Add a default sliding expiration of 30 seconds on Memory and Distributed Cache Tag Helpers.

src/Microsoft.AspNetCore.Mvc.TagHelpers/CacheTagHelper.cs

@@ -153,19 +153,23 @@ namespace Microsoft.AspNetCore.Mvc.TagHelpers
         // Internal for unit testing
         internal MemoryCacheEntryOptions GetMemoryCacheEntryOptions()
         {
+            var hasEvictionCriteria = false;
             var options = new MemoryCacheEntryOptions();
             if (ExpiresOn != null)
             {
+                hasEvictionCriteria = true;
                 options.SetAbsoluteExpiration(ExpiresOn.Value);
             }
 
             if (ExpiresAfter != null)
             {
+                hasEvictionCriteria = true;
                 options.SetAbsoluteExpiration(ExpiresAfter.Value);
             }
 
             if (ExpiresSliding != null)
             {
+                hasEvictionCriteria = true;
                 options.SetSlidingExpiration(ExpiresSliding.Value);
             }
 
@@ -174,6 +178,11 @@ namespace Microsoft.AspNetCore.Mvc.TagHelpers
                 options.SetPriority(Priority.Value);
             }
 
+            if (!hasEvictionCriteria)
+            {
+                options.SetSlidingExpiration(DefaultExpiration);
+            }
+
             return options;
         }
 

src/Microsoft.AspNetCore.Mvc.TagHelpers/CacheTagHelperBase.cs

@@ -25,6 +25,13 @@ namespace Microsoft.AspNetCore.Mvc.TagHelpers
         private const string ExpiresSlidingAttributeName = "expires-sliding";
         private const string EnabledAttributeName = "enabled";
 
+        /// <summary>
+        /// The default duration, from the time the cache entry was added, when it should be evicted.
+        /// This default duration will only be used if no other expiration criteria is specified.
+        /// The default expiration time is a sliding expiration of 30 seconds.
+        /// </summary>
+        public static readonly TimeSpan DefaultExpiration = TimeSpan.FromSeconds(30);
+
         /// <summary>
         /// Creates a new <see cref="CacheTagHelperBase"/>.
         /// </summary>
@@ -109,6 +116,5 @@ namespace Microsoft.AspNetCore.Mvc.TagHelpers
         /// </summary>
         [HtmlAttributeName(EnabledAttributeName)]
         public bool Enabled { get; set; } = true;
-
     }
 }

src/Microsoft.AspNetCore.Mvc.TagHelpers/DistributedCacheTagHelper.cs

@@ -85,24 +85,32 @@ namespace Microsoft.AspNetCore.Mvc.TagHelpers
         // Internal for unit testing
         internal DistributedCacheEntryOptions GetDistributedCacheEntryOptions()
         {
+            var hasEvictionCriteria = false;
             var options = new DistributedCacheEntryOptions();
             if (ExpiresOn != null)
             {
+                hasEvictionCriteria = true;
                 options.SetAbsoluteExpiration(ExpiresOn.Value);
             }
 
             if (ExpiresAfter != null)
             {
+                hasEvictionCriteria = true;
                 options.SetAbsoluteExpiration(ExpiresAfter.Value);
             }
 
             if (ExpiresSliding != null)
             {
+                hasEvictionCriteria = true;
                 options.SetSlidingExpiration(ExpiresSliding.Value);
             }
 
+            if (!hasEvictionCriteria)
+            {
+                options.SetSlidingExpiration(DefaultExpiration);
+            }
+
             return options;
         }
-
     }
-}
+}

test/Microsoft.AspNetCore.Mvc.TagHelpers.Test/CacheTagHelperTest.cs

@@ -210,6 +210,21 @@ namespace Microsoft.AspNetCore.Mvc.TagHelpers
             Assert.Equal(expiresOn, cacheEntryOptions.AbsoluteExpiration);
         }
 
+        [Fact]
+        public void UpdateCacheEntryOptions_DefaultsTo30SecondsSliding_IfNoEvictionCriteriaIsProvided()
+        {
+            // Arrange
+            var slidingExpiresIn = TimeSpan.FromSeconds(30);
+            var cache = new MemoryCache(new MemoryCacheOptions());
+            var cacheTagHelper = new CacheTagHelper(cache, new HtmlTestEncoder());
+
+            // Act
+            var cacheEntryOptions = cacheTagHelper.GetMemoryCacheEntryOptions();
+
+            // Assert
+            Assert.Equal(slidingExpiresIn, cacheEntryOptions.SlidingExpiration);
+        }
+
         [Fact]
         public void UpdateCacheEntryOptions_SetsAbsoluteExpiration_IfExpiresAfterIsSet()
         {

test/Microsoft.AspNetCore.Mvc.TagHelpers.Test/DistributedCacheTagHelperTest.cs

@@ -271,6 +271,29 @@ namespace Microsoft.AspNetCore.Mvc.TagHelpers
             Assert.Equal(expiresOn, cacheEntryOptions.AbsoluteExpiration);
         }
 
+        [Fact]
+        public void UpdateCacheEntryOptions_DefaultsTo30SecondsSliding_IfNoEvictionCriteriaIsProvided()
+        {
+            // Arrange
+            var slidingExpiresIn = TimeSpan.FromSeconds(30);
+            var storage = GetStorage();
+            var service = new DistributedCacheTagHelperService(
+                storage,
+                Mock.Of<IDistributedCacheTagHelperFormatter>(),
+                new HtmlTestEncoder(),
+                NullLoggerFactory.Instance
+                );
+            var cacheTagHelper = new DistributedCacheTagHelper(
+                service,
+                new HtmlTestEncoder());
+
+            // Act
+            var cacheEntryOptions = cacheTagHelper.GetDistributedCacheEntryOptions();
+
+            // Assert
+            Assert.Equal(slidingExpiresIn, cacheEntryOptions.SlidingExpiration);
+        }
+
         [Fact]
         public void UpdateCacheEntryOptions_SetsAbsoluteExpiration_IfExpiresAfterIsSet()
         {