chore: add eventual consistency test (#594)

tests/Integration/Momento.Sdk.Tests/Cache/ReplicaReadTest.cs

@@ -0,0 +1,45 @@
+using System.Linq;
+using System.Threading.Tasks;
+
+namespace Momento.Sdk.Tests.Integration.Cache;
+
+[Collection("CacheClient")]
+public class ReplicaReadTest : TestBase
+{
+    private new readonly ICacheClient client;
+    public ReplicaReadTest(CacheClientFixture fixture) : base(fixture)
+    {
+        client = fixture.ClientWithBalancedReads;
+    }
+
+    [Fact]
+    public async Task LatestValueAfterReplicationDelay()
+    {
+        const int numTrials = 10;
+        const int delayBetweenTrials = 100;
+        const int replicationDelayMs = 1000;
+        var random = new Random();
+
+        var trials = Enumerable.Range(0, numTrials).Select(async trialNumber =>
+        {
+            var startDelay = (trialNumber + 1) * delayBetweenTrials + (random.NextDouble() - 0.5) * 10;
+            await Task.Delay((int)startDelay);
+
+            var key = Utils.NewGuidString();
+            var value = Utils.NewGuidString();
+
+            var setResponse = await client.SetAsync(cacheName, key, value);
+            Assert.True(setResponse is CacheSetResponse.Success, $"Unexpected response: {setResponse}");
+
+            await Task.Delay(replicationDelayMs);
+
+            var getResponse = await client.GetAsync(cacheName, key);
+            Assert.True(getResponse is CacheGetResponse.Hit, $"Unexpected response: {getResponse}");
+            var hitResponse = (CacheGetResponse.Hit)getResponse;
+            string setValue = hitResponse.ValueString;
+            Assert.Equal(value, setValue);
+        });
+
+        await Task.WhenAll(trials);
+    }
+}

tests/Integration/Momento.Sdk.Tests/Fixtures.cs

@@ -11,11 +11,13 @@ namespace Momento.Sdk.Tests.Integration;
 /// </summary>
 public class CacheClientFixture : IDisposable
 {
-    public ICacheClient Client { get; private set; }
-    public ICredentialProvider AuthProvider { get; private set; }
-    public string CacheName { get; private set; }
+    public ICacheClient Client { get; }
+    public ICacheClient ClientWithConsistentReads { get; }
+    public ICacheClient ClientWithBalancedReads { get; }
+    public ICredentialProvider AuthProvider { get; }
+    public string CacheName { get; }
 
-    public TimeSpan DefaultTtl { get; private set; } = TimeSpan.FromSeconds(10);
+    public TimeSpan DefaultTtl { get; } = TimeSpan.FromSeconds(10);
 
     public CacheClientFixture()
     {
@@ -35,14 +37,14 @@ public CacheClientFixture()
             builder.AddFilter("Grpc.Net.Client", LogLevel.Error);
             builder.SetMinimumLevel(LogLevel.Information);
         }));
-
-        if (consistentReads)
-        {
-            config = config.WithReadConcern(ReadConcern.Consistent);
-        }
+        var configWithConsistentReads = config.WithReadConcern(ReadConcern.Consistent);
+
+        ClientWithBalancedReads = new CacheClient(config, AuthProvider, defaultTtl: DefaultTtl);
+        ClientWithConsistentReads = new CacheClient(configWithConsistentReads, AuthProvider, defaultTtl: DefaultTtl);
+        Client = consistentReads ? ClientWithConsistentReads : ClientWithBalancedReads;
 
         CacheName = $"dotnet-integration-{Utils.NewGuidString()}";
-        Client = new CacheClient(config, AuthProvider, defaultTtl: DefaultTtl);
+
         Utils.CreateCacheForTest(Client, CacheName);
     }