursorId, values.length > 0 ? Arrays.asList(values)
+				: Collections.<String> emptyList());
 	}
 
 	private class CapturingCursorDummy extends ScanCursor<String> {