Implement deferred WaitQueue, DiskAvailability, and NoOpCache behavior with tests

dotnet/src/ZB.MOM.NatsNet.Server/Auth/Ocsp/OcspTypes.cs

@@ -153,15 +153,105 @@ public interface IOcspResponseCache
     void    Remove(string key);
 }
 
+/// <summary>
+/// Runtime counters for OCSP response cache behavior.
+/// Mirrors Go <c>OCSPResponseCacheStats</c> shape.
+/// </summary>
+public sealed class OcspResponseCacheStats
+{
+    public long Responses { get; set; }
+    public long Hits { get; set; }
+    public long Misses { get; set; }
+    public long Revokes { get; set; }
+    public long Goods { get; set; }
+    public long Unknowns { get; set; }
+}
+
 /// <summary>
 /// A no-op OCSP cache that never stores anything.
 /// Mirrors Go <c>NoOpCache</c> in server/ocsp_responsecache.go.
 /// </summary>
 internal sealed class NoOpCache : IOcspResponseCache
 {
-    public byte[]? Get(string key)             => null;
-    public void    Put(string key, byte[] response) { }
-    public void    Remove(string key)          { }
+    private readonly Lock _mu = new();
+    private readonly OcspResponseCacheConfig _config;
+    private OcspResponseCacheStats? _stats;
+    private bool _online;
+
+    public NoOpCache()
+        : this(new OcspResponseCacheConfig { Type = "none" })
+    {
+    }
+
+    public NoOpCache(OcspResponseCacheConfig config)
+    {
+        _config = config;
+    }
+
+    public byte[]? Get(string key) => null;
+
+    public void Put(string key, byte[] response) { }
+
+    public void Remove(string key) => Delete(key);
+
+    public void Delete(string key)
+    {
+        _ = key;
+    }
+
+    public void Start(NatsServer? server = null)
+    {
+        lock (_mu)
+        {
+            _stats = new OcspResponseCacheStats();
+            _online = true;
+        }
+    }
+
+    public void Stop(NatsServer? server = null)
+    {
+        lock (_mu)
+        {
+            _online = false;
+        }
+    }
+
+    public bool Online()
+    {
+        lock (_mu)
+        {
+            return _online;
+        }
+    }
+
+    public string Type() => "none";
+
+    public OcspResponseCacheConfig Config()
+    {
+        lock (_mu)
+        {
+            return _config;
+        }
+    }
+
+    public OcspResponseCacheStats? Stats()
+    {
+        lock (_mu)
+        {
+            if (_stats is null)
+                return null;
+
+            return new OcspResponseCacheStats
+            {
+                Responses = _stats.Responses,
+                Hits = _stats.Hits,
+                Misses = _stats.Misses,
+                Revokes = _stats.Revokes,
+                Goods = _stats.Goods,
+                Unknowns = _stats.Unknowns,
+            };
+        }
+    }
 }
 
 /// <summary>