From e038a0838d749bc218877a2af8d5748b56a1421f Mon Sep 17 00:00:00 2001
From: Ferenc Czirok <ferenc@czirok.net>
Date: Thu, 12 Oct 2023 10:11:32 +0200
Subject: [PATCH] Service duplication fix (#224)

Fixes when multiple nuget packages or project references contain Blazored.LocalStorage and call AddBlazoredLocalStorage(). No error occurs if it is added more than once, but the services are only needed once.
---
 .../ServiceCollectionExtensions.cs            | 40 +++++----
 .../ServiceCollectionExtensionsTest.cs        | 81 +++++++++++++++++++
 2 files changed, 106 insertions(+), 15 deletions(-)
 create mode 100644 tests/Blazored.LocalStorage.Tests/LocalStorageServiceTests/ServiceCollectionExtensionsTest.cs

diff --git a/src/Blazored.LocalStorage/ServiceCollectionExtensions.cs b/src/Blazored.LocalStorage/ServiceCollectionExtensions.cs
index c561126..e59eb97 100644
--- a/src/Blazored.LocalStorage/ServiceCollectionExtensions.cs
+++ b/src/Blazored.LocalStorage/ServiceCollectionExtensions.cs
@@ -1,9 +1,12 @@
-using System;
+using System;
 using System.Diagnostics.CodeAnalysis;
+using System.Linq;
 using Blazored.LocalStorage.JsonConverters;
 using Blazored.LocalStorage.Serialization;
 using Blazored.LocalStorage.StorageOptions;
 using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.DependencyInjection.Extensions;
+using Microsoft.Extensions.Options;
 
 namespace Blazored.LocalStorage
 {
@@ -15,18 +18,22 @@ public static IServiceCollection AddBlazoredLocalStorage(this IServiceCollection
 
         public static IServiceCollection AddBlazoredLocalStorage(this IServiceCollection services, Action<LocalStorageOptions> configure)
         {
-            return services
-                .AddScoped<IJsonSerializer, SystemTextJsonSerializer>()
-                .AddScoped<IStorageProvider, BrowserStorageProvider>()
-                .AddScoped<ILocalStorageService, LocalStorageService>()
-                .AddScoped<ISyncLocalStorageService, LocalStorageService>()
-                .Configure<LocalStorageOptions>(configureOptions =>
+            services.TryAddScoped<IJsonSerializer, SystemTextJsonSerializer>();
+            services.TryAddScoped<IStorageProvider, BrowserStorageProvider>();
+            services.TryAddScoped<ILocalStorageService, LocalStorageService>();
+            services.TryAddScoped<ISyncLocalStorageService, LocalStorageService>();
+            if (services.All(serviceDescriptor => serviceDescriptor.ServiceType != typeof(IConfigureOptions<LocalStorageOptions>)))
+            {
+                services.Configure<LocalStorageOptions>(configureOptions =>
                 {
                     configure?.Invoke(configureOptions);
                     configureOptions.JsonSerializerOptions.Converters.Add(new TimespanJsonConverter());
                 });
+            }
+
+            return services;
         }
-        
+
         /// <summary>
         /// Registers the Blazored LocalStorage services as singletons. This should only be used in Blazor WebAssembly applications.
         /// Using this in Blazor Server applications will cause unexpected and potentially dangerous behaviour. 
@@ -34,7 +41,7 @@ public static IServiceCollection AddBlazoredLocalStorage(this IServiceCollection
         /// <returns></returns>
         public static IServiceCollection AddBlazoredLocalStorageAsSingleton(this IServiceCollection services)
             => AddBlazoredLocalStorageAsSingleton(services, null);
-        
+
         /// <summary>
         /// Registers the Blazored LocalStorage services as singletons. This should only be used in Blazor WebAssembly applications.
         /// Using this in Blazor Server applications will cause unexpected and potentially dangerous behaviour. 
@@ -44,16 +51,19 @@ public static IServiceCollection AddBlazoredLocalStorageAsSingleton(this IServic
         /// <returns></returns>
         public static IServiceCollection AddBlazoredLocalStorageAsSingleton(this IServiceCollection services, Action<LocalStorageOptions> configure)
         {
-            return services
-                .AddSingleton<IJsonSerializer, SystemTextJsonSerializer>()
-                .AddSingleton<IStorageProvider, BrowserStorageProvider>()
-                .AddSingleton<ILocalStorageService, LocalStorageService>()
-                .AddSingleton<ISyncLocalStorageService, LocalStorageService>()
-                .Configure<LocalStorageOptions>(configureOptions =>
+            services.TryAddSingleton<IJsonSerializer, SystemTextJsonSerializer>();
+            services.TryAddSingleton<IStorageProvider, BrowserStorageProvider>();
+            services.TryAddSingleton<ILocalStorageService, LocalStorageService>();
+            services.TryAddSingleton<ISyncLocalStorageService, LocalStorageService>();
+            if (services.All(serviceDescriptor => serviceDescriptor.ServiceType != typeof(IConfigureOptions<LocalStorageOptions>)))
+            {
+                services.Configure<LocalStorageOptions>(configureOptions =>
                 {
                     configure?.Invoke(configureOptions);
                     configureOptions.JsonSerializerOptions.Converters.Add(new TimespanJsonConverter());
                 });
+            }
+            return services;
         }
     }
 }
diff --git a/tests/Blazored.LocalStorage.Tests/LocalStorageServiceTests/ServiceCollectionExtensionsTest.cs b/tests/Blazored.LocalStorage.Tests/LocalStorageServiceTests/ServiceCollectionExtensionsTest.cs
new file mode 100644
index 0000000..73a21b4
--- /dev/null
+++ b/tests/Blazored.LocalStorage.Tests/LocalStorageServiceTests/ServiceCollectionExtensionsTest.cs
@@ -0,0 +1,81 @@
+using System;
+using System.Linq;
+using Blazored.LocalStorage.Serialization;
+using Blazored.LocalStorage.StorageOptions;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Options;
+using Xunit;
+
+namespace Blazored.LocalStorage.Tests.LocalStorageServiceTests;
+
+public class ServiceCollectionExtensionsTest
+{
+    [Fact]
+    public void Scoped()
+    {
+        // Arrange
+        var services = new ServiceCollection();
+
+        // Act
+        services.AddBlazoredLocalStorage();
+        services.AddBlazoredLocalStorage();
+        services.AddBlazoredLocalStorage();
+        services.AddBlazoredLocalStorage();
+
+        // Assert
+        AssertEqual(services, typeof(IJsonSerializer), typeof(SystemTextJsonSerializer), ServiceLifetime.Scoped);
+        AssertEqual(services, typeof(IStorageProvider), typeof(BrowserStorageProvider), ServiceLifetime.Scoped);
+        AssertEqual(services, typeof(ILocalStorageService), typeof(LocalStorageService), ServiceLifetime.Scoped);
+        AssertEqual(services, typeof(ISyncLocalStorageService), typeof(LocalStorageService), ServiceLifetime.Scoped);
+        AssertEqualConfigureOptions(services, typeof(IConfigureOptions<LocalStorageOptions>), ServiceLifetime.Singleton);
+    }
+
+    [Fact]
+    public void Singleton()
+    {
+        // Arrange
+        var services = new ServiceCollection();
+
+        // Act
+        services.AddBlazoredLocalStorageAsSingleton();
+        services.AddBlazoredLocalStorageAsSingleton();
+        services.AddBlazoredLocalStorageAsSingleton();
+        services.AddBlazoredLocalStorageAsSingleton();
+
+        // Assert
+        AssertEqual(services, typeof(IJsonSerializer), typeof(SystemTextJsonSerializer), ServiceLifetime.Singleton);
+        AssertEqual(services, typeof(IStorageProvider), typeof(BrowserStorageProvider), ServiceLifetime.Singleton);
+        AssertEqual(services, typeof(ILocalStorageService), typeof(LocalStorageService), ServiceLifetime.Singleton);
+        AssertEqual(services, typeof(ISyncLocalStorageService), typeof(LocalStorageService), ServiceLifetime.Singleton);
+        AssertEqualConfigureOptions(services, typeof(IConfigureOptions<LocalStorageOptions>), ServiceLifetime.Singleton);
+    }
+
+
+    static void AssertEqual(
+        IServiceCollection services,
+        Type serviceType,
+        Type implementationType,
+        ServiceLifetime serviceLifetime
+        )
+    {
+        var descriptors = services.Where(serviceDescriptor => serviceDescriptor.ServiceType == serviceType).ToArray();
+        Assert.Single(descriptors);
+        var descriptor = descriptors.Single();
+        Assert.Equal(serviceType, descriptor.ServiceType);
+        Assert.Equal(implementationType, descriptor.ImplementationType);
+        Assert.Equal(serviceLifetime, descriptor.Lifetime);
+    }
+
+    static void AssertEqualConfigureOptions(
+        IServiceCollection services,
+        Type serviceType,
+        ServiceLifetime serviceLifetime
+    )
+    {
+        var descriptors = services.Where(serviceDescriptor => serviceDescriptor.ServiceType == serviceType).ToArray();
+        Assert.Single(descriptors);
+        var descriptor = descriptors.Single();
+        Assert.Equal(serviceType, descriptor.ServiceType);
+        Assert.Equal(serviceLifetime, descriptor.Lifetime);
+    }
+}