Add a little clarity

cmd/transpile/main.go

@@ -32,17 +32,21 @@ func nothing() error {
 	return nil
 }
 
+func usage(w io.Writer) {
+	fmt.Fprintln(w, "Usage: transpile COMMAND [flags]")
+	fmt.Fprintln(w, "")
+	fmt.Fprintln(w, " mothball: Compile a mothball")
+	fmt.Fprintln(w, " inventory: Show category inventory")
+	fmt.Fprintln(w, " open: Open a file for a puzzle")
+	fmt.Fprintln(w, " answer: Check correctness of an answer")
+}
+
 // ParseArgs parses arguments and runs the appropriate action.
 func (t *T) ParseArgs() (Command, error) {
 	var cmd Command
 
 	if len(t.Args) == 1 {
-		fmt.Fprintln(t.Stderr, "Usage: transpile COMMAND [flags]")
-		fmt.Fprintln(t.Stderr, "")
-		fmt.Fprintln(t.Stderr, " mothball: Compile a mothball")
-		fmt.Fprintln(t.Stderr, " inventory: Show category inventory")
-		fmt.Fprintln(t.Stderr, " open: Open a file for a puzzle")
-		fmt.Fprintln(t.Stderr, " answer: Check correctness of an answer")
+		usage(t.Stderr)
 		return nothing, nil
 	}
 
@@ -60,7 +64,11 @@ func (t *T) ParseArgs() (Command, error) {
 	case "answer":
 		flags.StringVar(&t.answer, "answer", "", "Answer to check")
 		cmd = t.CheckAnswer
+	case "help":
+		usage(t.Stderr)
+		return nothing, nil
 	default:
+		usage(t.Stderr)
 		return nothing, fmt.Errorf("%s is not a valid command", t.Args[1])
 	}
 
@@ -69,6 +77,7 @@ func (t *T) ParseArgs() (Command, error) {
 		return nothing, err
 	}
 	if *directory != "" {
+		log.Println(*directory)
 		t.fs = afero.NewBasePathFs(t.BaseFs, *directory)
 	} else {
 		t.fs = t.BaseFs
@@ -101,6 +110,7 @@ func (t *T) PrintInventory() error {
 }
 
 // DumpFile writes a file to the writer.
+// BUG(neale): The "open" and "answer" actions don't work on categories with an "mkcategory" executable.
 func (t *T) DumpFile() error {
 	puzzle := transpile.NewFsPuzzle(t.fs)
 
@@ -160,6 +170,7 @@ func main() {
 		Stdout: os.Stdout,
 		Stderr: os.Stderr,
 		Args:   os.Args,
+		BaseFs: afero.NewOsFs(),
 	}
 	cmd, err := t.ParseArgs()
 	if err != nil {

pkg/transpile/category.go

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"context"
 	"encoding/json"
+	"fmt"
 	"log"
 	"os/exec"
 	"path"
@@ -134,7 +135,9 @@ func (c FsCommandCategory) run(command string, args ...string) ([]byte, error) {
 // Inventory returns a list of point values for this category.
 func (c FsCommandCategory) Inventory() ([]int, error) {
 	stdout, err := c.run("inventory")
-	if err != nil {
+	if exerr, ok := err.(*exec.ExitError); ok {
+		return nil, fmt.Errorf("inventory: %s: %s", err, string(exerr.Stderr))
+	} else if err != nil {
 		return nil, err
 	}
 

pkg/transpile/inventory.go

@@ -29,7 +29,8 @@ func FsInventory(fs afero.Fs) (Inventory, error) {
 			c := NewFsCategory(fs, name)
 			puzzles, err := c.Inventory()
 			if err != nil {
-				return nil, err
+				log.Printf("Inventory: %s: %s", name, err)
+				continue
 			}
 			sort.Ints(puzzles)
 			inv[name] = puzzles