Added more tests for the ILogger docs

Author: JonPSmith

Test/UnitTests/TestDataLayer/TestMyLoggerProviderActionOut.cs

@@ -1,11 +1,14 @@
 // Copyright (c) 2020 Jon P Smith, GitHub: JonPSmith, web: http://www.thereformedprogrammer.net/
 // Licensed under MIT license. See License.txt in the project root for license information.
 
+using System;
 using System.Collections.Generic;
 using System.Linq;
+using System.Runtime.InteropServices.ComTypes;
 using DataLayer.BookApp.EfCode;
 using Microsoft.Data.Sqlite;
 using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Logging;
 using Test.Helpers;
 using TestSupport.EfHelpers;
@@ -24,6 +27,118 @@ public TestMyLoggerProviderActionOut(ITestOutputHelper output)
             _output = output;
         }
 
+        class MyService
+        {
+            private readonly ILogger _logger;
+
+            public MyService(ILogger<MyService> logger)
+            {
+                _logger = logger;
+            }
+
+            public void AddInfoLog()
+            {
+                _logger.LogInformation("This is a log");
+            }
+        }
+
+        [Fact]
+        public void TestDependencyInjectionFailIfNoLogger()
+        {
+            //SETUP
+            var services = new ServiceCollection();
+            services.AddSingleton<MyService>();
+
+            //ATTEMPT
+            var serviceProvider = services.BuildServiceProvider();
+            var ex = Assert.Throws<InvalidOperationException>(() => serviceProvider.GetService<MyService>());
+
+            //VERIFY
+            ex.Message.ShouldStartWith("Unable to resolve service");
+        }
+
+        [Fact]
+        public void TestAddLoggerInDependencyInjection()
+        {
+            //SETUP
+            var services = new ServiceCollection();
+            services.AddTransient<MyService>();
+            services.AddLogging();
+
+            //ATTEMPT
+            var serviceProvider = services.BuildServiceProvider();
+            var myServiceDI = serviceProvider.GetService<MyService>();
+
+            //VERIFY
+            myServiceDI.ShouldNotBeNull();
+            myServiceDI.AddInfoLog();
+        }
+
+        [Fact]
+        public void TestAddingLoggerInDependencyInjection()
+        {
+            //SETUP
+            var logs = new List<LogOutput>();
+            var services = new ServiceCollection();
+            services.AddTransient<MyService>();
+            services.AddSingleton<ILogger<MyService>>(x =>
+                new LoggerFactory(
+                        new[] { new MyLoggerProviderActionOut(l => logs.Add(l)) })
+                    .CreateLogger<MyService>());
+
+            //ATTEMPT
+            var serviceProvider = services.BuildServiceProvider();
+            var myServiceDI = serviceProvider.GetRequiredService<MyService>();
+
+            //VERIFY
+            logs.Count.ShouldEqual(0);
+            myServiceDI.AddInfoLog();
+            logs.Count.ShouldEqual(1);
+            _output.WriteLine(logs.Single().ToString());
+        }
+
+        class MyOtherService
+        {
+            private readonly ILogger _logger;
+
+            public MyOtherService(ILogger<MyOtherService> logger)
+            {
+                _logger = logger;
+            }
+
+            public void AddInfoLog()
+            {
+                _logger.LogInformation("This is a log");
+            }
+        }
+
+        [Fact]
+        public void TestAddingLoggerInDependencyInjectionWithAddLogging()
+        {
+            //SETUP
+            var logs = new List<LogOutput>();
+            var services = new ServiceCollection();
+            services.AddLogging();
+            services.AddTransient<MyService>();
+            services.AddTransient<MyOtherService>();
+            services.AddSingleton<ILogger<MyService>>(x =>
+                new LoggerFactory(
+                        new[] { new MyLoggerProviderActionOut(l => logs.Add(l)) })
+                    .CreateLogger<MyService>());
+
+            //ATTEMPT
+            var serviceProvider = services.BuildServiceProvider();
+            var myServiceDI = serviceProvider.GetRequiredService<MyService>();
+            var myOtherService = serviceProvider.GetRequiredService<MyOtherService>();
+
+            //VERIFY
+            logs.Count.ShouldEqual(0);
+            myServiceDI.AddInfoLog();
+            logs.Count.ShouldEqual(1);
+            _output.WriteLine(logs.Single().ToString());
+            myOtherService.AddInfoLog();
+        }
+
         [Fact]
         public void TestDecodeMessageNotSensitiveLogging()
         {