Add a failing concurrency test

Add a test to AcceptanceTests.AppendStream that fails for postgres but passes for all other DBs. This is to reproduce a bug with concurrent appends in postgres, see: #478

Co-authored-by: Rasmus Larsson <stoft@users.noreply.github.com>

tests/SqlStreamStore.AcceptanceTests/AcceptanceTests.AppendStream.cs

@@ -6,6 +6,7 @@
     using Shouldly;
     using SqlStreamStore.Streams;
     using Xunit;
+    using System.Linq;
 
     public partial class AcceptanceTests
     {
@@ -28,7 +29,7 @@ public async Task
 
         [Fact, Trait("Category", "AppendStream")]
         public async Task
-            When_append_stream_second_time_with_no_stream_expected_and_same_messages_then_should_then_should_be_idempotent()
+            When_append_stream_second_time_with_no_stream_expected_and_same_messages_then_should_be_idempotent()
         {
             // Idempotency
             const string streamId = "stream-1";
@@ -42,7 +43,7 @@ await Store
         }
 
         [Fact, Trait("Category", "AppendStream")]
-        public async Task When_append_stream_second_time_with_no_stream_expected_and_same_messages_then_should_then_should_have_expected_result()
+        public async Task When_append_stream_second_time_with_no_stream_expected_and_same_messages_then_should_have_expected_result()
         {
             // Idempotency
             const string streamId = "stream-1";
@@ -665,7 +666,7 @@ await Store
             exception.ShouldBeOfType<WrongExpectedVersionException>(
                 ErrorMessages.AppendFailedWrongExpectedVersion(streamId, 10));
         }
-        
+
         [Theory, Trait("Category", "AppendStream")]
         [InlineData("stream/id")]
         [InlineData("stream%id")]
@@ -676,7 +677,7 @@ public async Task When_append_to_stream_with_url_encodable_characters_and_expect
             result.CurrentVersion.ShouldBe(2);
             result.CurrentPosition.ShouldBeGreaterThanOrEqualTo(Fixture.MinPosition + 2L);
         }
-        
+
         [Theory, Trait("Category", "AppendStream")]
         [InlineData("stream/id")]
         [InlineData("stream%id")]
@@ -699,7 +700,7 @@ public async Task When_append_to_stream_with_url_encodable_characters_and_expect
             result.CurrentVersion.ShouldBe(2);
             result.CurrentPosition.ShouldBeGreaterThanOrEqualTo(Fixture.MinPosition + 2L);
         }
-        
+
         [Theory, Trait("Category", "AppendStream")]
         [InlineData("stream/id")]
         [InlineData("stream%id")]
@@ -713,40 +714,56 @@ public async Task When_append_to_stream_with_url_encodable_characters_and_expect
         }
 
         [Fact, Trait("Category", "AppendStream")]
-        public async Task When_append_stream_concurrently_with_no_stream_expected_and_same_messages_then_should_then_should_have_expected_result()
+        public async Task When_append_stream_concurrently_with_no_stream_expected_and_same_messages_then_should_have_expected_result()
         {
             // Idempotency
             const string streamId = "stream-1";
-            
+
             var messages = CreateNewStreamMessages(1, 2);
             var tasks = new List<Task<AppendResult>>();
-            for(var index = 0; index < 10; index++)
+            for (var index = 0; index < 10; index++)
             {
                 tasks.Add(Store.AppendToStream(streamId, ExpectedVersion.NoStream, messages));
             }
-            
+
             var results = await Task.WhenAll(tasks);
 
             Assert.All(results, result => result.CurrentVersion.ShouldBe(1));
             Assert.All(results, result => result.CurrentPosition.ShouldBe(results[0].CurrentPosition));
         }
-        
+
         [Fact, Trait("Category", "AppendStream")]
-        public async Task When_append_to_different_streams_concurrently_with_no_stream_expected_and_same_messages_then_should_then_should_have_expected_result()
+        public async Task When_append_to_different_streams_concurrently_with_no_stream_expected_and_same_messages_then_should_have_expected_result()
         {
             // Idempotency
             const string streamPrefix = "stream-";
-            
+
             var messages = CreateNewStreamMessages(1, 2);
             var tasks = new List<Task<AppendResult>>();
-            for(var index = 0; index < 10; index++)
+            for (var index = 0; index < 10; index++)
             {
                 tasks.Add(Store.AppendToStream(streamPrefix + index, ExpectedVersion.NoStream, messages));
             }
-            
+
             var results = await Task.WhenAll(tasks);
 
             Assert.All(results, result => result.CurrentVersion.ShouldBe(1));
         }
+
+        [Fact, Trait("Category", "AppendStream")]
+        public async Task When_append_to_same_stream_concurrently_with_expected_version_any_and_different_messages_then_should_not_throw()
+        {
+            const string streamName = "stream";
+
+            var messages = CreateNewStreamMessages(1, 2, 3, 4, 5, 6, 7, 8, 9, 10);
+            var tasks = new List<Task<AppendResult>>();
+            foreach (var message in messages)
+            {
+                tasks.Add(Store.AppendToStream(streamName, ExpectedVersion.Any, new []{message}));
+            }
+
+            var results = await Task.WhenAll(tasks);
+            results.Select(r => r.CurrentVersion).Max().ShouldBe(9);
+        }
     }
 }