fix: cli defaults (#74)

src/dotnet-affected/AffectedCli.cs

@@ -15,6 +15,7 @@ internal static class AffectedCli
         public static CommandLineBuilder CreateAffectedCommandLineBuilder()
         {
             return new CommandLineBuilder(new AffectedRootCommand())
+                .UseDefaults()
                 .UseRenderingErrorHandler(new Dictionary<Type, RenderingErrorConfig>
                 {
                     [typeof(NoChangesException)] = new(AffectedExitCodes.NothingChanged, new NoChangesView()),

src/dotnet-affected/Commands/AffectedRootCommand.cs

@@ -15,6 +15,7 @@ internal class AffectedRootCommand : RootCommand
         public AffectedRootCommand()
             : base("Determines which projects are affected by a set of changes.")
         {
+            this.Name = "dotnet-affected";
             this.AddCommand(new DescribeCommand());
 
             this.AddGlobalOption(AffectedGlobalOptions.RepositoryPathOptions);

test/dotnet-affected.Tests/AffectedCliDefaultsTests.cs

@@ -0,0 +1,31 @@
+using System.Threading.Tasks;
+using Xunit;
+using Xunit.Abstractions;
+
+namespace Affected.Cli.Tests
+{
+    /// <summary>
+    /// Tests for the public API.
+    /// Ensures that the CLI implements common stuff like --help
+    /// </summary>
+    public class AffectedCliDefaultsTests : BaseInvocationTest
+    {
+        public AffectedCliDefaultsTests(ITestOutputHelper helper)
+            : base(helper)
+        {
+        }
+
+        [Fact]
+        public async Task When_help_should_output_help()
+        {
+            var (output, exitCode) =
+                await this.InvokeAsync("--help");
+
+            Assert.Equal(0, exitCode);
+
+            Assert.Contains("Determines which projects are affected by a set of changes.", output);
+            Assert.Contains("Usage:", output);
+            Assert.Contains("dotnet-affected [command] [options]", output);
+        }
+    }
+}