Cache should use weak comparison for ETags

Author: JunTaoLuo

src/Microsoft.AspNetCore.ResponseCaching/ResponseCacheMiddleware.cs

@@ -336,7 +336,7 @@ internal static bool ConditionalRequestSatisfied(ResponseCacheContext context)
                 {
                     foreach (var tag in ifNoneMatchHeader)
                     {
-                        if (cachedResponseHeaders.ETag.Compare(tag, useStrongComparison: true))
+                        if (cachedResponseHeaders.ETag.Compare(tag, useStrongComparison: false))
                         {
                             return true;
                         }

test/Microsoft.AspNetCore.ResponseCaching.Tests/ResponseCacheMiddlewareTests.cs

@@ -196,16 +196,31 @@ public void ConditionalRequestSatisfied_IfNoneMatch_AnyWithoutETagInResponse_Pas
             Assert.False(ResponseCacheMiddleware.ConditionalRequestSatisfied(context));
         }
 
-        [Fact]
-        public void ConditionalRequestSatisfied_IfNoneMatch_ExplicitWithMatch_Passes()
+        public static TheoryData<EntityTagHeaderValue, EntityTagHeaderValue> EquivalentWeakETags
+        {
+            get
+            {
+                return new TheoryData<EntityTagHeaderValue, EntityTagHeaderValue>
+                {
+                    { new EntityTagHeaderValue("\"tag\""), new EntityTagHeaderValue("\"tag\"") },
+                    { new EntityTagHeaderValue("\"tag\"", true), new EntityTagHeaderValue("\"tag\"") },
+                    { new EntityTagHeaderValue("\"tag\""), new EntityTagHeaderValue("\"tag\"", true) },
+                    { new EntityTagHeaderValue("\"tag\"", true), new EntityTagHeaderValue("\"tag\"", true) }
+                };
+            }
+        }
+
+        [Theory]
+        [MemberData(nameof(EquivalentWeakETags))]
+        public void ConditionalRequestSatisfied_IfNoneMatch_ExplicitWithMatch_Passes(EntityTagHeaderValue responseETag, EntityTagHeaderValue requestETag)
         {
             var context = TestUtils.CreateTestContext();
             context.CachedResponseHeaders = new ResponseHeaders(new HeaderDictionary())
             {
-                ETag = new EntityTagHeaderValue("\"E1\"")
+                ETag = responseETag
             };
 
-            context.TypedRequestHeaders.IfNoneMatch = new List<EntityTagHeaderValue>(new[] { new EntityTagHeaderValue("\"E1\"") });
+            context.TypedRequestHeaders.IfNoneMatch = new List<EntityTagHeaderValue>(new[] { requestETag });
 
             Assert.True(ResponseCacheMiddleware.ConditionalRequestSatisfied(context));
         }