From 0418877db0d6e6b6712fe106ac8a9f294d1741eb Mon Sep 17 00:00:00 2001
From: Neale Pickett <neale@lanl.gov>
Date: Fri, 28 Aug 2020 17:41:17 -0600
Subject: [PATCH] transpiler work

---
 cmd/transpile/category.go    | 145 ++++++------------------------
 cmd/transpile/go.mod         |   9 --
 cmd/transpile/go.sum         |   7 --
 cmd/transpile/main.go        | 167 +++++++++++++++++++++++------------
 cmd/transpile/main_test.go   |  88 ++++++++++++++++++
 cmd/transpile/puzzle.go      | 145 ++++++++++++++++++++----------
 cmd/transpile/puzzle_test.go |  45 ++++++++++
 7 files changed, 367 insertions(+), 239 deletions(-)
 delete mode 100644 cmd/transpile/go.mod
 delete mode 100644 cmd/transpile/go.sum
 create mode 100644 cmd/transpile/main_test.go
 create mode 100644 cmd/transpile/puzzle_test.go

diff --git a/cmd/transpile/category.go b/cmd/transpile/category.go
index 3f303c3..42a214d 100644
--- a/cmd/transpile/category.go
+++ b/cmd/transpile/category.go
@@ -1,138 +1,47 @@
 package main
 
 import (
-	"os"
-	"fmt"
 	"log"
-	"path/filepath"
-	"hash/fnv"
-	"encoding/binary"
-	"encoding/json"
-	"encoding/hex"
 	"strconv"
-	"math/rand"
-	"context"
-	"time"
-	"os/exec"
-	"bytes"
+
+	"github.com/spf13/afero"
 )
 
-
-type PuzzleEntry struct {
-	Id string
-	Points int
-	Puzzle Puzzle
-}
-
-func PrngOfStrings(input ...string) (*rand.Rand) {
-	hasher := fnv.New64()
-	for _, s := range input {
-		fmt.Fprint(hasher, s, "\n")
+// NewCategory returns a new category for the given path in the given fs.
+func NewCategory(fs afero.Fs, cat string) Category {
+	return Category{
+		Fs: afero.NewBasePathFs(fs, cat),
 	}
-	seed := binary.BigEndian.Uint64(hasher.Sum(nil))
-	source := rand.NewSource(int64(seed))
-	return rand.New(source)
 }
 
+// Category represents an on-disk category.
+type Category struct {
+	afero.Fs
+}
 
-func runPuzzleGen(puzzlePath string, seed string) (*Puzzle, error) {
-	ctx, cancel := context.WithTimeout(context.Background(), 2*time.Second)
-	defer cancel()
-	
-	cmd := exec.CommandContext(ctx, puzzlePath)
-	cmd.Env = append(
-		os.Environ(),
-		fmt.Sprintf("MOTH_PUZZLE_SEED=%s", seed),
-	)
-	stdout, err := cmd.Output()
+// Puzzles returns a list of puzzle values.
+func (c Category) Puzzles() ([]int, error) {
+	puzzleEntries, err := afero.ReadDir(c, ".")
 	if err != nil {
 		return nil, err
 	}
-	
-	jsdec := json.NewDecoder(bytes.NewReader(stdout))
-	jsdec.DisallowUnknownFields()
-	puzzle := new(Puzzle)
-	err = jsdec.Decode(puzzle)
-	if err != nil {
-		return nil, err
-	}
-	
-	return puzzle, nil
-}
 
-func ParsePuzzle(puzzlePath string, puzzleSeed string) (*Puzzle, error) {
-	var puzzle *Puzzle
-
-	// Try the .moth file first
-	puzzleMothPath := filepath.Join(puzzlePath, "puzzle.moth")
-	puzzleFd, err := os.Open(puzzleMothPath)
-	if err == nil {
-		defer puzzleFd.Close()
-		puzzle, err = ParseMoth(puzzleFd)
-		if err != nil {
-			return nil, err
-		}
-	} else if os.IsNotExist(err) {
-		var genErr error
-		
-		puzzleGenPath := filepath.Join(puzzlePath, "mkpuzzle")
-		puzzle, genErr = runPuzzleGen(puzzleGenPath, puzzlePath)
-		if genErr != nil {
-			bigErr := fmt.Errorf(
-				"%v; (%s: %v)",
-				genErr,
-				filepath.Base(puzzleMothPath), err,
-			)
-			return nil, bigErr
-		}
-	} else {
-		return nil, err
-	}
-	
-	return puzzle, nil
-}
-
-
-func ParseCategory(categoryPath string, seed string) ([]PuzzleEntry, error) {
-	categoryFd, err := os.Open(categoryPath)
-	if err != nil {
-		return nil, err
-	}
-	defer categoryFd.Close()
-	
-	puzzleDirs, err := categoryFd.Readdirnames(0)
-	if err != nil {
-		return nil, err
-	}
-	
-	puzzleEntries := make([]PuzzleEntry, 0, len(puzzleDirs))
-	for _, puzzleDir := range puzzleDirs {
-		puzzlePath := filepath.Join(categoryPath, puzzleDir)
-		puzzleSeed := fmt.Sprintf("%s/%s", seed, puzzleDir)
-		puzzle, err := ParsePuzzle(puzzlePath, puzzleSeed)
-		if err != nil {
-			log.Printf("Skipping %s: %v", puzzlePath, err)
+	puzzles := make([]int, 0, len(puzzleEntries))
+	for _, ent := range puzzleEntries {
+		if !ent.IsDir() {
 			continue
 		}
-		
-		// Determine point value from directory name
-		points, err := strconv.Atoi(puzzleDir)
-		if err != nil {
-			return nil, err
+		if points, err := strconv.Atoi(ent.Name()); err != nil {
+			log.Println("Skipping non-numeric directory", ent.Name())
+			continue
+		} else {
+			puzzles = append(puzzles, points)
 		}
-
-		// Create a category entry for this
-		prng := PrngOfStrings(puzzlePath)
-		idBytes := make([]byte, 16)
-		prng.Read(idBytes)
-		id := hex.EncodeToString(idBytes)
-		puzzleEntry := PuzzleEntry{
-			Id: id,
-			Puzzle: *puzzle,
-			Points: points,
-		}
-		puzzleEntries = append(puzzleEntries, puzzleEntry)
 	}
-	
-	return puzzleEntries, nil
+	return puzzles, nil
+}
+
+// Puzzle returns the Puzzle associated with points.
+func (c Category) Puzzle(points int) (*Puzzle, error) {
+	return NewPuzzle(c.Fs, points)
 }
diff --git a/cmd/transpile/go.mod b/cmd/transpile/go.mod
deleted file mode 100644
index cb38492..0000000
--- a/cmd/transpile/go.mod
+++ /dev/null
@@ -1,9 +0,0 @@
-module github.com/russross/blackfriday/v2
-
-go 1.13
-
-require (
-	github.com/russross/blackfriday v2.0.0+incompatible
-	github.com/shurcooL/sanitized_anchor_name v1.0.0 // indirect
-	gopkg.in/yaml.v2 v2.3.0
-)
diff --git a/cmd/transpile/go.sum b/cmd/transpile/go.sum
deleted file mode 100644
index 8ee6ac9..0000000
--- a/cmd/transpile/go.sum
+++ /dev/null
@@ -1,7 +0,0 @@
-github.com/russross/blackfriday v2.0.0+incompatible h1:cBXrhZNUf9C+La9/YpS+UHpUT8YD6Td9ZMSU9APFcsk=
-github.com/russross/blackfriday v2.0.0+incompatible/go.mod h1:JO/DiYxRf+HjHt06OyowR9PTA263kcR/rfWxYHBV53g=
-github.com/shurcooL/sanitized_anchor_name v1.0.0 h1:PdmoCO6wvbs+7yrJyMORt4/BmY5IYyJwS/kOiWx8mHo=
-github.com/shurcooL/sanitized_anchor_name v1.0.0/go.mod h1:1NzhyTcUVG4SuEtjjoZeVRXNmyL/1OwPU0+IJeTBvfc=
-gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
-gopkg.in/yaml.v2 v2.3.0 h1:clyUAQHOM3G0M3f5vQj7LuJrETvjVot3Z5el9nffUtU=
-gopkg.in/yaml.v2 v2.3.0/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
diff --git a/cmd/transpile/main.go b/cmd/transpile/main.go
index 44d05fa..db2b0df 100644
--- a/cmd/transpile/main.go
+++ b/cmd/transpile/main.go
@@ -1,74 +1,125 @@
 package main
 
 import (
-	"flag"
 	"encoding/json"
-	"path/filepath"
-	"strconv"
-	"strings"
-	"os"
-	"log"
+	"flag"
 	"fmt"
+	"io"
+	"log"
+	"os"
+	"sort"
+
+	"github.com/GoBike/envflag"
+	"github.com/spf13/afero"
 )
 
-func seedJoin(parts ...string) string {
-	return strings.Join(parts, "::")
+// T contains everything required for a transpilation invocation (across the nation).
+type T struct {
+	// What action to take
+	w        io.Writer
+	Cat      string
+	Points   int
+	Answer   string
+	Filename string
+	Fs       afero.Fs
 }
 
-func usage() {
-	out := flag.CommandLine.Output()
-	name := flag.CommandLine.Name()
-	fmt.Fprintf(out, "Usage: %s [OPTION]... CATEGORY [PUZZLE [FILENAME]]\n", name)
-	fmt.Fprintf(out, "\n")
-	fmt.Fprintf(out, "Transpile CATEGORY, or provide individual category components.\n")
-	fmt.Fprintf(out, "If PUZZLE is provided, only transpile the given puzzle.\n")
-	fmt.Fprintf(out, "If FILENAME is provided, output provided file.\n")
-	flag.PrintDefaults()
+// NewCategory returns a new Category as specified by cat.
+func (t *T) NewCategory(cat string) Category {
+	return NewCategory(t.Fs, cat)
+}
+
+// ParseArgs parses command-line arguments into T, returning the action to take
+func (t *T) ParseArgs() string {
+	action := flag.String("action", "inventory", "Action to take: must be 'inventory', 'open', 'answer', or 'mothball'")
+	flag.StringVar(&t.Cat, "cat", "", "Puzzle category")
+	flag.IntVar(&t.Points, "points", 0, "Puzzle point value")
+	flag.StringVar(&t.Answer, "answer", "", "Answer to check for correctness, for 'answer' action")
+	flag.StringVar(&t.Filename, "filename", "", "Filename, for 'open' action")
+	basedir := flag.String("basedir", ".", "Base directory containing all puzzles")
+	envflag.Parse()
+
+	osfs := afero.NewOsFs()
+	t.Fs = afero.NewBasePathFs(osfs, *basedir)
+
+	return *action
+}
+
+// Handle performs the requested action
+func (t *T) Handle(action string) error {
+	switch action {
+	case "inventory":
+		return t.PrintInventory()
+	case "open":
+		return t.Open()
+	default:
+		return fmt.Errorf("Unimplemented action: %s", action)
+	}
+}
+
+// PrintInventory prints a puzzle inventory to stdout
+func (t *T) PrintInventory() error {
+	dirEnts, err := afero.ReadDir(t.Fs, ".")
+	if err != nil {
+		return err
+	}
+	for _, ent := range dirEnts {
+		if ent.IsDir() {
+			c := t.NewCategory(ent.Name())
+			if puzzles, err := c.Puzzles(); err != nil {
+				log.Print(err)
+				continue
+			} else {
+				fmt.Fprint(t.w, ent.Name())
+				sort.Ints(puzzles)
+				for _, points := range puzzles {
+					fmt.Fprint(t.w, " ")
+					fmt.Fprint(t.w, points)
+				}
+				fmt.Fprintln(t.w)
+			}
+		}
+	}
+	return nil
+}
+
+// Open writes a file to the writer.
+func (t *T) Open() error {
+	c := t.NewCategory(t.Cat)
+	p, err := c.Puzzle(t.Points)
+	if err != nil {
+		return err
+	}
+
+	switch t.Filename {
+	case "puzzle.json", "":
+		jp, err := json.Marshal(p)
+		if err != nil {
+			return err
+		}
+		t.w.Write(jp)
+	default:
+		f, err := p.Open(t.Filename)
+		if err != nil {
+			return err
+		}
+		defer f.Close()
+		if _, err := io.Copy(t.w, f); err != nil {
+			return err
+		}
+	}
+
+	return nil
 }
 
 func main() {
 	// XXX: Convert puzzle.py to standalone thingies
-	
-	flag.Usage = usage
-	
-	points := flag.Int("points", 0, "Transpile only this point value puzzle")
-	mothball := flag.Bool("mothball", false, "Generate a mothball")
-	flag.Parse()
 
-	baseSeedString := os.Getenv("MOTH_SEED")
-	
-	jsenc := json.NewEncoder(os.Stdout)
-	jsenc.SetEscapeHTML(false)
-	jsenc.SetIndent("", "  ")
-
-	for _, categoryPath := range flag.Args() {
-		categoryName := filepath.Base(categoryPath)
-		categorySeed := seedJoin(baseSeedString, categoryName)
-
-		if *points > 0 {
-			puzzleDir := strconv.Itoa(*points)
-			puzzleSeed := seedJoin(categorySeed, puzzleDir)
-			puzzlePath := filepath.Join(categoryPath, puzzleDir)
-			puzzle, err := ParsePuzzle(puzzlePath, puzzleSeed)
-			if err != nil {
-				log.Print(err)
-				continue
-			}
-			
-			if err := jsenc.Encode(puzzle); err != nil {
-				log.Fatal(err)
-			}
-		} else {
-			puzzles, err := ParseCategory(categoryPath, categorySeed)
-			if err != nil {
-				log.Print(err)
-				continue
-			}
-			
-			if err := jsenc.Encode(puzzles); err != nil {
-				log.Print(err)
-				continue
-			}
-		}
+	t := &T{
+		w: os.Stdout,
+	}
+	action := t.ParseArgs()
+	if err := t.Handle(action); err != nil {
+		log.Fatal(err)
 	}
 }
diff --git a/cmd/transpile/main_test.go b/cmd/transpile/main_test.go
new file mode 100644
index 0000000..352029b
--- /dev/null
+++ b/cmd/transpile/main_test.go
@@ -0,0 +1,88 @@
+package main
+
+import (
+	"bytes"
+	"encoding/json"
+	"testing"
+
+	"github.com/spf13/afero"
+)
+
+var testMothYaml = []byte(`---
+answers:
+  - YAML answer
+pre:
+  authors:
+    - Arthur
+    - Buster
+    - DW
+---
+YAML body
+`)
+var testMothRfc822 = []byte(`author: test
+Author: Arthur
+author: Fred Flintstone
+answer: RFC822 answer
+
+RFC822 body
+`)
+
+func newTestFs() afero.Fs {
+	fs := afero.NewMemMapFs()
+	afero.WriteFile(fs, "cat0/1/puzzle.moth", testMothYaml, 0644)
+	afero.WriteFile(fs, "cat0/1/moo.txt", []byte("Moo."), 0644)
+	afero.WriteFile(fs, "cat0/2/puzzle.moth", testMothRfc822, 0644)
+	afero.WriteFile(fs, "cat0/3/puzzle.moth", testMothYaml, 0644)
+	afero.WriteFile(fs, "cat0/4/puzzle.moth", testMothYaml, 0644)
+	afero.WriteFile(fs, "cat0/5/puzzle.moth", testMothYaml, 0644)
+	afero.WriteFile(fs, "cat0/10/puzzle.moth", []byte(`---
+Answers:
+  - moo
+Authors:
+  - bad field
+---
+body
+`), 0644)
+	afero.WriteFile(fs, "cat0/20/puzzle.moth", []byte("Answer: no\nBadField: yes\n\nbody\n"), 0644)
+	afero.WriteFile(fs, "cat1/93/puzzle.moth", []byte("Answer: no\n\nbody"), 0644)
+	return fs
+}
+
+func TestThings(t *testing.T) {
+	stdout := new(bytes.Buffer)
+	tp := T{
+		w:  stdout,
+		Fs: newTestFs(),
+	}
+
+	if err := tp.Handle("inventory"); err != nil {
+		t.Error(err)
+	}
+	if stdout.String() != "cat0 1 2 3 4 5 10 20\ncat1 93\n" {
+		t.Errorf("Bad inventory: %#v", stdout.String())
+	}
+
+	stdout.Reset()
+	tp.Cat = "cat0"
+	tp.Points = 1
+	if err := tp.Handle("open"); err != nil {
+		t.Error(err)
+	}
+
+	p := Puzzle{}
+	if err := json.Unmarshal(stdout.Bytes(), &p); err != nil {
+		t.Error(err)
+	}
+	if p.Answers[0] != "YAML answer" {
+		t.Error("Didn't return the right object")
+	}
+
+	stdout.Reset()
+	tp.Filename = "moo.txt"
+	if err := tp.Handle("open"); err != nil {
+		t.Error(err)
+	}
+	if stdout.String() != "Moo." {
+		t.Error("Wrong file pulled")
+	}
+}
diff --git a/cmd/transpile/puzzle.go b/cmd/transpile/puzzle.go
index d250869..41b1c60 100644
--- a/cmd/transpile/puzzle.go
+++ b/cmd/transpile/puzzle.go
@@ -3,22 +3,36 @@ package main
 import (
 	"bufio"
 	"bytes"
+	"context"
+	"encoding/json"
 	"fmt"
 	"io"
-	"log"
 	"net/mail"
+	"os/exec"
+	"strconv"
 	"strings"
+	"time"
 
 	"github.com/russross/blackfriday"
+	"github.com/spf13/afero"
 	"gopkg.in/yaml.v2"
 )
 
-type Attachment struct {
-	Filename       string // Filename presented as part of puzzle
-	FilesystemPath string // Filename in backing FS (URL, mothball, or local FS)
-	Listed         bool   // Whether this file is listed as an attachment
+// NewPuzzle returns a new Puzzle for points.
+func NewPuzzle(fs afero.Fs, points int) (*Puzzle, error) {
+	p := &Puzzle{
+		fs: afero.NewBasePathFs(fs, strconv.Itoa(points)),
+	}
+
+	if err := p.parseMoth(); err != nil {
+		return p, err
+	}
+	// BUG(neale): Doesn't yet handle "puzzle.py" or "mkpuzzle"
+
+	return p, nil
 }
 
+// Puzzle contains everything about a puzzle.
 type Puzzle struct {
 	Pre struct {
 		Authors       []string
@@ -42,21 +56,17 @@ type Puzzle struct {
 		Summary string
 	}
 	Answers []string
+	fs      afero.Fs
 }
 
-type HeaderParser func([]byte) (*Puzzle, error)
-
-func YamlParser(input []byte) (*Puzzle, error) {
-	puzzle := new(Puzzle)
-
-	err := yaml.Unmarshal(input, puzzle)
-	if err != nil {
-		return nil, err
-	}
-	return puzzle, nil
+// Attachment carries information about an attached file.
+type Attachment struct {
+	Filename       string // Filename presented as part of puzzle
+	FilesystemPath string // Filename in backing FS (URL, mothball, or local FS)
+	Listed         bool   // Whether this file is listed as an attachment
 }
 
-func AttachmentParser(val []string) []Attachment {
+func legacyAttachmentParser(val []string) []Attachment {
 	ret := make([]Attachment, len(val))
 	for idx, txt := range val {
 		parts := strings.SplitN(txt, " ", 3)
@@ -77,62 +87,70 @@ func AttachmentParser(val []string) []Attachment {
 	return ret
 }
 
-func Rfc822Parser(input []byte) (*Puzzle, error) {
-	msgBytes := append(input, '\n')
-	r := bytes.NewReader(msgBytes)
+func (p *Puzzle) yamlHeaderParser(r io.Reader) error {
+	decoder := yaml.NewDecoder(r)
+	decoder.SetStrict(true)
+	return decoder.Decode(p)
+}
+
+func (p *Puzzle) rfc822HeaderParser(r io.Reader) error {
 	m, err := mail.ReadMessage(r)
 	if err != nil {
-		return nil, err
+		return fmt.Errorf("Parsing RFC822 headers: %v", err)
 	}
 
-	puzzle := new(Puzzle)
 	for key, val := range m.Header {
 		key = strings.ToLower(key)
 		switch key {
 		case "author":
-			puzzle.Pre.Authors = val
+			p.Pre.Authors = val
 		case "pattern":
-			puzzle.Pre.AnswerPattern = val[0]
+			p.Pre.AnswerPattern = val[0]
 		case "script":
-			puzzle.Pre.Scripts = AttachmentParser(val)
+			p.Pre.Scripts = legacyAttachmentParser(val)
 		case "file":
-			puzzle.Pre.Attachments = AttachmentParser(val)
+			p.Pre.Attachments = legacyAttachmentParser(val)
 		case "answer":
-			puzzle.Answers = val
+			p.Answers = val
 		case "summary":
-			puzzle.Debug.Summary = val[0]
+			p.Debug.Summary = val[0]
 		case "hint":
-			puzzle.Debug.Hints = val
+			p.Debug.Hints = val
 		case "ksa":
-			puzzle.Post.KSAs = val
+			p.Post.KSAs = val
 		default:
-			return nil, fmt.Errorf("Unknown header field: %s", key)
+			return fmt.Errorf("Unknown header field: %s", key)
 		}
 	}
 
-	return puzzle, nil
+	return nil
 }
 
-func ParseMoth(r io.Reader) (*Puzzle, error) {
-	headerEnd := ""
+func (p *Puzzle) parseMoth() error {
+	r, err := p.fs.Open("puzzle.moth")
+	if err != nil {
+		return err
+	}
+	defer r.Close()
+
 	headerBuf := new(bytes.Buffer)
-	headerParser := Rfc822Parser
+	headerParser := p.rfc822HeaderParser
+	headerEnd := ""
 
 	scanner := bufio.NewScanner(r)
 	lineNo := 0
 	for scanner.Scan() {
 		line := scanner.Text()
-		lineNo += 1
+		lineNo++
 		if lineNo == 1 {
 			if line == "---" {
-				headerParser = YamlParser
+				headerParser = p.yamlHeaderParser
 				headerEnd = "---"
 				continue
-			} else {
-				headerParser = Rfc822Parser
 			}
 		}
 		if line == headerEnd {
+			headerBuf.WriteRune('\n')
 			break
 		}
 		headerBuf.WriteString(line)
@@ -142,22 +160,55 @@ func ParseMoth(r io.Reader) (*Puzzle, error) {
 	bodyBuf := new(bytes.Buffer)
 	for scanner.Scan() {
 		line := scanner.Text()
-		lineNo += 1
+		lineNo++
 		bodyBuf.WriteString(line)
 		bodyBuf.WriteRune('\n')
 	}
 
-	puzzle, err := headerParser(headerBuf.Bytes())
-	if err != nil {
-		return nil, err
+	if err := headerParser(headerBuf); err != nil {
+		return err
 	}
 
 	// Markdownify the body
-	bodyB := blackfriday.Run(bodyBuf.Bytes())
-	if (puzzle.Pre.Body != "") && (len(bodyB) > 0) {
-		log.Print("Body specified in header; overwriting...")
+	if (p.Pre.Body != "") && (bodyBuf.Len() > 0) {
+		return fmt.Errorf("Puzzle body present in header and in moth body")
 	}
-	puzzle.Pre.Body = string(bodyB)
+	p.Pre.Body = string(blackfriday.Run(bodyBuf.Bytes()))
 
-	return puzzle, nil
+	return nil
+}
+
+func (p *Puzzle) mkpuzzle() error {
+	bfs, ok := p.fs.(*afero.BasePathFs)
+	if !ok {
+		return fmt.Errorf("Fs won't resolve real paths for %v", p)
+	}
+	mkpuzzlePath, err := bfs.RealPath("mkpuzzle")
+	if err != nil {
+		return err
+	}
+
+	ctx, cancel := context.WithTimeout(context.Background(), 2*time.Second)
+	defer cancel()
+
+	cmd := exec.CommandContext(ctx, mkpuzzlePath)
+	stdout, err := cmd.Output()
+	if err != nil {
+		return err
+	}
+
+	jsdec := json.NewDecoder(bytes.NewReader(stdout))
+	jsdec.DisallowUnknownFields()
+	puzzle := new(Puzzle)
+	if err := jsdec.Decode(puzzle); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+// Open returns a newly-opened file.
+func (p *Puzzle) Open(name string) (io.ReadCloser, error) {
+	// BUG(neale): You cannot open generated files in puzzles, only files actually on the disk
+	return p.fs.Open(name)
 }
diff --git a/cmd/transpile/puzzle_test.go b/cmd/transpile/puzzle_test.go
new file mode 100644
index 0000000..4ef8191
--- /dev/null
+++ b/cmd/transpile/puzzle_test.go
@@ -0,0 +1,45 @@
+package main
+
+import (
+	"testing"
+
+	"github.com/spf13/afero"
+)
+
+func TestPuzzle(t *testing.T) {
+	puzzleFs := newTestFs()
+	catFs := afero.NewBasePathFs(puzzleFs, "cat0")
+
+	p1, err := NewPuzzle(catFs, 1)
+	if err != nil {
+		t.Error(err)
+	}
+	t.Log(p1)
+	if (len(p1.Answers) == 0) || (p1.Answers[0] != "YAML answer") {
+		t.Error("Answers are wrong", p1.Answers)
+	}
+	if (len(p1.Pre.Authors) != 3) || (p1.Pre.Authors[1] != "Buster") {
+		t.Error("Authors are wrong", p1.Pre.Authors)
+	}
+	if p1.Pre.Body != "<p>YAML body</p>\n" {
+		t.Errorf("Body parsed wrong: %#v", p1.Pre.Body)
+	}
+
+	p2, err := NewPuzzle(catFs, 2)
+	if err != nil {
+		t.Error(err)
+	}
+	if (len(p2.Answers) == 0) || (p2.Answers[0] != "RFC822 answer") {
+		t.Error("Answers are wrong", p2.Answers)
+	}
+	if (len(p2.Pre.Authors) != 3) || (p2.Pre.Authors[1] != "Arthur") {
+		t.Error("Authors are wrong", p2.Pre.Authors)
+	}
+	if p2.Pre.Body != "<p>RFC822 body</p>\n" {
+		t.Errorf("Body parsed wrong: %#v", p2.Pre.Body)
+	}
+
+	if _, err := NewPuzzle(catFs, 10); err == nil {
+		t.Error("Broken YAML didn't trigger an error")
+	}
+}