blob: 13436387e91322c71a11fc0007e7d768deba9140 [file] [log] [blame]
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Script-driven tests.
// See testdata/script/README for an overview.
package Main_test
import (
"bytes"
"fmt"
"internal/testenv"
"io/ioutil"
"os"
"os/exec"
"path/filepath"
"regexp"
"runtime"
"strconv"
"strings"
"testing"
"time"
"cmd/go/internal/imports"
"cmd/go/internal/par"
"cmd/go/internal/txtar"
)
// TestScript runs the tests in testdata/script/*.txt.
func TestScript(t *testing.T) {
testenv.MustHaveGoBuild(t)
if skipExternal {
t.Skipf("skipping external tests on %s/%s", runtime.GOOS, runtime.GOARCH)
}
files, err := filepath.Glob("testdata/script/*.txt")
if err != nil {
t.Fatal(err)
}
for _, file := range files {
file := file
name := strings.TrimSuffix(filepath.Base(file), ".txt")
t.Run(name, func(t *testing.T) {
t.Parallel()
ts := &testScript{t: t, name: name, file: file}
ts.setup()
if !*testWork {
defer removeAll(ts.workdir)
}
ts.run()
})
}
}
// A testScript holds execution state for a single test script.
type testScript struct {
t *testing.T
workdir string // temporary work dir ($WORK)
log bytes.Buffer // test execution log (printed at end of test)
mark int // offset of next log truncation
cd string // current directory during test execution; initially $WORK/gopath/src
name string // short name of test ("foo")
file string // full file name ("testdata/script/foo.txt")
lineno int // line number currently executing
line string // line currently executing
env []string // environment list (for os/exec)
envMap map[string]string // environment mapping (matches env)
stdout string // standard output from last 'go' command; for 'stdout' command
stderr string // standard error from last 'go' command; for 'stderr' command
stopped bool // test wants to stop early
start time.Time // time phase started
}
var extraEnvKeys = []string{
"SYSTEMROOT", // must be preserved on Windows to find DLLs; golang.org/issue/25210
}
// setup sets up the test execution temporary directory and environment.
func (ts *testScript) setup() {
StartProxy()
ts.workdir = filepath.Join(testTmpDir, "script-"+ts.name)
ts.check(os.MkdirAll(filepath.Join(ts.workdir, "tmp"), 0777))
ts.check(os.MkdirAll(filepath.Join(ts.workdir, "gopath/src"), 0777))
ts.cd = filepath.Join(ts.workdir, "gopath/src")
ts.env = []string{
"WORK=" + ts.workdir, // must be first for ts.abbrev
"PATH=" + os.Getenv("PATH"),
homeEnvName() + "=/no-home",
"GOARCH=" + runtime.GOARCH,
"GOCACHE=" + testGOCACHE,
"GOOS=" + runtime.GOOS,
"GOPATH=" + filepath.Join(ts.workdir, "gopath"),
"GOPROXY=" + proxyURL,
"GOROOT=" + testGOROOT,
tempEnvName() + "=" + filepath.Join(ts.workdir, "tmp"),
"devnull=" + os.DevNull,
}
if runtime.GOOS == "windows" {
ts.env = append(ts.env, "exe=.exe")
} else {
ts.env = append(ts.env, "exe=")
}
for _, key := range extraEnvKeys {
if val := os.Getenv(key); val != "" {
ts.env = append(ts.env, key+"="+val)
}
}
ts.envMap = make(map[string]string)
for _, kv := range ts.env {
if i := strings.Index(kv, "="); i >= 0 {
ts.envMap[kv[:i]] = kv[i+1:]
}
}
}
var execCache par.Cache
// run runs the test script.
func (ts *testScript) run() {
// Truncate log at end of last phase marker,
// discarding details of successful phase.
rewind := func() {
if !testing.Verbose() {
ts.log.Truncate(ts.mark)
}
}
// Insert elapsed time for phase at end of phase marker
markTime := func() {
if ts.mark > 0 && !ts.start.IsZero() {
afterMark := append([]byte{}, ts.log.Bytes()[ts.mark:]...)
ts.log.Truncate(ts.mark - 1) // cut \n and afterMark
fmt.Fprintf(&ts.log, " (%.3fs)\n", time.Since(ts.start).Seconds())
ts.log.Write(afterMark)
}
ts.start = time.Time{}
}
defer func() {
markTime()
// Flush testScript log to testing.T log.
ts.t.Log("\n" + ts.abbrev(ts.log.String()))
}()
// Unpack archive.
a, err := txtar.ParseFile(ts.file)
ts.check(err)
for _, f := range a.Files {
name := ts.mkabs(ts.expand(f.Name))
ts.check(os.MkdirAll(filepath.Dir(name), 0777))
ts.check(ioutil.WriteFile(name, f.Data, 0666))
}
// With -v or -testwork, start log with full environment.
if *testWork || testing.Verbose() {
// Display environment.
ts.cmdEnv(false, nil)
fmt.Fprintf(&ts.log, "\n")
ts.mark = ts.log.Len()
}
// Run script.
// See testdata/script/README for documentation of script form.
script := string(a.Comment)
Script:
for script != "" {
// Extract next line.
ts.lineno++
var line string
if i := strings.Index(script, "\n"); i >= 0 {
line, script = script[:i], script[i+1:]
} else {
line, script = script, ""
}
// # is a comment indicating the start of new phase.
if strings.HasPrefix(line, "#") {
// If there was a previous phase, it succeeded,
// so rewind the log to delete its details (unless -v is in use).
// If nothing has happened at all since the mark,
// rewinding is a no-op and adding elapsed time
// for doing nothing is meaningless, so don't.
if ts.log.Len() > ts.mark {
rewind()
markTime()
}
// Print phase heading and mark start of phase output.
fmt.Fprintf(&ts.log, "%s\n", line)
ts.mark = ts.log.Len()
ts.start = time.Now()
continue
}
// Parse input line. Ignore blanks entirely.
args := ts.parse(line)
if len(args) == 0 {
continue
}
// Echo command to log.
fmt.Fprintf(&ts.log, "> %s\n", line)
// Command prefix [cond] means only run this command if cond is satisfied.
for strings.HasPrefix(args[0], "[") && strings.HasSuffix(args[0], "]") {
cond := args[0]
cond = cond[1 : len(cond)-1]
cond = strings.TrimSpace(cond)
args = args[1:]
if len(args) == 0 {
ts.fatalf("missing command after condition")
}
want := true
if strings.HasPrefix(cond, "!") {
want = false
cond = strings.TrimSpace(cond[1:])
}
// Known conds are: $GOOS, $GOARCH, runtime.Compiler, and 'short' (for testing.Short).
//
// NOTE: If you make changes here, update testdata/script/README too!
//
ok := false
switch cond {
case runtime.GOOS, runtime.GOARCH, runtime.Compiler:
ok = true
case "short":
ok = testing.Short()
case "cgo":
ok = canCgo
case "msan":
ok = canMSan
case "race":
ok = canRace
case "net":
ok = testenv.HasExternalNetwork()
case "link":
ok = testenv.HasLink()
case "symlink":
ok = testenv.HasSymlink()
default:
if strings.HasPrefix(cond, "exec:") {
prog := cond[len("exec:"):]
ok = execCache.Do(prog, func() interface{} {
_, err := exec.LookPath(prog)
return err == nil
}).(bool)
break
}
if !imports.KnownArch[cond] && !imports.KnownOS[cond] && cond != "gc" && cond != "gccgo" {
ts.fatalf("unknown condition %q", cond)
}
}
if ok != want {
// Don't run rest of line.
continue Script
}
}
// Command prefix ! means negate the expectations about this command:
// go command should fail, match should not be found, etc.
neg := false
if args[0] == "!" {
neg = true
args = args[1:]
if len(args) == 0 {
ts.fatalf("! on line by itself")
}
}
// Run command.
cmd := scriptCmds[args[0]]
if cmd == nil {
ts.fatalf("unknown command %q", args[0])
}
cmd(ts, neg, args[1:])
// Command can ask script to stop early.
if ts.stopped {
return
}
}
// Final phase ended.
rewind()
markTime()
fmt.Fprintf(&ts.log, "PASS\n")
}
// scriptCmds are the script command implementations.
// Keep list and the implementations below sorted by name.
//
// NOTE: If you make changes here, update testdata/script/README too!
//
var scriptCmds = map[string]func(*testScript, bool, []string){
"addcrlf": (*testScript).cmdAddcrlf,
"cd": (*testScript).cmdCd,
"cmp": (*testScript).cmdCmp,
"cp": (*testScript).cmdCp,
"env": (*testScript).cmdEnv,
"exec": (*testScript).cmdExec,
"exists": (*testScript).cmdExists,
"go": (*testScript).cmdGo,
"grep": (*testScript).cmdGrep,
"mkdir": (*testScript).cmdMkdir,
"rm": (*testScript).cmdRm,
"skip": (*testScript).cmdSkip,
"stale": (*testScript).cmdStale,
"stderr": (*testScript).cmdStderr,
"stdout": (*testScript).cmdStdout,
"stop": (*testScript).cmdStop,
"symlink": (*testScript).cmdSymlink,
}
// addcrlf adds CRLF line endings to the named files.
func (ts *testScript) cmdAddcrlf(neg bool, args []string) {
if len(args) == 0 {
ts.fatalf("usage: addcrlf file...")
}
for _, file := range args {
file = ts.mkabs(file)
data, err := ioutil.ReadFile(file)
ts.check(err)
ts.check(ioutil.WriteFile(file, bytes.Replace(data, []byte("\n"), []byte("\r\n"), -1), 0666))
}
}
// cd changes to a different directory.
func (ts *testScript) cmdCd(neg bool, args []string) {
if neg {
ts.fatalf("unsupported: ! cd")
}
if len(args) != 1 {
ts.fatalf("usage: cd dir")
}
dir := args[0]
if !filepath.IsAbs(dir) {
dir = filepath.Join(ts.cd, dir)
}
info, err := os.Stat(dir)
if os.IsNotExist(err) {
ts.fatalf("directory %s does not exist", dir)
}
ts.check(err)
if !info.IsDir() {
ts.fatalf("%s is not a directory", dir)
}
ts.cd = dir
fmt.Fprintf(&ts.log, "%s\n", ts.cd)
}
// cmp compares two files.
func (ts *testScript) cmdCmp(neg bool, args []string) {
if neg {
// It would be strange to say "this file can have any content except this precise byte sequence".
ts.fatalf("unsupported: ! cmp")
}
if len(args) != 2 {
ts.fatalf("usage: cmp file1 file2")
}
name1, name2 := args[0], args[1]
var text1, text2 string
if name1 == "stdout" {
text1 = ts.stdout
} else if name1 == "stderr" {
text1 = ts.stderr
} else {
data, err := ioutil.ReadFile(ts.mkabs(name1))
ts.check(err)
text1 = string(data)
}
data, err := ioutil.ReadFile(ts.mkabs(name2))
ts.check(err)
text2 = string(data)
if text1 == text2 {
return
}
fmt.Fprintf(&ts.log, "[diff -%s +%s]\n%s\n", name1, name2, diff(text1, text2))
ts.fatalf("%s and %s differ", name1, name2)
}
// cp copies files, maybe eventually directories.
func (ts *testScript) cmdCp(neg bool, args []string) {
if neg {
ts.fatalf("unsupported: ! cp")
}
if len(args) < 2 {
ts.fatalf("usage: cp src... dst")
}
dst := ts.mkabs(args[len(args)-1])
info, err := os.Stat(dst)
dstDir := err == nil && info.IsDir()
if len(args) > 2 && !dstDir {
ts.fatalf("cp: destination %s is not a directory", dst)
}
for _, arg := range args[:len(args)-1] {
src := ts.mkabs(arg)
info, err := os.Stat(src)
ts.check(err)
data, err := ioutil.ReadFile(src)
ts.check(err)
targ := dst
if dstDir {
targ = filepath.Join(dst, filepath.Base(src))
}
ts.check(ioutil.WriteFile(targ, data, info.Mode()&0777))
}
}
// env displays or adds to the environment.
func (ts *testScript) cmdEnv(neg bool, args []string) {
if neg {
ts.fatalf("unsupported: ! env")
}
if len(args) == 0 {
printed := make(map[string]bool) // env list can have duplicates; only print effective value (from envMap) once
for _, kv := range ts.env {
k := kv[:strings.Index(kv, "=")]
if !printed[k] {
fmt.Fprintf(&ts.log, "%s=%s\n", k, ts.envMap[k])
}
}
return
}
for _, env := range args {
i := strings.Index(env, "=")
if i < 0 {
// Display value instead of setting it.
fmt.Fprintf(&ts.log, "%s=%s\n", env, ts.envMap[env])
continue
}
ts.env = append(ts.env, env)
ts.envMap[env[:i]] = env[i+1:]
}
}
// exec runs the given command.
func (ts *testScript) cmdExec(neg bool, args []string) {
if len(args) < 1 {
ts.fatalf("usage: exec program [args...]")
}
var err error
ts.stdout, ts.stderr, err = ts.exec(args[0], args[1:]...)
if ts.stdout != "" {
fmt.Fprintf(&ts.log, "[stdout]\n%s", ts.stdout)
}
if ts.stderr != "" {
fmt.Fprintf(&ts.log, "[stderr]\n%s", ts.stderr)
}
if err != nil {
fmt.Fprintf(&ts.log, "[%v]\n", err)
if !neg {
ts.fatalf("unexpected command failure")
}
} else {
if neg {
ts.fatalf("unexpected command success")
}
}
}
// exists checks that the list of files exists.
func (ts *testScript) cmdExists(neg bool, args []string) {
var readonly bool
if len(args) > 0 && args[0] == "-readonly" {
readonly = true
args = args[1:]
}
if len(args) == 0 {
ts.fatalf("usage: exists [-readonly] file...")
}
for _, file := range args {
file = ts.mkabs(file)
info, err := os.Stat(file)
if err == nil && neg {
what := "file"
if info.IsDir() {
what = "directory"
}
ts.fatalf("%s %s unexpectedly exists", what, file)
}
if err != nil && !neg {
ts.fatalf("%s does not exist", file)
}
if err == nil && !neg && readonly && info.Mode()&0222 != 0 {
ts.fatalf("%s exists but is writable", file)
}
}
}
// go runs the go command.
func (ts *testScript) cmdGo(neg bool, args []string) {
ts.cmdExec(neg, append([]string{testGo}, args...))
}
// mkdir creates directories.
func (ts *testScript) cmdMkdir(neg bool, args []string) {
if neg {
ts.fatalf("unsupported: ! mkdir")
}
if len(args) < 1 {
ts.fatalf("usage: mkdir dir...")
}
for _, arg := range args {
ts.check(os.MkdirAll(ts.mkabs(arg), 0777))
}
}
// rm removes files or directories.
func (ts *testScript) cmdRm(neg bool, args []string) {
if neg {
ts.fatalf("unsupported: ! rm")
}
if len(args) < 1 {
ts.fatalf("usage: rm file...")
}
for _, arg := range args {
file := ts.mkabs(arg)
removeAll(file) // does chmod and then attempts rm
ts.check(os.RemoveAll(file)) // report error
}
}
// skip marks the test skipped.
func (ts *testScript) cmdSkip(neg bool, args []string) {
if len(args) > 1 {
ts.fatalf("usage: skip [msg]")
}
if neg {
ts.fatalf("unsupported: ! skip")
}
if len(args) == 1 {
ts.t.Skip(args[0])
}
ts.t.Skip()
}
// stale checks that the named build targets are stale.
func (ts *testScript) cmdStale(neg bool, args []string) {
if len(args) == 0 {
ts.fatalf("usage: stale target...")
}
tmpl := "{{if .Error}}{{.ImportPath}}: {{.Error.Err}}{else}}"
if neg {
tmpl += "{{if .Stale}}{{.ImportPath}} is unexpectedly stale{{end}}"
} else {
tmpl += "{{if not .Stale}}{{.ImportPath}} is unexpectedly NOT stale{{end}}"
}
tmpl += "{{end}}"
goArgs := append([]string{"list", "-e", "-f=" + tmpl}, args...)
stdout, stderr, err := ts.exec(testGo, goArgs...)
if err != nil {
ts.fatalf("go list: %v\n%s%s", err, stdout, stderr)
}
if stdout != "" {
ts.fatalf("%s", stdout)
}
}
// stdout checks that the last go command standard output matches a regexp.
func (ts *testScript) cmdStdout(neg bool, args []string) {
scriptMatch(ts, neg, args, ts.stdout, "stdout")
}
// stderr checks that the last go command standard output matches a regexp.
func (ts *testScript) cmdStderr(neg bool, args []string) {
scriptMatch(ts, neg, args, ts.stderr, "stderr")
}
// grep checks that file content matches a regexp.
// Like stdout/stderr and unlike Unix grep, it accepts Go regexp syntax.
func (ts *testScript) cmdGrep(neg bool, args []string) {
scriptMatch(ts, neg, args, "", "grep")
}
// scriptMatch implements both stdout and stderr.
func scriptMatch(ts *testScript, neg bool, args []string, text, name string) {
n := 0
if len(args) >= 1 && strings.HasPrefix(args[0], "-count=") {
if neg {
ts.fatalf("cannot use -count= with negated match")
}
var err error
n, err = strconv.Atoi(args[0][len("-count="):])
if err != nil {
ts.fatalf("bad -count=: %v", err)
}
if n < 1 {
ts.fatalf("bad -count=: must be at least 1")
}
args = args[1:]
}
extraUsage := ""
want := 1
if name == "grep" {
extraUsage = " file"
want = 2
}
if len(args) != want {
ts.fatalf("usage: %s [-count=N] 'pattern' file%s", name, extraUsage)
}
pattern := args[0]
re, err := regexp.Compile(`(?m)` + pattern)
ts.check(err)
isGrep := name == "grep"
if isGrep {
name = args[1] // for error messages
data, err := ioutil.ReadFile(ts.mkabs(args[1]))
ts.check(err)
text = string(data)
}
if neg {
if re.MatchString(text) {
if isGrep {
fmt.Fprintf(&ts.log, "[%s]\n%s\n", name, text)
}
ts.fatalf("unexpected match for %#q found in %s: %s", pattern, name, re.FindString(text))
}
} else {
if !re.MatchString(text) {
if isGrep {
fmt.Fprintf(&ts.log, "[%s]\n%s\n", name, text)
}
ts.fatalf("no match for %#q found in %s", pattern, name)
}
if n > 0 {
count := len(re.FindAllString(text, -1))
if count != n {
if isGrep {
fmt.Fprintf(&ts.log, "[%s]\n%s\n", name, text)
}
ts.fatalf("have %d matches for %#q, want %d", count, pattern, n)
}
}
}
}
// stop stops execution of the test (marking it passed).
func (ts *testScript) cmdStop(neg bool, args []string) {
if neg {
ts.fatalf("unsupported: ! stop")
}
if len(args) > 1 {
ts.fatalf("usage: stop [msg]")
}
if len(args) == 1 {
fmt.Fprintf(&ts.log, "stop: %s\n", args[0])
} else {
fmt.Fprintf(&ts.log, "stop\n")
}
ts.stopped = true
}
// symlink creates a symbolic link.
func (ts *testScript) cmdSymlink(neg bool, args []string) {
if neg {
ts.fatalf("unsupported: ! symlink")
}
if len(args) != 3 || args[1] != "->" {
ts.fatalf("usage: symlink file -> target")
}
// Note that the link target args[2] is not interpreted with mkabs:
// it will be interpreted relative to the directory file is in.
ts.check(os.Symlink(args[2], ts.mkabs(args[0])))
}
// Helpers for command implementations.
// abbrev abbreviates the actual work directory in the string s to the literal string "$WORK".
func (ts *testScript) abbrev(s string) string {
s = strings.Replace(s, ts.workdir, "$WORK", -1)
if *testWork {
// Expose actual $WORK value in environment dump on first line of work script,
// so that the user can find out what directory -testwork left behind.
s = "WORK=" + ts.workdir + "\n" + strings.TrimPrefix(s, "WORK=$WORK\n")
}
return s
}
// check calls ts.fatalf if err != nil.
func (ts *testScript) check(err error) {
if err != nil {
ts.fatalf("%v", err)
}
}
// exec runs the given command line (an actual subprocess, not simulated)
// in ts.cd with environment ts.env and then returns collected standard output and standard error.
func (ts *testScript) exec(command string, args ...string) (stdout, stderr string, err error) {
cmd := exec.Command(testGo, args...)
cmd.Dir = ts.cd
cmd.Env = append(ts.env, "PWD="+ts.cd)
var stdoutBuf, stderrBuf strings.Builder
cmd.Stdout = &stdoutBuf
cmd.Stderr = &stderrBuf
err = cmd.Run()
return stdoutBuf.String(), stderrBuf.String(), err
}
// expand applies environment variable expansion to the string s.
func (ts *testScript) expand(s string) string {
return os.Expand(s, func(key string) string { return ts.envMap[key] })
}
// fatalf aborts the test with the given failure message.
func (ts *testScript) fatalf(format string, args ...interface{}) {
fmt.Fprintf(&ts.log, "FAIL: %s:%d: %s\n", ts.file, ts.lineno, fmt.Sprintf(format, args...))
ts.t.FailNow()
}
// mkabs interprets file relative to the test script's current directory
// and returns the corresponding absolute path.
func (ts *testScript) mkabs(file string) string {
if filepath.IsAbs(file) {
return file
}
return filepath.Join(ts.cd, file)
}
// parse parses a single line as a list of space-separated arguments
// subject to environment variable expansion (but not resplitting).
// Single quotes around text disable splitting and expansion.
// To embed a single quote, double it: 'Don''t communicate by sharing memory.'
func (ts *testScript) parse(line string) []string {
ts.line = line
var (
args []string
arg string // text of current arg so far (need to add line[start:i])
start = -1 // if >= 0, position where current arg text chunk starts
quoted = false // currently processing quoted text
)
for i := 0; ; i++ {
if !quoted && (i >= len(line) || line[i] == ' ' || line[i] == '\t' || line[i] == '\r' || line[i] == '#') {
// Found arg-separating space.
if start >= 0 {
arg += ts.expand(line[start:i])
args = append(args, arg)
start = -1
arg = ""
}
if i >= len(line) || line[i] == '#' {
break
}
continue
}
if i >= len(line) {
ts.fatalf("unterminated quoted argument")
}
if line[i] == '\'' {
if !quoted {
// starting a quoted chunk
if start >= 0 {
arg += ts.expand(line[start:i])
}
start = i + 1
quoted = true
continue
}
// 'foo''bar' means foo'bar, like in rc shell and Pascal.
if i+1 < len(line) && line[i+1] == '\'' {
arg += line[start:i]
start = i + 1
i++ // skip over second ' before next iteration
continue
}
// ending a quoted chunk
arg += line[start:i]
start = i + 1
quoted = false
continue
}
// found character worth saving; make sure we're saving
if start < 0 {
start = i
}
}
return args
}
// diff returns a formatted diff of the two texts,
// showing the entire text and the minimum line-level
// additions and removals to turn text1 into text2.
// (That is, lines only in text1 appear with a leading -,
// and lines only in text2 appear with a leading +.)
func diff(text1, text2 string) string {
if text1 != "" && !strings.HasSuffix(text1, "\n") {
text1 += "(missing final newline)"
}
lines1 := strings.Split(text1, "\n")
lines1 = lines1[:len(lines1)-1] // remove empty string after final line
if text2 != "" && !strings.HasSuffix(text2, "\n") {
text2 += "(missing final newline)"
}
lines2 := strings.Split(text2, "\n")
lines2 = lines2[:len(lines2)-1] // remove empty string after final line
// Naive dynamic programming algorithm for edit distance.
// https://en.wikipedia.org/wiki/Wagner–Fischer_algorithm
// dist[i][j] = edit distance between lines1[:len(lines1)-i] and lines2[:len(lines2)-j]
// (The reversed indices make following the minimum cost path
// visit lines in the same order as in the text.)
dist := make([][]int, len(lines1)+1)
for i := range dist {
dist[i] = make([]int, len(lines2)+1)
if i == 0 {
for j := range dist[0] {
dist[0][j] = j
}
continue
}
for j := range dist[i] {
if j == 0 {
dist[i][0] = i
continue
}
cost := dist[i][j-1] + 1
if cost > dist[i-1][j]+1 {
cost = dist[i-1][j] + 1
}
if lines1[len(lines1)-i] == lines2[len(lines2)-j] {
if cost > dist[i-1][j-1] {
cost = dist[i-1][j-1]
}
}
dist[i][j] = cost
}
}
var buf strings.Builder
i, j := len(lines1), len(lines2)
for i > 0 || j > 0 {
cost := dist[i][j]
if i > 0 && j > 0 && cost == dist[i-1][j-1] && lines1[len(lines1)-i] == lines2[len(lines2)-j] {
fmt.Fprintf(&buf, " %s\n", lines1[len(lines1)-i])
i--
j--
} else if i > 0 && cost == dist[i-1][j]+1 {
fmt.Fprintf(&buf, "-%s\n", lines1[len(lines1)-i])
i--
} else {
fmt.Fprintf(&buf, "+%s\n", lines2[len(lines2)-j])
j--
}
}
return buf.String()
}
var diffTests = []struct {
text1 string
text2 string
diff string
}{
{"a b c", "a b d e f", "a b -c +d +e +f"},
{"", "a b c", "+a +b +c"},
{"a b c", "", "-a -b -c"},
{"a b c", "d e f", "-a -b -c +d +e +f"},
{"a b c d e f", "a b d e f", "a b -c d e f"},
{"a b c e f", "a b c d e f", "a b c +d e f"},
}
func TestDiff(t *testing.T) {
for _, tt := range diffTests {
// Turn spaces into \n.
text1 := strings.Replace(tt.text1, " ", "\n", -1)
if text1 != "" {
text1 += "\n"
}
text2 := strings.Replace(tt.text2, " ", "\n", -1)
if text2 != "" {
text2 += "\n"
}
out := diff(text1, text2)
// Cut final \n, cut spaces, turn remaining \n into spaces.
out = strings.Replace(strings.Replace(strings.TrimSuffix(out, "\n"), " ", "", -1), "\n", " ", -1)
if out != tt.diff {
t.Errorf("diff(%q, %q) = %q, want %q", text1, text2, out, tt.diff)
}
}
}