From 85830ee3a9539e66e3192d047aad86eeb1f88a08 Mon Sep 17 00:00:00 2001
From: Tom Payne <twpayne@gmail.com>
Date: Wed, 16 Sep 2020 16:00:20 +0200
Subject: [PATCH] testscript: add unix2dos command

---
 testscript/cmd.go             | 79 ++++++++++++++++++++++++++---------
 testscript/testscript_test.go | 19 +++++++++
 2 files changed, 79 insertions(+), 19 deletions(-)

diff --git a/testscript/cmd.go b/testscript/cmd.go
index b73e6ce7..598ffe30 100644
--- a/testscript/cmd.go
+++ b/testscript/cmd.go
@@ -5,6 +5,8 @@
 package testscript
 
 import (
+	"bufio"
+	"bytes"
 	"fmt"
 	"io/ioutil"
 	"os"
@@ -24,25 +26,26 @@ import (
 // NOTE: If you make changes here, update doc.go.
 //
 var scriptCmds = map[string]func(*TestScript, bool, []string){
-	"cd":      (*TestScript).cmdCd,
-	"chmod":   (*TestScript).cmdChmod,
-	"cmp":     (*TestScript).cmdCmp,
-	"cmpenv":  (*TestScript).cmdCmpenv,
-	"cp":      (*TestScript).cmdCp,
-	"env":     (*TestScript).cmdEnv,
-	"exec":    (*TestScript).cmdExec,
-	"exists":  (*TestScript).cmdExists,
-	"grep":    (*TestScript).cmdGrep,
-	"mkdir":   (*TestScript).cmdMkdir,
-	"rm":      (*TestScript).cmdRm,
-	"unquote": (*TestScript).cmdUnquote,
-	"skip":    (*TestScript).cmdSkip,
-	"stdin":   (*TestScript).cmdStdin,
-	"stderr":  (*TestScript).cmdStderr,
-	"stdout":  (*TestScript).cmdStdout,
-	"stop":    (*TestScript).cmdStop,
-	"symlink": (*TestScript).cmdSymlink,
-	"wait":    (*TestScript).cmdWait,
+	"cd":       (*TestScript).cmdCd,
+	"chmod":    (*TestScript).cmdChmod,
+	"cmp":      (*TestScript).cmdCmp,
+	"cmpenv":   (*TestScript).cmdCmpenv,
+	"cp":       (*TestScript).cmdCp,
+	"env":      (*TestScript).cmdEnv,
+	"exec":     (*TestScript).cmdExec,
+	"exists":   (*TestScript).cmdExists,
+	"grep":     (*TestScript).cmdGrep,
+	"mkdir":    (*TestScript).cmdMkdir,
+	"rm":       (*TestScript).cmdRm,
+	"unquote":  (*TestScript).cmdUnquote,
+	"skip":     (*TestScript).cmdSkip,
+	"stdin":    (*TestScript).cmdStdin,
+	"stderr":   (*TestScript).cmdStderr,
+	"stdout":   (*TestScript).cmdStdout,
+	"stop":     (*TestScript).cmdStop,
+	"symlink":  (*TestScript).cmdSymlink,
+	"unix2dos": (*TestScript).cmdUNIX2DOS,
+	"wait":     (*TestScript).cmdWait,
 }
 
 // cd changes to a different directory.
@@ -409,6 +412,26 @@ func (ts *TestScript) cmdSymlink(neg bool, args []string) {
 	ts.Check(os.Symlink(args[2], ts.MkAbs(args[0])))
 }
 
+// cmdUNIX2DOS converts files from UNIX line endings to DOS line endings.
+func (ts *TestScript) cmdUNIX2DOS(neg bool, args []string) {
+	if neg {
+		ts.Fatalf("unsupported: ! unix2dos")
+	}
+	if len(args) < 1 {
+		ts.Fatalf("usage: unix2dos paths...")
+	}
+	for _, arg := range args {
+		filename := ts.MkAbs(arg)
+		data, err := ioutil.ReadFile(filename)
+		ts.Check(err)
+		dosData, err := unix2DOS(data)
+		ts.Check(err)
+		if err := ioutil.WriteFile(filename, dosData, 0666); err != nil {
+			ts.Fatalf("%s: %v", filename, err)
+		}
+	}
+}
+
 // Tait waits for background commands to exit, setting stderr and stdout to their result.
 func (ts *TestScript) cmdWait(neg bool, args []string) {
 	if neg {
@@ -520,3 +543,21 @@ func scriptMatch(ts *TestScript, neg bool, args []string, text, name string) {
 		}
 	}
 }
+
+// unix2DOS returns data with UNIX line endings converted to DOS line endings.
+func unix2DOS(data []byte) ([]byte, error) {
+	sb := &strings.Builder{}
+	s := bufio.NewScanner(bytes.NewReader(data))
+	for s.Scan() {
+		if _, err := sb.Write(s.Bytes()); err != nil {
+			return nil, err
+		}
+		if _, err := sb.WriteString("\r\n"); err != nil {
+			return nil, err
+		}
+	}
+	if err := s.Err(); err != nil {
+		return nil, err
+	}
+	return []byte(sb.String()), nil
+}
diff --git a/testscript/testscript_test.go b/testscript/testscript_test.go
index d9e50948..a28e3098 100644
--- a/testscript/testscript_test.go
+++ b/testscript/testscript_test.go
@@ -5,6 +5,7 @@
 package testscript
 
 import (
+	"bytes"
 	"errors"
 	"fmt"
 	"io/ioutil"
@@ -307,6 +308,24 @@ func TestBadDir(t *testing.T) {
 	}
 }
 
+func TestUNIX2DOS(t *testing.T) {
+	for data, want := range map[string]string{
+		"":         "",           // Preserve empty files.
+		"\n":       "\r\n",       // Convert LF to CRLF in a file containing a single empty line.
+		"\r\n":     "\r\n",       // Preserve CRLF in a single line file.
+		"a":        "a\r\n",      // Append CRLF to a single line file with no line terminator.
+		"a\n":      "a\r\n",      // Convert LF to CRLF in a file containing a single non-empty line.
+		"a\r\n":    "a\r\n",      // Preserve CRLF in a file containing a single non-empty line.
+		"a\nb\n":   "a\r\nb\r\n", // Convert LF to CRLF in multiline UNIX file.
+		"a\r\nb\n": "a\r\nb\r\n", // Convert LF to CRLF in a file containing a mix of UNIX and DOS lines.
+		"a\nb\r\n": "a\r\nb\r\n", // Convert LF to CRLF in a file containing a mix of UNIX and DOS lines.
+	} {
+		if got, err := unix2DOS([]byte(data)); err != nil || !bytes.Equal(got, []byte(want)) {
+			t.Errorf("unix2DOS(%q) == %q, %v, want %q, nil", data, got, err, want)
+		}
+	}
+}
+
 func setSpecialVal(ts *TestScript, neg bool, args []string) {
 	ts.Setenv("SPECIALVAL", "42")
 }