refactor(INetworkMonitor): update return type nullable NetworkMonitorState (#6417)

* refactor: 更改返回值为可为空对象

* test: 更新单元测试

Author: ArgoZhang

src/BootstrapBlazor/Services/DefaultNetworkMonitorService.cs

@@ -34,10 +34,10 @@ public DefaultNetowrkMonitorService(IJSRuntime jsRuntime)
     /// <summary>
     /// <inheritdoc/>
     /// </summary>
-    public async Task<NetworkMonitorState> GetNetworkMonitorState(CancellationToken token = default)
+    public async Task<NetworkMonitorState?> GetNetworkMonitorState(CancellationToken token = default)
     {
         _module ??= await LoadModule();
-        return await _module.InvokeAsync<NetworkMonitorState?>("getNetworkInfo", token) ?? new();
+        return await _module.InvokeAsync<NetworkMonitorState?>("getNetworkInfo", token);
     }
 
     /// <summary>

src/BootstrapBlazor/Services/INetworkMonitorService.cs

@@ -16,7 +16,7 @@ public interface INetworkMonitorService
     /// <param name="token">A cancellation token that can be used to cancel the operation.</param>
     /// <returns>A task representing the asynchronous operation. The task result contains the current <see
     /// cref="NetworkMonitorState"/>.</returns>
-    Task<NetworkMonitorState> GetNetworkMonitorState(CancellationToken token = default);
+    Task<NetworkMonitorState?> GetNetworkMonitorState(CancellationToken token = default);
 
     /// <summary>
     /// Registers a callback to be invoked when the network monitor state changes.

test/UnitTest/Services/DefaultNetworkMonitorServiceTest.cs

@@ -18,6 +18,7 @@ public async Task GetNetworkMonitorState_Ok()
         });
         var service = Context.Services.GetRequiredService<INetworkMonitorService>();
         var state = await service.GetNetworkMonitorState(CancellationToken.None);
+        Assert.NotNull(state);
         Assert.Equal("4g", state.NetworkType);
         Assert.Equal(10, state.Downlink);
         Assert.Equal(100, state.RTT);

test/UnitTest/Services/TcpSocketFactoryTest.cs

@@ -637,7 +637,7 @@ public async Task DelimiterDataPackageHandler_Ok()
         var ex = Assert.Throws<ArgumentNullException>(() => new DelimiterDataPackageHandler(string.Empty));
         Assert.NotNull(ex);
 
-        ex = Assert.Throws<ArgumentNullException>(() => new DelimiterDataPackageHandler((byte[])null!));
+        ex = Assert.Throws<ArgumentNullException>(() => new DelimiterDataPackageHandler(null!));
         Assert.NotNull(ex);
     }