fix: CSRedisCachingProvider设置CacheNulls=true导致GetAsync永远返回CacheValue.Null #223

* dataRetriever返回非空时候导致默认反序列化出现空对象异常
* dataRetriever返回非空时候不应该返回CacheValue.Null

Closes #307

Author: vla

src/EasyCaching.CSRedis/DefaultCSRedisCachingProvider.Async.cs

@@ -74,7 +74,7 @@ public override async Task<CacheValue<T>> BaseGetAsync<T>(string cacheKey, Func<
             ArgumentCheck.NotNegativeOrZero(expiration, nameof(expiration));
 
             var result = await _cache.GetAsync<byte[]>(cacheKey);
-            if (result != null || _options.CacheNulls)
+            if (result != null)
             {
                 CacheStats.OnHit();
 

test/EasyCaching.UnitTests/CachingTests/BaseCachingProviderTest.cs

@@ -521,12 +521,27 @@ public void Get_Not_Cached_Value_Should_Call_Retriever_And_Return_Null_With_Cach
 
             var res = _providerWithNullsCached.Get(cacheKey, func, _defaultTs);
 
-            Assert.Equal(default(string),res.Value);
+            Assert.Equal(default(string), res.Value);
             var cachedValue = _providerWithNullsCached.Get<string>(cacheKey);
             Assert.True(cachedValue.HasValue);
             Assert.Null(cachedValue.Value);
         }
 
+        [Fact]
+        public async Task Get_Cached_Value_Async_Should_Call_Retriever_And_Return_String_With_Caching_When_Nulls_Are_Cached()
+        {
+            var cacheKey = $"{_nameSpace}{Guid.NewGuid().ToString()}";
+            var func = Create_Fake_Retriever_Return_String_Async();
+
+            var res = await _providerWithNullsCached.GetAsync(cacheKey, func, _defaultTs);
+
+            Assert.Equal("123", res.Value);
+            var cachedValue = await _providerWithNullsCached.GetAsync<string>(cacheKey);
+            Assert.True(cachedValue.HasValue);
+            Assert.NotNull(cachedValue.Value);
+            Assert.Equal("123", cachedValue.Value);
+        }
+
         [Fact]
         public void Get_Cached_Value_Should_Not_Call_Retriever()
         {