fixed disk provider tryset after expired (#280)

src/EasyCaching.Disk/DefaultDiskCachingProvider.Async.cs

@@ -428,7 +428,7 @@ public override async Task<bool> BaseTrySetAsync<T>(string cacheKey, T cacheValu
 
             var bytes = BuildDiskCacheValue(cacheValue, expiration);
 
-            using (FileStream stream = new FileStream(path, FileMode.CreateNew, FileAccess.Write, FileShare.None))
+            using (FileStream stream = new FileStream(path, FileMode.OpenOrCreate, FileAccess.Write, FileShare.None))
             {
                 await stream.WriteAsync(bytes, 0, bytes.Length);
                 AppendKey(cacheKey, fileName);

src/EasyCaching.Disk/DefaultDiskCachingProvider.cs

@@ -525,7 +525,7 @@ public override bool BaseTrySet<T>(string cacheKey, T cacheValue, TimeSpan expir
 
             var bytes = BuildDiskCacheValue(cacheValue, expiration);
 
-            using (FileStream stream = new FileStream(path, FileMode.CreateNew, FileAccess.Write, FileShare.None))
+            using (FileStream stream = new FileStream(path, FileMode.OpenOrCreate, FileAccess.Write, FileShare.None))
             {
                 stream.Write(bytes, 0, bytes.Length);
                 AppendKey(cacheKey, fileName);

test/EasyCaching.UnitTests/CachingTests/DiskCachingProviderTest.cs

@@ -40,5 +40,47 @@ protected override Task GetAsync_Parallel_Should_Succeed()
         {
             return Task.CompletedTask;
         }
+
+        [Fact]
+        public async Task TrySetAgainAsync_After_Expired_Should_Succed()
+        {
+            var key = Guid.NewGuid().ToString();
+            var v1 = "123456";
+            var res1 = await _provider.TrySetAsync<string>(key, v1, TimeSpan.FromSeconds(1));
+            Assert.True(res1);
+
+            await Task.Delay(TimeSpan.FromSeconds(2));
+            var res2 = await _provider.TrySetAsync<string>(key, v1, TimeSpan.FromSeconds(5));
+            Assert.True(res2);
+        }
+
+        [Fact]
+        public void TrySetAgain_After_Expired_Should_Succed()
+        {
+            var key = Guid.NewGuid().ToString();
+            var v1 = "123456";
+            var res1 = _provider.TrySet<string>(key, v1, TimeSpan.FromSeconds(1));
+            Assert.True(res1);
+
+            System.Threading.Thread.Sleep(TimeSpan.FromSeconds(2));
+            var res2 = _provider.TrySet<string>(key, v1, TimeSpan.FromSeconds(5));
+            Assert.True(res2);
+        }
+
+        [Fact]
+        public void Set_Diff_Len_Value_Should_Succed()
+        {
+            var key = Guid.NewGuid().ToString();
+            var v1 = "1234567890";
+            var v2 = "12345";
+
+            _provider.Set<string>(key, v1, TimeSpan.FromSeconds(15));
+            var res1 = _provider.Get<string>(key);
+            Assert.Equal(v1, res1.Value);
+
+            _provider.Set<string>(key, v2, TimeSpan.FromSeconds(15));
+            var res2 = _provider.Get<string>(key);
+            Assert.Equal(v2, res2.Value);
+        }
     }   
 }