Simplify Position down into RedisValue (#912)

Not 100% sure this is what we figured out, but good first pass at getting there if not.

StackExchange.Redis.Tests/DatabaseWrapperTests.cs

@@ -831,8 +831,8 @@ public void StreamClaimMessagesReturningIds()
         [Fact]
         public void StreamConsumerGroupSetPosition()
         {
-            wrapper.StreamConsumerGroupSetPosition("key", "group", Position.Beginning, CommandFlags.HighPriority);
-            mock.Verify(_ => _.StreamConsumerGroupSetPosition("prefix:key", "group", Position.Beginning, CommandFlags.HighPriority));
+            wrapper.StreamConsumerGroupSetPosition("key", "group", StreamPosition.Beginning, CommandFlags.HighPriority);
+            mock.Verify(_ => _.StreamConsumerGroupSetPosition("prefix:key", "group", StreamPosition.Beginning, CommandFlags.HighPriority));
         }
 
         [Fact]
@@ -845,8 +845,8 @@ public void StreamConsumerInfoGet()
         [Fact]
         public void StreamCreateConsumerGroup()
         {
-            wrapper.StreamCreateConsumerGroup("key", "group", Position.Beginning, CommandFlags.HighPriority);
-            mock.Verify(_ => _.StreamCreateConsumerGroup("prefix:key", "group", Position.Beginning, CommandFlags.HighPriority));
+            wrapper.StreamCreateConsumerGroup("key", "group", StreamPosition.Beginning, CommandFlags.HighPriority);
+            mock.Verify(_ => _.StreamCreateConsumerGroup("prefix:key", "group", StreamPosition.Beginning, CommandFlags.HighPriority));
         }
 
         [Fact]
@@ -924,15 +924,15 @@ public void StreamRead_1()
         [Fact]
         public void StreamRead_2()
         {
-            wrapper.StreamRead("key", new Position("0-0"), null, CommandFlags.HighPriority);
-            mock.Verify(_ => _.StreamRead("prefix:key", new Position("0-0"), null, CommandFlags.HighPriority));
+            wrapper.StreamRead("key", "0-0", null, CommandFlags.HighPriority);
+            mock.Verify(_ => _.StreamRead("prefix:key", "0-0", null, CommandFlags.HighPriority));
         }
 
         [Fact]
         public void StreamStreamReadGroup_1()
         {
-            wrapper.StreamReadGroup("key", "group", "consumer", new Position("0-0"), 10, CommandFlags.HighPriority);
-            mock.Verify(_ => _.StreamReadGroup("prefix:key", "group", "consumer", new Position("0-0"), 10, CommandFlags.HighPriority));
+            wrapper.StreamReadGroup("key", "group", "consumer", "0-0", 10, CommandFlags.HighPriority);
+            mock.Verify(_ => _.StreamReadGroup("prefix:key", "group", "consumer", "0-0", 10, CommandFlags.HighPriority));
         }
 
         [Fact]

StackExchange.Redis.Tests/Streams.cs

@@ -135,15 +135,15 @@ public void StreamConsumerGroupSetId()
                 db.StreamAdd(key, "field2", "value2");
 
                 // Create a group and set the position to deliver new messages only.
-                db.StreamCreateConsumerGroup(key, groupName, Position.New);
+                db.StreamCreateConsumerGroup(key, groupName, StreamPosition.NewMessages);
 
                 // Read into the group, expect nothing
-                var firstRead = db.StreamReadGroup(key, groupName, consumer, Position.New);
+                var firstRead = db.StreamReadGroup(key, groupName, consumer, StreamPosition.NewMessages);
 
                 // Reset the ID back to read from the beginning.
-                db.StreamConsumerGroupSetPosition(key, groupName, Position.Beginning);
+                db.StreamConsumerGroupSetPosition(key, groupName, StreamPosition.Beginning);
 
-                var secondRead = db.StreamReadGroup(key, groupName, consumer, Position.New);
+                var secondRead = db.StreamReadGroup(key, groupName, consumer, StreamPosition.NewMessages);
 
                 Assert.NotNull(firstRead);
                 Assert.NotNull(secondRead);
@@ -168,7 +168,7 @@ public void StreamConsumerGroupWithNoConsumers()
                 db.StreamAdd(key, "field1", "value1");
 
                 // Create a group
-                db.StreamCreateConsumerGroup(key, groupName, new Position("0-0"));
+                db.StreamCreateConsumerGroup(key, groupName, "0-0");
 
                 // Query redis for the group consumers, expect an empty list in response.
                 var consumers = db.StreamConsumerInfo(key, groupName);
@@ -193,7 +193,7 @@ public void StreamCreateConsumerGroup()
                 db.StreamAdd(key, "field1", "value1");
 
                 // Create a group
-                var result = db.StreamCreateConsumerGroup(key, groupName, Position.Beginning);
+                var result = db.StreamCreateConsumerGroup(key, groupName, StreamPosition.Beginning);
 
                 Assert.True(result);
             }
@@ -219,7 +219,7 @@ public void StreamConsumerGroupReadOnlyNewMessagesWithEmptyResponse()
                 db.StreamCreateConsumerGroup(key, groupName);
 
                 // Read, expect no messages
-                var entries = db.StreamReadGroup(key, groupName, "test_consumer", new Position("0-0"));
+                var entries = db.StreamReadGroup(key, groupName, "test_consumer", "0-0");
 
                 Assert.True(entries.Length == 0);
             }
@@ -240,9 +240,9 @@ public void StreamConsumerGroupReadFromStreamBeginning()
                 var id1 = db.StreamAdd(key, "field1", "value1");
                 var id2 = db.StreamAdd(key, "field2", "value2");
 
-                db.StreamCreateConsumerGroup(key, groupName, Position.Beginning);
+                db.StreamCreateConsumerGroup(key, groupName, StreamPosition.Beginning);
 
-                var entries = db.StreamReadGroup(key, groupName, "test_consumer", new Position("0-0"));
+                var entries = db.StreamReadGroup(key, groupName, "test_consumer", "0-0");
 
                 Assert.True(entries.Length == 2);
                 Assert.True(id1 == entries[0].Id);
@@ -268,9 +268,9 @@ public void StreamConsumerGroupReadFromStreamBeginningWithCount()
                 var id4 = db.StreamAdd(key, "field4", "value4");
 
                 // Start reading after id1.
-                db.StreamCreateConsumerGroup(key, groupName, new Position(id1));
+                db.StreamCreateConsumerGroup(key, groupName, id1);
                 
-                var entries = db.StreamReadGroup(key, groupName, "test_consumer", Position.New, 2);
+                var entries = db.StreamReadGroup(key, groupName, "test_consumer", StreamPosition.NewMessages, 2);
 
                 // Ensure we only received the requested count and that the IDs match the expected values.
                 Assert.True(entries.Length == 2);
@@ -297,10 +297,10 @@ public void StreamConsumerGroupAcknowledgeMessage()
                 var id3 = db.StreamAdd(key, "field3", "value3");
                 var id4 = db.StreamAdd(key, "field4", "value4");
 
-                db.StreamCreateConsumerGroup(key, groupName, Position.Beginning);
+                db.StreamCreateConsumerGroup(key, groupName, StreamPosition.Beginning);
 
                 // Read all 4 messages, they will be assigned to the consumer
-                var entries = db.StreamReadGroup(key, groupName, consumer, new Position("0-0"));
+                var entries = db.StreamReadGroup(key, groupName, consumer, "0-0");
 
                 // Send XACK for 3 of the messages
 
@@ -311,7 +311,7 @@ public void StreamConsumerGroupAcknowledgeMessage()
                 var twoAck = db.StreamAcknowledge(key, groupName, new RedisValue[] { id3, id4 });
 
                 // Read the group again, it should only return the unacknowledged message.
-                var notAcknowledged = db.StreamReadGroup(key, groupName, consumer, new Position("0-0"));
+                var notAcknowledged = db.StreamReadGroup(key, groupName, consumer, "0-0");
 
                 Assert.True(entries.Length == 4);
                 Assert.Equal(1, oneAck);
@@ -340,7 +340,7 @@ public void StreamConsumerGroupClaimMessages()
                 var id3 = db.StreamAdd(key, "field3", "value3");
                 var id4 = db.StreamAdd(key, "field4", "value4");
 
-                db.StreamCreateConsumerGroup(key, groupName, new Position("0-0"));
+                db.StreamCreateConsumerGroup(key, groupName, "0-0");
 
                 // Read a single message into the first consumer.
                 db.StreamReadGroup(key, groupName, consumer1, count: 1);
@@ -391,10 +391,10 @@ public void StreamConsumerGroupClaimMessagesReturningIds()
                 var id3 = db.StreamAdd(key, "field3", "value3");
                 var id4 = db.StreamAdd(key, "field4", "value4");
 
-                db.StreamCreateConsumerGroup(key, groupName, Position.Beginning);
+                db.StreamCreateConsumerGroup(key, groupName, StreamPosition.Beginning);
 
                 // Read a single message into the first consumer.
-                var consumer1Messages = db.StreamReadGroup(key, groupName, consumer1, Position.Beginning, 1);
+                var consumer1Messages = db.StreamReadGroup(key, groupName, consumer1, StreamPosition.Beginning, 1);
 
                 // Read the remaining messages into the second consumer.
                 var consumer2Messages = db.StreamReadGroup(key, groupName, consumer2);
@@ -452,13 +452,13 @@ public void StreamConsumerGroupReadMultipleOneReadBeginningOneReadNew()
                 db.StreamCreateConsumerGroup(stream1, groupName);
 
                 // stream2 set up to read from the beginning of the stream
-                db.StreamCreateConsumerGroup(stream2, groupName, Position.Beginning);
+                db.StreamCreateConsumerGroup(stream2, groupName, StreamPosition.Beginning);
 
                 // Read for both streams from the beginning. We shouldn't get anything back for stream1.
                 var pairs = new StreamPosition[]
                 {
-                    new StreamPosition(stream1, Position.Beginning),
-                    new StreamPosition(stream2, Position.Beginning)
+                    new StreamPosition(stream1, StreamPosition.Beginning),
+                    new StreamPosition(stream2, StreamPosition.Beginning)
                 };
 
                 var streams = db.StreamReadGroup(pairs, groupName, "test_consumer");
@@ -493,8 +493,8 @@ public void StreamConsumerGroupReadMultipleOnlyNewMessagesExpectNoResult()
                 // We shouldn't get anything for either stream.
                 var pairs = new StreamPosition[]
                 {
-                    new StreamPosition(stream1, Position.Beginning),
-                    new StreamPosition(stream2, Position.Beginning)
+                    new StreamPosition(stream1, StreamPosition.Beginning),
+                    new StreamPosition(stream2, StreamPosition.Beginning)
                 };
 
                 var streams = db.StreamReadGroup(pairs, groupName, "test_consumer");
@@ -534,8 +534,8 @@ public void StreamConsumerGroupReadMultipleOnlyNewMessagesExpect1Result()
                 // Read the new messages (messages created after the group was created).
                 var pairs = new StreamPosition[]
                 {
-                    new StreamPosition(stream1, Position.New),
-                    new StreamPosition(stream2, Position.New)
+                    new StreamPosition(stream1, StreamPosition.NewMessages),
+                    new StreamPosition(stream2, StreamPosition.NewMessages)
                 };
 
                 var streams = db.StreamReadGroup(pairs, groupName, "test_consumer");
@@ -570,14 +570,14 @@ public void StreamConsumerGroupReadMultipleRestrictCount()
                 var id2_3 = db.StreamAdd(stream2, "field2-3", "value2-3");
 
                 // Allow reading from the beginning in both streams
-                db.StreamCreateConsumerGroup(stream1, groupName, Position.Beginning);
-                db.StreamCreateConsumerGroup(stream2, groupName, Position.Beginning);
+                db.StreamCreateConsumerGroup(stream1, groupName, StreamPosition.Beginning);
+                db.StreamCreateConsumerGroup(stream2, groupName, StreamPosition.Beginning);
 
                 var pairs = new StreamPosition[]
                 {
                     // Read after the first id in both streams
-                    new StreamPosition(stream1, new Position(id1_1)),
-                    new StreamPosition(stream2, new Position(id2_1))
+                    new StreamPosition(stream1, id1_1),
+                    new StreamPosition(stream2, id2_1)
                 };
 
                 // Restrict the count to 2 (expect only 1 message from first stream, 2 from the second).
@@ -605,7 +605,7 @@ public void StreamConsumerGroupViewPendingInfoNoConsumers()
 
                 var id1 = db.StreamAdd(key, "field1", "value1");
 
-                db.StreamCreateConsumerGroup(key, groupName, Position.Beginning);
+                db.StreamCreateConsumerGroup(key, groupName, StreamPosition.Beginning);
 
                 var pendingInfo = db.StreamPending(key, groupName);
 
@@ -631,7 +631,7 @@ public void StreamConsumerGroupViewPendingInfoWhenNothingPending()
 
                 var id1 = db.StreamAdd(key, "field1", "value1");
 
-                db.StreamCreateConsumerGroup(key, groupName, new Position("0-0"));
+                db.StreamCreateConsumerGroup(key, groupName, "0-0");
 
                 var pendingMessages = db.StreamPendingMessages(key,
                     groupName,
@@ -662,10 +662,10 @@ public void StreamConsumerGroupViewPendingInfoSummary()
                 var id3 = db.StreamAdd(key, "field3", "value3");
                 var id4 = db.StreamAdd(key, "field4", "value4");
 
-                db.StreamCreateConsumerGroup(key, groupName, Position.Beginning);
+                db.StreamCreateConsumerGroup(key, groupName, StreamPosition.Beginning);
 
                 // Read a single message into the first consumer.
-                var consumer1Messages = db.StreamReadGroup(key, groupName, consumer1, Position.Beginning, 1);
+                var consumer1Messages = db.StreamReadGroup(key, groupName, consumer1, StreamPosition.Beginning, 1);
 
                 // Read the remaining messages into the second consumer.
                 var consumer2Messages = db.StreamReadGroup(key, groupName, consumer2);
@@ -704,7 +704,7 @@ public async Task StreamConsumerGroupViewPendingMessageInfo()
                 var id3 = db.StreamAdd(key, "field3", "value3");
                 var id4 = db.StreamAdd(key, "field4", "value4");
 
-                db.StreamCreateConsumerGroup(key, groupName, Position.Beginning);
+                db.StreamCreateConsumerGroup(key, groupName, StreamPosition.Beginning);
 
                 // Read a single message into the first consumer.
                 var consumer1Messages = db.StreamReadGroup(key, groupName, consumer1, count: 1);
@@ -745,7 +745,7 @@ public void StreamConsumerGroupViewPendingMessageInfoForConsumer()
                 var id3 = db.StreamAdd(key, "field3", "value3");
                 var id4 = db.StreamAdd(key, "field4", "value4");
 
-                db.StreamCreateConsumerGroup(key, groupName, Position.Beginning);
+                db.StreamCreateConsumerGroup(key, groupName, StreamPosition.Beginning);
 
                 // Read a single message into the first consumer.
                 var consumer1Messages = db.StreamReadGroup(key, groupName, consumer1, count: 1);
@@ -782,8 +782,8 @@ public void StreamDeleteConsumer()
                 db.StreamAdd(key, "fiedl2", "value2");
 
                 // Create a consumer group and read the message.
-                db.StreamCreateConsumerGroup(key, groupName, Position.Beginning);
-                db.StreamReadGroup(key, groupName, consumer, Position.Beginning);
+                db.StreamCreateConsumerGroup(key, groupName, StreamPosition.Beginning);
+                db.StreamReadGroup(key, groupName, consumer, StreamPosition.Beginning);
 
                 var preDeleteConsumers = db.StreamConsumerInfo(key, groupName);
 
@@ -816,8 +816,8 @@ public void StreamDeleteConsumerGroup()
                 db.StreamAdd(key, "field1", "value1");
 
                 // Create a consumer group and read the messages.
-                db.StreamCreateConsumerGroup(key, groupName, Position.Beginning);
-                db.StreamReadGroup(key, groupName, consumer, Position.Beginning);
+                db.StreamCreateConsumerGroup(key, groupName, StreamPosition.Beginning);
+                db.StreamReadGroup(key, groupName, consumer, StreamPosition.Beginning);
 
                 var preDeleteInfo = db.StreamInfo(key);
 
@@ -900,8 +900,8 @@ public void StreamGroupInfoGet()
                 var id3 = db.StreamAdd(key, "field3", "value3");
                 var id4 = db.StreamAdd(key, "field4", "value4");
 
-                db.StreamCreateConsumerGroup(key, group1, Position.Beginning);
-                db.StreamCreateConsumerGroup(key, group2, Position.Beginning);
+                db.StreamCreateConsumerGroup(key, group1, StreamPosition.Beginning);
+                db.StreamCreateConsumerGroup(key, group2, StreamPosition.Beginning);
 
                 // Read a single message into the first consumer.
                 var consumer1Messages = db.StreamReadGroup(key, group1, consumer1, count: 1);
@@ -941,7 +941,7 @@ public void StreamGroupConsumerInfoGet()
                 var id3 = db.StreamAdd(key, "field3", "value3");
                 var id4 = db.StreamAdd(key, "field4", "value4");
 
-                db.StreamCreateConsumerGroup(key, group, Position.Beginning);
+                db.StreamCreateConsumerGroup(key, group, StreamPosition.Beginning);
                 db.StreamReadGroup(key, group, consumer1, count: 1);
                 db.StreamReadGroup(key, group, consumer2);
 
@@ -1046,7 +1046,7 @@ public void StreamPendingNoMessagesOrConsumers()
                 var id = db.StreamAdd(key, "field1", "value1");
                 db.StreamDelete(key, new RedisValue[] { id });
 
-                db.StreamCreateConsumerGroup(key, groupName, new Position("0-0"));
+                db.StreamCreateConsumerGroup(key, groupName, "0-0");
 
                 var pendingInfo = db.StreamPending(key, "test_group");
 
@@ -1061,38 +1061,38 @@ public void StreamPendingNoMessagesOrConsumers()
         [Fact]
         public void StreamPositionDefaultValueIsBeginning()
         {
-            Position position = default(Position);
+            RedisValue position = StreamPosition.Beginning;
 
-            Assert.Equal(StreamConstants.ReadMinValue, position.ResolveForCommand(RedisCommand.XREAD));
-            Assert.Equal(StreamConstants.ReadMinValue, position.ResolveForCommand(RedisCommand.XREADGROUP));
-            Assert.Equal(StreamConstants.ReadMinValue, position.ResolveForCommand(RedisCommand.XGROUP));
+            Assert.Equal(StreamConstants.ReadMinValue, StreamPosition.Resolve(position, RedisCommand.XREAD));
+            Assert.Equal(StreamConstants.ReadMinValue, StreamPosition.Resolve(position, RedisCommand.XREADGROUP));
+            Assert.Equal(StreamConstants.ReadMinValue, StreamPosition.Resolve(position, RedisCommand.XGROUP));
         }
 
         [Fact]
         public void StreamPositionValidateBeginning()
         {
-            var position = Position.Beginning;
+            var position = StreamPosition.Beginning;
 
-            Assert.Equal(StreamConstants.ReadMinValue, position.ResolveForCommand(RedisCommand.XREAD));
+            Assert.Equal(StreamConstants.ReadMinValue, StreamPosition.Resolve(position, RedisCommand.XREAD));
         }
 
         [Fact]
         public void StreamPositionValidateExplicit()
         {
             var explicitValue = "1-0";
-            var position = new Position(explicitValue);
+            var position = explicitValue;
 
-            Assert.Equal(explicitValue, position.ResolveForCommand(RedisCommand.XREAD));
+            Assert.Equal(explicitValue, StreamPosition.Resolve(position, RedisCommand.XREAD));
         }
 
         [Fact]
         public void StreamPositionValidateNew()
         {
-            var position = Position.New;
+            var position = StreamPosition.NewMessages;
 
-            Assert.Equal(StreamConstants.NewMessages, position.ResolveForCommand(RedisCommand.XGROUP));
-            Assert.Equal(StreamConstants.UndeliveredMessages, position.ResolveForCommand(RedisCommand.XREADGROUP));
-            Assert.ThrowsAny<InvalidOperationException>(() => position.ResolveForCommand(RedisCommand.XREAD));
+            Assert.Equal(StreamConstants.NewMessages, StreamPosition.Resolve(position, RedisCommand.XGROUP));
+            Assert.Equal(StreamConstants.UndeliveredMessages, StreamPosition.Resolve(position, RedisCommand.XREADGROUP));
+            Assert.ThrowsAny<InvalidOperationException>(() => StreamPosition.Resolve(position, RedisCommand.XREAD));
         }
 
         [Fact]
@@ -1111,7 +1111,7 @@ public void StreamRead()
                 var id3 = db.StreamAdd(key, "field3", "value3");
 
                 // Read the entire stream from the beginning.
-                var entries = db.StreamRead(key, new Position("0-0"));
+                var entries = db.StreamRead(key, "0-0");
 
                 Assert.True(entries.Length == 3);
                 Assert.Equal(id1, entries[0].Id);
@@ -1139,7 +1139,7 @@ public void StreamReadEmptyStream()
                 var len = db.StreamLength(key);
 
                 // Read the entire stream from the beginning.
-                var entries = db.StreamRead(key, new Position("0-0"));
+                var entries = db.StreamRead(key, "0-0");
 
                 Assert.True(entries.Length == 0);
                 Assert.Equal(0, len);
@@ -1170,8 +1170,8 @@ public void StreamReadEmptyStreams()
                 var len2 = db.StreamLength(key2);
 
                 // Read the entire stream from the beginning.
-                var entries1 = db.StreamRead(key1, new Position("0-0"));
-                var entries2 = db.StreamRead(key2, new Position("0-0"));
+                var entries1 = db.StreamRead(key1, "0-0");
+                var entries2 = db.StreamRead(key2, "0-0");
 
                 Assert.True(entries1.Length == 0);
                 Assert.True(entries2.Length == 0);
@@ -1190,8 +1190,8 @@ public void StreamReadExpectedExceptionInvalidCountMultipleStream()
 
                 var streamPositions = new StreamPosition[]
                 {
-                    new StreamPosition("key1", new Position("0-0")),
-                    new StreamPosition("key2", new Position("0-0"))
+                    new StreamPosition("key1", "0-0"),
+                    new StreamPosition("key2", "0-0")
                 };
 
 
@@ -1210,7 +1210,7 @@ public void StreamReadExpectedExceptionInvalidCountSingleStream()
                 Skip.IfMissingFeature(conn, nameof(RedisFeatures.Streams), r => r.Streams);
 
                 var db = conn.GetDatabase();
-                Assert.Throws<ArgumentOutOfRangeException>(() => db.StreamRead(key, new Position("0-0"), 0));
+                Assert.Throws<ArgumentOutOfRangeException>(() => db.StreamRead(key, "0-0", 0));
             }
         }
 
@@ -1261,8 +1261,8 @@ public void StreamReadMultipleStreams()
                 // Read from both streams at the same time.
                 var streamList = new StreamPosition[2]
                 {
-                    new StreamPosition(key1, new Position("0-0")),
-                    new StreamPosition(key2, new Position("0-0"))
+                    new StreamPosition(key1, "0-0"),
+                    new StreamPosition(key2, "0-0")
                 };
 
                 var streams = db.StreamRead(streamList);
@@ -1300,8 +1300,8 @@ public void StreamReadMultipleStreamsWithCount()
 
                 var streamList = new StreamPosition[2]
                 {
-                    new StreamPosition(key1, new Position("0-0")),
-                    new StreamPosition(key2, new Position("0-0"))
+                    new StreamPosition(key1, "0-0"),
+                    new StreamPosition(key2, "0-0")
                 };
 
                 var streams = db.StreamRead(streamList, countPerStream: 1);
@@ -1338,10 +1338,10 @@ public void StreamReadMultipleStreamsWithReadPastSecondStream()
 
                 var streamList = new StreamPosition[]
                 {
-                    new StreamPosition(key1, new Position("0-0")),
+                    new StreamPosition(key1, "0-0"),
 
                     // read past the end of stream # 2
-                    new StreamPosition(key2, new Position(id4))
+                    new StreamPosition(key2, id4)
                 };
 
                 var streams = db.StreamRead(streamList);
@@ -1374,8 +1374,8 @@ public void StreamReadMultipleStreamsWithEmptyResponse()
                 var streamList = new StreamPosition[]
                 {
                     // Read past the end of both streams.
-                    new StreamPosition(key1, new Position(id2)),
-                    new StreamPosition(key2, new Position(id4))
+                    new StreamPosition(key1, id2),
+                    new StreamPosition(key2, id4)
                 };
 
                 var streams = db.StreamRead(streamList);
@@ -1401,7 +1401,7 @@ public void StreamReadPastEndOfStream()
 
                 // Read after the final ID in the stream, we expect an empty array as a response.
 
-                var entries = db.StreamRead(key, new Position(id2));
+                var entries = db.StreamRead(key, id2);
 
                 Assert.True(entries.Length == 0);
             }
@@ -1533,7 +1533,7 @@ public void StreamReadWithAfterIdAndCount_1()
                 var id3 = db.StreamAdd(key, "field3", "value3");
 
                 // Only read a single item from the stream.
-                var entries = db.StreamRead(key, new Position(id1), 1);
+                var entries = db.StreamRead(key, id1, 1);
 
                 Assert.True(entries.Length == 1);
                 Assert.Equal(id2, entries[0].Id);
@@ -1557,7 +1557,7 @@ public void StreamReadWithAfterIdAndCount_2()
                 var id4 = db.StreamAdd(key, "field4", "value4");
 
                 // Read multiple items from the stream.
-                var entries = db.StreamRead(key, new Position(id1), 2);
+                var entries = db.StreamRead(key, id1, 2);
 
                 Assert.True(entries.Length == 2);
                 Assert.Equal(id2, entries[0].Id);

StackExchange.Redis.Tests/WrapperBaseTests.cs

@@ -796,15 +796,15 @@ public void StreamConsumerInfoGetAsync()
         [Fact]
         public void StreamConsumerGroupSetPositionAsync()
         {
-            wrapper.StreamConsumerGroupSetPositionAsync("key", "group", Position.Beginning, CommandFlags.HighPriority);
-            mock.Verify(_ => _.StreamConsumerGroupSetPositionAsync("prefix:key", "group", Position.Beginning, CommandFlags.HighPriority));
+            wrapper.StreamConsumerGroupSetPositionAsync("key", "group", StreamPosition.Beginning, CommandFlags.HighPriority);
+            mock.Verify(_ => _.StreamConsumerGroupSetPositionAsync("prefix:key", "group", StreamPosition.Beginning, CommandFlags.HighPriority));
         }
 
         [Fact]
         public void StreamCreateConsumerGroupAsync()
         {
-            wrapper.StreamCreateConsumerGroupAsync("key", "group", new Position("0-0"), CommandFlags.HighPriority);
-            mock.Verify(_ => _.StreamCreateConsumerGroupAsync("prefix:key", "group", new Position("0-0"), CommandFlags.HighPriority));
+            wrapper.StreamCreateConsumerGroupAsync("key", "group", "0-0", CommandFlags.HighPriority);
+            mock.Verify(_ => _.StreamCreateConsumerGroupAsync("prefix:key", "group", "0-0", CommandFlags.HighPriority));
         }
 
         [Fact]
@@ -882,15 +882,15 @@ public void StreamReadAsync_1()
         [Fact]
         public void StreamReadAsync_2()
         {
-            wrapper.StreamReadAsync("key", new Position("0-0"), null, CommandFlags.HighPriority);
-            mock.Verify(_ => _.StreamReadAsync("prefix:key", new Position("0-0"), null, CommandFlags.HighPriority));
+            wrapper.StreamReadAsync("key", "0-0", null, CommandFlags.HighPriority);
+            mock.Verify(_ => _.StreamReadAsync("prefix:key", "0-0", null, CommandFlags.HighPriority));
         }
 
         [Fact]
         public void StreamReadGroupAsync_1()
         {
-            wrapper.StreamReadGroupAsync("key", "group", "consumer", Position.Beginning, 10, CommandFlags.HighPriority);
-            mock.Verify(_ => _.StreamReadGroupAsync("prefix:key", "group", "consumer", Position.Beginning, 10, CommandFlags.HighPriority));
+            wrapper.StreamReadGroupAsync("key", "group", "consumer", StreamPosition.Beginning, 10, CommandFlags.HighPriority);
+            mock.Verify(_ => _.StreamReadGroupAsync("prefix:key", "group", "consumer", StreamPosition.Beginning, 10, CommandFlags.HighPriority));
         }
 
         [Fact]

StackExchange.Redis/StackExchange/Redis/Interfaces/IDatabase.cs

@@ -1472,7 +1472,7 @@ public interface IDatabase : IRedis, IDatabaseAsync
         /// <param name="position">The position from which to read for the consumer group.</param>
         /// <param name="flags">The flags to use for this operation.</param>
         /// <returns>True if successful, otherwise false.</returns>
-        bool StreamConsumerGroupSetPosition(RedisKey key, RedisValue groupName, Position position, CommandFlags flags = CommandFlags.None);
+        bool StreamConsumerGroupSetPosition(RedisKey key, RedisValue groupName, RedisValue position, CommandFlags flags = CommandFlags.None);
 
         /// <summary>
         /// Retrieve information about the consumers for the given consumer group. This is the equivalent of calling "XINFO GROUPS key group".
@@ -1489,11 +1489,11 @@ public interface IDatabase : IRedis, IDatabaseAsync
         /// </summary>
         /// <param name="key">The key of the stream.</param>
         /// <param name="groupName">The name of the group to create.</param>
-        /// <param name="position">The position to begin reading the stream. Defaults to <see cref="Position.New"/>.</param>
+        /// <param name="position">The position to begin reading the stream. Defaults to <see cref="StreamPosition.NewMessages"/>.</param>
         /// <param name="flags">The flags to use for this operation.</param>
         /// <returns>True if the group was created.</returns>
         /// <remarks>https://redis.io/topics/streams-intro</remarks>
-        bool StreamCreateConsumerGroup(RedisKey key, RedisValue groupName, Position? position = null, CommandFlags flags = CommandFlags.None);
+        bool StreamCreateConsumerGroup(RedisKey key, RedisValue groupName, RedisValue? position = null, CommandFlags flags = CommandFlags.None);
 
         /// <summary>
         /// Delete messages in the stream. This method does not delete the stream.
@@ -1600,7 +1600,7 @@ public interface IDatabase : IRedis, IDatabaseAsync
         /// <returns>Returns a value of <see cref="StreamEntry"/> for each message returned.</returns>
         /// <remarks>Equivalent of calling XREAD COUNT num STREAMS key id.</remarks>
         /// <remarks>https://redis.io/commands/xread</remarks>
-        StreamEntry[] StreamRead(RedisKey key, Position position, int? count = null, CommandFlags flags = CommandFlags.None);
+        StreamEntry[] StreamRead(RedisKey key, RedisValue position, int? count = null, CommandFlags flags = CommandFlags.None);
 
         /// <summary>
         /// Read from multiple streams.
@@ -1619,12 +1619,12 @@ public interface IDatabase : IRedis, IDatabaseAsync
         /// <param name="key">The key of the stream.</param>
         /// <param name="groupName">The name of the consumer group.</param>
         /// <param name="consumerName">The consumer name.</param>
-        /// <param name="position">The position from which to read the stream. Defaults to <see cref="Position.New"/> when null.</param>
+        /// <param name="position">The position from which to read the stream. Defaults to <see cref="StreamPosition.NewMessages"/> when null.</param>
         /// <param name="count">The maximum number of messages to return.</param>
         /// <param name="flags">The flags to use for this operation.</param>
         /// <returns>Returns a value of <see cref="StreamEntry"/> for each message returned.</returns>
         /// <remarks>https://redis.io/commands/xreadgroup</remarks>
-        StreamEntry[] StreamReadGroup(RedisKey key, RedisValue groupName, RedisValue consumerName, Position? position = null, int? count = null, CommandFlags flags = CommandFlags.None);
+        StreamEntry[] StreamReadGroup(RedisKey key, RedisValue groupName, RedisValue consumerName, RedisValue? position = null, int? count = null, CommandFlags flags = CommandFlags.None);
 
         /// <summary>
         /// Read from multiple streams into the given consumer group. The consumer group with the given <paramref name="groupName"/>

StackExchange.Redis/StackExchange/Redis/Interfaces/IDatabaseAsync.cs

@@ -1382,7 +1382,7 @@ public interface IDatabaseAsync : IRedisAsync
         /// <param name="position">The position from which to read for the consumer group.</param>
         /// <param name="flags">The flags to use for this operation.</param>
         /// <returns>True if successful, otherwise false.</returns>
-        Task<bool> StreamConsumerGroupSetPositionAsync(RedisKey key, RedisValue groupName, Position position, CommandFlags flags = CommandFlags.None);
+        Task<bool> StreamConsumerGroupSetPositionAsync(RedisKey key, RedisValue groupName, RedisValue position, CommandFlags flags = CommandFlags.None);
 
         /// <summary>
         /// Retrieve information about the consumers for the given consumer group. This is the equivalent of calling "XINFO GROUPS key group".
@@ -1399,11 +1399,11 @@ public interface IDatabaseAsync : IRedisAsync
         /// </summary>
         /// <param name="key">The key of the stream.</param>
         /// <param name="groupName">The name of the group to create.</param>
-        /// <param name="position">The position to begin reading the stream. Defaults to <see cref="Position.New"/>.</param>
+        /// <param name="position">The position to begin reading the stream. Defaults to <see cref="StreamPosition.NewMessages"/>.</param>
         /// <param name="flags">The flags to use for this operation.</param>
         /// <returns>True if the group was created.</returns>
         /// <remarks>https://redis.io/topics/streams-intro</remarks>
-        Task<bool> StreamCreateConsumerGroupAsync(RedisKey key, RedisValue groupName, Position? position = null, CommandFlags flags = CommandFlags.None);
+        Task<bool> StreamCreateConsumerGroupAsync(RedisKey key, RedisValue groupName, RedisValue? position = null, CommandFlags flags = CommandFlags.None);
 
         /// <summary>
         /// Delete messages in the stream. This method does not delete the stream.
@@ -1510,7 +1510,7 @@ public interface IDatabaseAsync : IRedisAsync
         /// <returns>Returns an instance of <see cref="StreamEntry"/> for each message returned.</returns>
         /// <remarks>Equivalent of calling XREAD COUNT num STREAMS key id.</remarks>
         /// <remarks>https://redis.io/commands/xread</remarks>
-        Task<StreamEntry[]> StreamReadAsync(RedisKey key, Position position, int? count = null, CommandFlags flags = CommandFlags.None);
+        Task<StreamEntry[]> StreamReadAsync(RedisKey key, RedisValue position, int? count = null, CommandFlags flags = CommandFlags.None);
 
         /// <summary>
         /// Read from multiple streams.
@@ -1529,12 +1529,12 @@ public interface IDatabaseAsync : IRedisAsync
         /// <param name="key">The key of the stream.</param>
         /// <param name="groupName">The name of the consumer group.</param>
         /// <param name="consumerName">The consumer name.</param>
-        /// <param name="position">The position from which to read the stream. Defaults to <see cref="Position.New"/> when null.</param>
+        /// <param name="position">The position from which to read the stream. Defaults to <see cref="StreamPosition.NewMessages"/> when null.</param>
         /// <param name="count">The maximum number of messages to return.</param>
         /// <param name="flags">The flags to use for this operation.</param>
         /// <returns>Returns a value of <see cref="StreamEntry"/> for each message returned.</returns>
         /// <remarks>https://redis.io/commands/xreadgroup</remarks>
-        Task<StreamEntry[]> StreamReadGroupAsync(RedisKey key, RedisValue groupName, RedisValue consumerName, Position? position = null, int? count = null, CommandFlags flags = CommandFlags.None);
+        Task<StreamEntry[]> StreamReadGroupAsync(RedisKey key, RedisValue groupName, RedisValue consumerName, RedisValue? position = null, int? count = null, CommandFlags flags = CommandFlags.None);
 
         /// <summary>
         /// Read from multiple streams into the given consumer group. The consumer group with the given <paramref name="groupName"/>

StackExchange.Redis/StackExchange/Redis/KeyspaceIsolation/DatabaseWrapper.cs

@@ -617,12 +617,12 @@ public RedisValue[] StreamClaimIdsOnly(RedisKey key, RedisValue consumerGroup, R
             return Inner.StreamClaimIdsOnly(ToInner(key), consumerGroup, claimingConsumer, minIdleTimeInMs, messageIds, flags);
         }
 
-        public bool StreamConsumerGroupSetPosition(RedisKey key, RedisValue groupName, Position position, CommandFlags flags = CommandFlags.None)
+        public bool StreamConsumerGroupSetPosition(RedisKey key, RedisValue groupName, RedisValue position, CommandFlags flags = CommandFlags.None)
         {
             return Inner.StreamConsumerGroupSetPosition(ToInner(key), groupName, position, flags);
         }
 
-        public bool StreamCreateConsumerGroup(RedisKey key, RedisValue groupName, Position? position = null, CommandFlags flags = CommandFlags.None)
+        public bool StreamCreateConsumerGroup(RedisKey key, RedisValue groupName, RedisValue? position = null, CommandFlags flags = CommandFlags.None)
         {
             return Inner.StreamCreateConsumerGroup(ToInner(key), groupName, position, flags);
         }
@@ -677,7 +677,7 @@ public StreamEntry[] StreamRange(RedisKey key, RedisValue? minId = null, RedisVa
             return Inner.StreamRange(ToInner(key), minId, maxId, count, messageOrder, flags);
         }
 
-        public StreamEntry[] StreamRead(RedisKey key, Position position, int? count = null, CommandFlags flags = CommandFlags.None)
+        public StreamEntry[] StreamRead(RedisKey key, RedisValue position, int? count = null, CommandFlags flags = CommandFlags.None)
         {
             return Inner.StreamRead(ToInner(key), position, count, flags);
         }
@@ -687,7 +687,7 @@ public RedisStream[] StreamRead(StreamPosition[] streamPositions, int? countPerS
             return Inner.StreamRead(streamPositions, countPerStream, flags);
         }
 
-        public StreamEntry[] StreamReadGroup(RedisKey key, RedisValue groupName, RedisValue consumerName, Position? position = null, int? count = null, CommandFlags flags = CommandFlags.None)
+        public StreamEntry[] StreamReadGroup(RedisKey key, RedisValue groupName, RedisValue consumerName, RedisValue? position = null, int? count = null, CommandFlags flags = CommandFlags.None)
         {
             return Inner.StreamReadGroup(ToInner(key), groupName, consumerName, position, count, flags);
         }

StackExchange.Redis/StackExchange/Redis/KeyspaceIsolation/WrapperBase.cs

@@ -596,12 +596,12 @@ public Task<RedisValue[]> StreamClaimIdsOnlyAsync(RedisKey key, RedisValue consu
             return Inner.StreamClaimIdsOnlyAsync(ToInner(key), consumerGroup, claimingConsumer, minIdleTimeInMs, messageIds, flags);
         }
 
-        public Task<bool> StreamConsumerGroupSetPositionAsync(RedisKey key, RedisValue groupName, Position position, CommandFlags flags = CommandFlags.None)
+        public Task<bool> StreamConsumerGroupSetPositionAsync(RedisKey key, RedisValue groupName, RedisValue position, CommandFlags flags = CommandFlags.None)
         {
             return Inner.StreamConsumerGroupSetPositionAsync(ToInner(key), groupName, position, flags);
         }
 
-        public Task<bool> StreamCreateConsumerGroupAsync(RedisKey key, RedisValue groupName, Position? position = null, CommandFlags flags = CommandFlags.None)
+        public Task<bool> StreamCreateConsumerGroupAsync(RedisKey key, RedisValue groupName, RedisValue? position = null, CommandFlags flags = CommandFlags.None)
         {
             return Inner.StreamCreateConsumerGroupAsync(ToInner(key), groupName, position, flags);
         }
@@ -656,7 +656,7 @@ public Task<StreamEntry[]> StreamRangeAsync(RedisKey key, RedisValue? minId = nu
             return Inner.StreamRangeAsync(ToInner(key), minId, maxId, count, messageOrder, flags);
         }
 
-        public Task<StreamEntry[]> StreamReadAsync(RedisKey key, Position position, int? count = null, CommandFlags flags = CommandFlags.None)
+        public Task<StreamEntry[]> StreamReadAsync(RedisKey key, RedisValue position, int? count = null, CommandFlags flags = CommandFlags.None)
         {
             return Inner.StreamReadAsync(ToInner(key), position, count, flags);
         }
@@ -666,7 +666,7 @@ public Task<RedisStream[]> StreamReadAsync(StreamPosition[] streamPositions, int
             return Inner.StreamReadAsync(streamPositions, countPerStream, flags);
         }
 
-        public Task<StreamEntry[]> StreamReadGroupAsync(RedisKey key, RedisValue groupName, RedisValue consumerName, Position? position = null, int? count = null, CommandFlags flags = CommandFlags.None)
+        public Task<StreamEntry[]> StreamReadGroupAsync(RedisKey key, RedisValue groupName, RedisValue consumerName, RedisValue? position = null, int? count = null, CommandFlags flags = CommandFlags.None)
         {
             return Inner.StreamReadGroupAsync(ToInner(key), groupName, consumerName, position, count, flags);
         }

StackExchange.Redis/StackExchange/Redis/Position.cs

-using System;
-
-namespace StackExchange.Redis
-{
-    /// <summary>
-    /// A position within a stream. Defaults to <see cref="Position.New"/>.
-    /// </summary>
-    public struct Position
-    {
-        /// <summary>
-        /// Indicate a position from which to read a stream.
-        /// </summary>
-        /// <param name="readAfter">The position from which to read a stream.</param>
-        public Position(RedisValue readAfter)
-        {
-            if (readAfter == RedisValue.Null) throw new ArgumentNullException(nameof(readAfter), "readAfter cannot be RedisValue.Null.");
-
-            Kind = PositionKind.Explicit;
-            ExplicitValue = readAfter;
-        }
-
-        private Position(PositionKind kind)
-        {
-            Kind = kind;
-            ExplicitValue = RedisValue.Null;
-        }
-
-        private PositionKind Kind { get; }
-
-        private RedisValue ExplicitValue { get; }
-
-        /// <summary>
-        /// Read new messages.
-        /// </summary>
-        public static Position New = new Position(PositionKind.New);
-
-        /// <summary>
-        /// Read from the beginning of a stream.
-        /// </summary>
-        public static Position Beginning = new Position(PositionKind.Beginning);
-
-        internal RedisValue ResolveForCommand(RedisCommand command)
-        {
-            if (Kind == PositionKind.Explicit) return ExplicitValue;
-            if (Kind == PositionKind.Beginning) return StreamConstants.ReadMinValue;
-
-            // PositionKind.New
-            if (command == RedisCommand.XREAD) throw new InvalidOperationException("Position.New cannot be used with StreamRead.");
-            if (command == RedisCommand.XREADGROUP) return StreamConstants.UndeliveredMessages;
-            if (command == RedisCommand.XGROUP) return StreamConstants.NewMessages;
-            
-            throw new ArgumentException($"Unsupported command in ResolveForCommand: {command}.", nameof(command));
-        }
-    }
-}
-
-

StackExchange.Redis/StackExchange/Redis/RedisDatabase.cs

@@ -1703,7 +1703,7 @@ public Task<RedisValue[]> StreamClaimIdsOnlyAsync(RedisKey key, RedisValue consu
             return ExecuteAsync(msg, ResultProcessor.RedisValueArray);
         }
 
-        public bool StreamConsumerGroupSetPosition(RedisKey key, RedisValue groupName, Position position, CommandFlags flags = CommandFlags.None)
+        public bool StreamConsumerGroupSetPosition(RedisKey key, RedisValue groupName, RedisValue position, CommandFlags flags = CommandFlags.None)
         {
             var msg = Message.Create(Database,
                 flags,
@@ -1713,13 +1713,13 @@ public bool StreamConsumerGroupSetPosition(RedisKey key, RedisValue groupName, P
                     StreamConstants.SetId,
                     key.AsRedisValue(),
                     groupName,
-                    position.ResolveForCommand(RedisCommand.XGROUP)
+                    StreamPosition.Resolve(position, RedisCommand.XGROUP)
                 });
 
             return ExecuteSync(msg, ResultProcessor.Boolean);
         }
 
-        public Task<bool> StreamConsumerGroupSetPositionAsync(RedisKey key, RedisValue groupName, Position position, CommandFlags flags = CommandFlags.None)
+        public Task<bool> StreamConsumerGroupSetPositionAsync(RedisKey key, RedisValue groupName, RedisValue position, CommandFlags flags = CommandFlags.None)
         {
             var msg = Message.Create(Database,
                 flags,
@@ -1729,15 +1729,15 @@ public Task<bool> StreamConsumerGroupSetPositionAsync(RedisKey key, RedisValue g
                     StreamConstants.SetId,
                     key.AsRedisValue(),
                     groupName,
-                    position.ResolveForCommand(RedisCommand.XGROUP)
+                    StreamPosition.Resolve(position, RedisCommand.XGROUP)
                 });
 
             return ExecuteAsync(msg, ResultProcessor.Boolean);
         }
 
-        public bool StreamCreateConsumerGroup(RedisKey key, RedisValue groupName, Position? position = null, CommandFlags flags = CommandFlags.None)
+        public bool StreamCreateConsumerGroup(RedisKey key, RedisValue groupName, RedisValue? position = null, CommandFlags flags = CommandFlags.None)
         {
-            var actualPosition = position ?? Position.New;
+            var actualPosition = position ?? StreamConstants.NewMessages;
 
             var msg = Message.Create(Database,
                 flags,
@@ -1747,15 +1747,15 @@ public bool StreamCreateConsumerGroup(RedisKey key, RedisValue groupName, Positi
                     StreamConstants.Create,
                     key.AsRedisValue(),
                     groupName,
-                    actualPosition.ResolveForCommand(RedisCommand.XGROUP)
+                    StreamPosition.Resolve(actualPosition, RedisCommand.XGROUP)
                 });
 
             return ExecuteSync(msg, ResultProcessor.Boolean);
         }
 
-        public Task<bool> StreamCreateConsumerGroupAsync(RedisKey key, RedisValue groupName, Position? position = null, CommandFlags flags = CommandFlags.None)
+        public Task<bool> StreamCreateConsumerGroupAsync(RedisKey key, RedisValue groupName, RedisValue? position = null, CommandFlags flags = CommandFlags.None)
         {
-            var actualPosition = position ?? Position.New;
+            var actualPosition = position ?? StreamPosition.NewMessages;
 
             var msg = Message.Create(Database,
                 flags,
@@ -1765,7 +1765,7 @@ public Task<bool> StreamCreateConsumerGroupAsync(RedisKey key, RedisValue groupN
                     StreamConstants.Create,
                     key.AsRedisValue(),
                     groupName,
-                    actualPosition.ResolveForCommand(RedisCommand.XGROUP)
+                    StreamPosition.Resolve(actualPosition, RedisCommand.XGROUP)
                 });
 
             return ExecuteAsync(msg, ResultProcessor.Boolean);
@@ -1983,20 +1983,20 @@ public Task<StreamEntry[]> StreamRangeAsync(RedisKey key, RedisValue? minId = nu
             return ExecuteAsync(msg, ResultProcessor.SingleStream);
         }
 
-        public StreamEntry[] StreamRead(RedisKey key, Position position, int? count = null, CommandFlags flags = CommandFlags.None)
+        public StreamEntry[] StreamRead(RedisKey key, RedisValue position, int? count = null, CommandFlags flags = CommandFlags.None)
         {
             var msg = GetSingleStreamReadMessage(key,
-                position.ResolveForCommand(RedisCommand.XREAD),
+                StreamPosition.Resolve(position, RedisCommand.XREAD),
                 count,
                 flags);
 
             return ExecuteSync(msg, ResultProcessor.SingleStreamWithNameSkip);
         }
 
-        public Task<StreamEntry[]> StreamReadAsync(RedisKey key, Position position, int? count = null, CommandFlags flags = CommandFlags.None)
+        public Task<StreamEntry[]> StreamReadAsync(RedisKey key, RedisValue position, int? count = null, CommandFlags flags = CommandFlags.None)
         {
             var msg = GetSingleStreamReadMessage(key,
-                position.ResolveForCommand(RedisCommand.XREAD),
+                StreamPosition.Resolve(position, RedisCommand.XREAD),
                 count,
                 flags);
 
@@ -2015,28 +2015,28 @@ public Task<RedisStream[]> StreamReadAsync(StreamPosition[] streamPositions, int
             return ExecuteAsync(msg, ResultProcessor.MultiStream);
         }
 
-        public StreamEntry[] StreamReadGroup(RedisKey key, RedisValue groupName, RedisValue consumerName, Position? position = null, int? count = null, CommandFlags flags = CommandFlags.None)
+        public StreamEntry[] StreamReadGroup(RedisKey key, RedisValue groupName, RedisValue consumerName, RedisValue? position = null, int? count = null, CommandFlags flags = CommandFlags.None)
         {
-            var actualPosition = position ?? Position.New;
+            var actualPosition = position ?? StreamPosition.NewMessages;
 
             var msg = GetStreamReadGroupMessage(key,
                 groupName,
                 consumerName,
-                actualPosition.ResolveForCommand(RedisCommand.XREADGROUP),
+                StreamPosition.Resolve(actualPosition, RedisCommand.XREADGROUP),
                 count,
                 flags);
 
             return ExecuteSync(msg, ResultProcessor.SingleStreamWithNameSkip);
         }
 
-        public Task<StreamEntry[]> StreamReadGroupAsync(RedisKey key, RedisValue groupName, RedisValue consumerName, Position? position = null, int? count = null, CommandFlags flags = CommandFlags.None)
+        public Task<StreamEntry[]> StreamReadGroupAsync(RedisKey key, RedisValue groupName, RedisValue consumerName, RedisValue? position = null, int? count = null, CommandFlags flags = CommandFlags.None)
         {
-            var actualPosition = position ?? Position.New;
+            var actualPosition = position ?? StreamPosition.NewMessages;
 
             var msg = GetStreamReadGroupMessage(key,
                 groupName,
                 consumerName,
-                actualPosition.ResolveForCommand(RedisCommand.XREADGROUP),
+                StreamPosition.Resolve(actualPosition, RedisCommand.XREADGROUP),
                 count,
                 flags);
 
@@ -2459,7 +2459,7 @@ private Message GetMultiStreamReadGroupMessage(StreamPosition[] streamPositions,
             for (var i = 0; i < pairCount; i++)
             {
                 values[offset] = streamPositions[i].Key.AsRedisValue();
-                values[offset + pairCount] = streamPositions[i].Position.ResolveForCommand(RedisCommand.XREADGROUP);
+                values[offset + pairCount] = StreamPosition.Resolve(streamPositions[i].Position, RedisCommand.XREADGROUP);
 
                 offset++;
             }
@@ -2515,7 +2515,7 @@ private Message GetMultiStreamReadMessage(StreamPosition[] streamPositions, int?
             for (var i = 0; i < pairCount; i++)
             {
                 values[offset] = streamPositions[i].Key.AsRedisValue();
-                values[offset + pairCount] = streamPositions[i].Position.ResolveForCommand(RedisCommand.XREAD);
+                values[offset + pairCount] = StreamPosition.Resolve(streamPositions[i].Position, RedisCommand.XREAD);
 
                 offset++;
             }

StackExchange.Redis/StackExchange/Redis/StreamPosition.cs

-namespace StackExchange.Redis
+using System;
+
+namespace StackExchange.Redis
 {
     /// <summary>
     /// Describes a pair consisting of the Stream Key and the <see cref="Position"/> from which to begin reading a stream.
     /// </summary>
     public struct StreamPosition
     {
+        /// <summary>
+        /// Read from the beginning of a stream.
+        /// </summary>
+        public static RedisValue Beginning => StreamConstants.ReadMinValue;
+
+        /// <summary>
+        /// Read new messages.
+        /// </summary>
+        public static RedisValue NewMessages => StreamConstants.NewMessages;
+
         /// <summary>
         /// Initializes a <see cref="StreamPosition"/> value.
         /// </summary>
         /// <param name="key">The key for the stream.</param>
         /// <param name="position">The position from which to begin reading the stream.</param>
-        public StreamPosition(RedisKey key, Position position)
+        public StreamPosition(RedisKey key, RedisValue position)
         {
             Key = key;
             Position = position;
@@ -24,6 +36,22 @@ public StreamPosition(RedisKey key, Position position)
         /// <summary>
         /// The offset at which to begin reading the stream.
         /// </summary>
-        public Position Position { get; }
+        public RedisValue Position { get; }
+
+        internal static RedisValue Resolve(RedisValue value, RedisCommand command)
+        {
+            if (value == NewMessages)
+            {
+                switch (command)
+                {
+                    case RedisCommand.XREAD: throw new InvalidOperationException("StreamPosition.NewMessages cannot be used with StreamRead.");
+                    case RedisCommand.XREADGROUP: return StreamConstants.UndeliveredMessages;
+                    case RedisCommand.XGROUP: return StreamConstants.NewMessages;
+                    default: // new is only valid for the above
+                        throw new ArgumentException($"Unsupported command in StreamPosition.Resolve: {command}.", nameof(command));
+                }
+            }
+            return value;
+        }
     }
 }