Add unit test for `IAbpHostEnvironment`.

framework/test/Volo.Abp.Core.Tests/Volo/Abp/AbpApplication_Initialize_Tests.cs

@@ -4,6 +4,7 @@ using System.Reflection;
 using System.Threading.Tasks;
 using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Hosting;
 using NSubstitute;
 using Shouldly;
 using Volo.Abp.DependencyInjection;
@@ -204,6 +205,37 @@ public class AbpApplication_Initialize_Tests
         }
     }
 
+    [Fact]
+    public void Should_Set_And_Get_Environment()
+    {
+        // Default environment is Production
+        using (var application = AbpApplicationFactory.Create<IndependentEmptyModule>())
+        {
+            var abpHostEnvironment = application.Services.GetSingletonInstance<IAbpHostEnvironment>();
+            abpHostEnvironment.EnvironmentName.ShouldBe(Environments.Production);
+
+            application.Initialize();
+
+            abpHostEnvironment = application.ServiceProvider.GetRequiredService<IAbpHostEnvironment>();
+            abpHostEnvironment.EnvironmentName.ShouldBe(Environments.Production);
+        }
+
+        // Set environment
+        using (var application = AbpApplicationFactory.Create<IndependentEmptyModule>(options =>
+               {
+                   options.Environment = Environments.Staging;
+               }))
+        {
+            var abpHostEnvironment = application.Services.GetSingletonInstance<IAbpHostEnvironment>();
+            abpHostEnvironment.EnvironmentName.ShouldBe(Environments.Staging);
+
+            application.Initialize();
+
+            abpHostEnvironment = application.ServiceProvider.GetRequiredService<IAbpHostEnvironment>();
+            abpHostEnvironment.EnvironmentName.ShouldBe(Environments.Staging);
+        }
+    }
+
     [Fact]
     public async Task Should_Resolve_Root_Service_Provider()
     {