Fix #85 - lower priority of resolving AdditionalServices after most built-in services

Author: natemcmaster

CHANGELOG.md

@@ -6,6 +6,7 @@ Bug fixes:
 
  - Don't assign option and argument options if no value was provided, preserving the default CLR value unless there is user-input.
  - Fix ShowHint() to use ShortName or SymbolName if OptionHelp.LongName is not set
+ - Fix [#85](https://github.com/natemcmaster/CommandLineUtils/issues/85) - lower priority of resolving AdditionalServices after most built-in services
 
 Minor improvements:
 

src/CommandLineUtils/CommandLineApplication.cs

@@ -922,20 +922,8 @@ public object GetService(Type serviceType)
                     return _parent;
                 }
 
-                if (_parent.AdditionalServices != null)
-                {
-                    var retVal = _parent.AdditionalServices.GetService(serviceType);
-                    if (retVal != null)
-                    {
-                        return retVal;
-                    }
-                }
-
-                if (serviceType == typeof(IConsole))
-                {
-                    return _parent._context.Console;
-                }
-
+                // prefer this type before AdditionalServces because it is common for service containers to automatically
+                // create IEnumerable<T> to allow registration of multiple services
                 if (serviceType == typeof(IEnumerable<CommandOption>))
                 {
                     return _parent.GetOptions();
@@ -961,6 +949,22 @@ public object GetService(Type serviceType)
                     return accessor.GetModel();
                 }
 
+                if (_parent.AdditionalServices != null)
+                {
+                    var retVal = _parent.AdditionalServices.GetService(serviceType);
+                    if (retVal != null)
+                    {
+                        return retVal;
+                    }
+                }
+
+                // Resolve this after AdditionalServices to support overriding IConsole from a custom service container
+                // may be overridden
+                if (serviceType == typeof(IConsole))
+                {
+                    return _parent._context.Console;
+                }
+
                 return null;
             }
         }

test/CommandLineUtils.Tests/ConstructorInjectionConventionTests.cs

@@ -3,6 +3,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Linq;
 using Microsoft.Extensions.DependencyInjection;
 using Xunit;
 using Xunit.Abstractions;
@@ -50,6 +51,40 @@ public void ItSupportsCustomServices()
             Assert.Same(testConsole, app.Model.Console);
         }
 
+        private class OptionsCtorCommand
+        {
+            private readonly IEnumerable<CommandOption> _options;
+            private readonly IEnumerable<CommandArgument> _arguments;
+
+            public OptionsCtorCommand(IEnumerable<CommandOption> options, IEnumerable<CommandArgument> arguments)
+            {
+                _options = options;
+                _arguments = arguments;
+            }
+
+            public int GetOptionCount() => _options.Count();
+            public int GetArgCount() => _arguments.Count();
+
+            [Option]
+            public string Opt { get; }
+
+            [Argument(0)]
+            public string Arg { get; }
+        }
+
+        [Fact]
+        public void ItPrefersIEnumOfOptionsFromUs()
+        {
+            var app = new CommandLineApplication<OptionsCtorCommand>();
+            var services = new ServiceCollection().BuildServiceProvider();
+            app.Conventions.UseDefaultConventions().UseConstructorInjection(services);
+            app.Parse();
+            Assert.Empty(services.GetServices<IEnumerable<CommandOption>>());
+            Assert.Empty(services.GetServices<IEnumerable<CommandArgument>>());
+            Assert.Equal(1, app.Model.GetOptionCount());
+            Assert.Equal(1, app.Model.GetArgCount());
+        }
+
         [Subcommand("test", typeof(Child))]
         private class Parent
         {