1 files changed, 163 insertions, 0 deletions
diff --git a/runner/run_test.go b/runner/run_test.go
new file mode 100644
index 0000000..d6c1500
--- /dev/null
+++ b/runner/run_test.go
@@ -0,0 +1,163 @@
+package runner_test
+
+import (
+	"bytes"
+	"context"
+	"errors"
+	"flag"
+	"io"
+	"reflect"
+	"strings"
+	"testing"
+
+	"go.sudomsg.com/kit/runner"
+)
+
+func TestCommandSet_Run(t *testing.T) {
+	t.Run("Dispatch", func(t *testing.T) {
+		t.Parallel()
+
+		ctx := t.Context()
+
+		var called bool
+		cs := &runner.CommandSet{
+			FlagSet: flag.NewFlagSet("test", flag.ContinueOnError),
+		}
+		cs.SetOutput(io.Discard)
+
+		cs.AddSubcommand("foo", "foo command", func(ctx context.Context, cs *runner.CommandSet, args []string) error {
+			called = true
+			if !reflect.DeepEqual(args, []string{"bar", "baz"}) {
+				t.Fatalf("callback got args %v, want [bar baz]", args)
+			}
+			if gotName := cs.Name(); gotName != "foo" {
+				t.Fatalf("sub FlagSet name = %q, want %q", gotName, "foo")
+			}
+
+			return nil
+		})
+
+		err := cs.Run(ctx, []string{"foo", "bar", "baz"})
+		if err != nil {
+			t.Fatalf("unexpected error: %v", err)
+		}
+		if !called {
+			t.Fatal("expected foo subcommand to be called")
+		}
+	})
+
+	t.Run("Recursive Dispatch", func(t *testing.T) {
+		t.Parallel()
+
+		ctx := t.Context()
+
+		var called bool
+		cs := &runner.CommandSet{
+			FlagSet: flag.NewFlagSet("test", flag.ContinueOnError),
+		}
+		cs.SetOutput(io.Discard)
+
+		cs.AddSubcommand("foo", "foo command", func(ctx context.Context, cs *runner.CommandSet, args []string) error {
+			cs.AddSubcommand("bar", "bar command", func(ctx context.Context, cs *runner.CommandSet, args []string) error {
+				called = true
+				if !reflect.DeepEqual(args, []string{"baz"}) {
+					t.Fatalf("callback got args %v, want [bar baz]", args)
+				}
+				if gotName := cs.Name(); gotName != "bar" {
+					t.Fatalf("sub FlagSet name = %q, want %q", gotName, "foo")
+				}
+				return nil
+			})
+			return cs.Run(ctx, args)
+		})
+
+		err := cs.Run(ctx, []string{"foo", "bar", "baz"})
+		if err != nil {
+			t.Fatalf("unexpected error: %v", err)
+		}
+		if !called {
+			t.Fatal("expected foo subcommand to be called")
+		}
+
+	})
+
+	t.Run("No Subcommand", func(t *testing.T) {
+		t.Parallel()
+
+		ctx := t.Context()
+		var buf bytes.Buffer
+
+		cs := &runner.CommandSet{
+			FlagSet: flag.NewFlagSet("test", flag.ContinueOnError),
+		}
+		cs.SetOutput(&buf)
+
+		err := cs.Run(ctx, []string{})
+		if err == nil {
+			t.Fatal("expected error, got nil")
+		}
+		var ue runner.UsageError
+		if !errors.As(err, &ue) {
+			t.Fatalf("expected UsageError, got %T", err)
+		}
+		if !strings.Contains(buf.String(), "Missing Subcommand") {
+			t.Errorf("expected help output to mention missing subcommand, got %q", buf.String())
+		}
+	})
+
+	t.Run("Invalid Subcommand", func(t *testing.T) {
+		t.Parallel()
+
+		ctx := t.Context()
+		var buf bytes.Buffer
+
+		cs := &runner.CommandSet{
+			FlagSet: flag.NewFlagSet("test", flag.ContinueOnError),
+		}
+		cs.SetOutput(&buf)
+
+		cs.AddSubcommand("foo", "bar", func(ctx context.Context, cs *runner.CommandSet, args []string) error {
+			t.Fatalf("foo command called")
+			return nil
+		})
+
+		err := cs.Run(ctx, []string{"nope"})
+		if err == nil {
+			t.Fatal("expected error, got nil")
+		}
+
+		var ue runner.UsageError
+		if !errors.As(err, &ue) {
+			t.Fatalf("expected UsageError, got %T", err)
+		}
+		if !strings.Contains(buf.String(), "Invalid Subcommand") {
+			t.Errorf("expected help output to mention invalid subcommand, got %q", buf.String())
+		}
+	})
+
+	t.Run("Invalid Flags", func(t *testing.T) {
+		t.Parallel()
+
+		ctx := t.Context()
+		var buf bytes.Buffer
+
+		cs := &runner.CommandSet{
+			FlagSet: flag.NewFlagSet("test", flag.ContinueOnError),
+		}
+		cs.SetOutput(&buf)
+
+		cs.AddSubcommand("foo", "foo command", func(ctx context.Context, cs *runner.CommandSet, args []string) error {
+			return cs.Run(ctx, args)
+		})
+
+		err := cs.Run(ctx, []string{"foo", "-bar"})
+		if err == nil {
+			t.Fatal("expected error, got nil")
+		}
+
+		var ue runner.UsageError
+		if !errors.As(err, &ue) {
+			t.Fatalf("expected UsageError, got %T", err)
+		}
+	})
+}