Move deprecated tests to one place, add WriteBuffer tests

Also removes the 4096 value and set it to always-zero, since that's the effective behavior until removal.

StackExchange.Redis.Tests/Deprecated.cs

+using System;
+using Xunit;
+using Xunit.Abstractions;
+
+namespace StackExchange.Redis.Tests
+{
+    /// <summary>
+    /// Testing that things we depcreate still parse, but are otherwise defaults.
+    /// </summary>
+    public class Deprecated : TestBase
+    {
+        public Deprecated(ITestOutputHelper output) : base(output) { }
+
+#pragma warning disable CS0618 // Type or member is obsolete
+        [Fact]
+        public void PreserveAsyncOrder()
+        {
+            Assert.True(Attribute.IsDefined(typeof(ConfigurationOptions).GetProperty(nameof(ConfigurationOptions.PreserveAsyncOrder)), typeof(ObsoleteAttribute)));
+
+            var options = ConfigurationOptions.Parse("name=Hello");
+            Assert.False(options.PreserveAsyncOrder);
+
+            options = ConfigurationOptions.Parse("preserveAsyncOrder=true");
+            Assert.Equal("", options.ToString());
+            Assert.False(options.PreserveAsyncOrder);
+
+            options = ConfigurationOptions.Parse("preserveAsyncOrder=false");
+            Assert.Equal("", options.ToString());
+            Assert.False(options.PreserveAsyncOrder);
+        }
+
+        [Fact]
+        public void WriteBufferParse()
+        {
+            Assert.True(Attribute.IsDefined(typeof(ConfigurationOptions).GetProperty(nameof(ConfigurationOptions.WriteBuffer)), typeof(ObsoleteAttribute)));
+
+            var options = ConfigurationOptions.Parse("name=Hello");
+            Assert.Equal(0, options.WriteBuffer);
+
+            options = ConfigurationOptions.Parse("writeBuffer=8092");
+            Assert.Equal(0, options.WriteBuffer);
+        }
+#pragma warning restore CS0618 // Type or member is obsolete
+    }
+}

StackExchange.Redis.Tests/Issues/Issue791.cs

-using Xunit;
-using Xunit.Abstractions;
-
-namespace StackExchange.Redis.Tests.Issues
-{
-    public class Issue791 : TestBase
-    {
-        public Issue791(ITestOutputHelper output) : base(output) { }
-
-        [Fact]
-        public void PreserveAsyncOrderImplicitValue_ParsedFromConnectionString()
-        {
-            // We only care that it parses successfully while deprecated
-            var options = ConfigurationOptions.Parse("preserveAsyncOrder=true");
-            Assert.Equal("", options.ToString());
-
-            // We only care that it parses successfully while deprecated
-            options = ConfigurationOptions.Parse("preserveAsyncOrder=false");
-            Assert.Equal("", options.ToString());
-        }
-
-        [Fact]
-        public void DefaultValue_IsTrue()
-        {
-            var options = ConfigurationOptions.Parse("ssl=true");
-        }
-
-        [Fact]
-        public void PreserveAsyncOrder_SetConnectionMultiplexerProperty()
-        {
-            using (var multiplexer = ConnectionMultiplexer.Connect(TestConfig.Current.MasterServerAndPort + ",preserveAsyncOrder=false"))
-            {
-                // We only care that it parses successfully while deprecated
-            }
-        }
-    }
-}

StackExchange.Redis/StackExchange/Redis/ConfigurationOptions.cs

@@ -362,7 +362,7 @@ public bool PreserveAsyncOrder
         /// The size of the output buffer to use
         /// </summary>
         [Obsolete("This setting no longer has any effect, and should not be used")]
-        public int WriteBuffer { get { return writeBuffer.GetValueOrDefault(4096); } set { writeBuffer = value; } }
+        public int WriteBuffer { get { return 0; } set { } }
 
         internal LocalCertificateSelectionCallback CertificateSelectionCallback { get { return CertificateSelection; } private set { CertificateSelection = value; } }