src/go/build/deps_test.go

   1 // Copyright 2022 The Go Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style
   3 // license that can be found in the LICENSE file.
   4
   5 // This file exercises the import parser but also checks that
   6 // some low-level packages do not have new dependencies added.
   7
   8 package build
   9
  10 import (
  11         "bytes"
  12         "fmt"
  13         "go/token"
  14         "internal/dag"
  15         "internal/testenv"
  16         "io/fs"
  17         "os"
  18         "path/filepath"
  19         "runtime"
  20         "sort"
  21         "strings"
  22         "testing"
  23 )
  24
  25 // depsRules defines the expected dependencies between packages in
  26 // the Go source tree. It is a statement of policy.
  27 //
  28 // DO NOT CHANGE THIS DATA TO FIX BUILDS.
  29 // Existing packages should not have their constraints relaxed
  30 // without prior discussion.
  31 // Negative assertions should almost never be removed.
  32 //
  33 // "a < b" means package b can import package a.
  34 //
  35 // See `go doc internal/dag' for the full syntax.
  36 //
  37 // All-caps names are pseudo-names for specific points
  38 // in the dependency lattice.
  39 var depsRules = `
  40         # No dependencies allowed for any of these packages.
  41         NONE
  42         < constraints, container/list, container/ring,
  43           internal/cfg, internal/coverage, internal/coverage/rtcov,
  44           internal/coverage/uleb128, internal/coverage/calloc,
  45           internal/cpu, internal/goarch, internal/godebugs,
  46           internal/goexperiment, internal/goos,
  47           internal/goversion, internal/nettrace, internal/platform,
  48           log/internal,
  49           unicode/utf8, unicode/utf16, unicode,
  50           unsafe;
  51
  52         # slices depends on unsafe for overlapping check.
  53         unsafe
  54         < slices;
  55
  56         # These packages depend only on internal/goarch and unsafe.
  57         internal/goarch, unsafe
  58         < internal/abi;
  59
  60         unsafe < maps;
  61
  62         # RUNTIME is the core runtime group of packages, all of them very light-weight.
  63         internal/abi, internal/cpu, internal/goarch,
  64         internal/coverage/rtcov, internal/godebugs, internal/goexperiment,
  65         internal/goos, unsafe
  66         < internal/bytealg
  67         < internal/itoa
  68         < internal/unsafeheader
  69         < runtime/internal/sys
  70         < runtime/internal/syscall
  71         < runtime/internal/atomic
  72         < runtime/internal/math
  73         < runtime
  74         < sync/atomic
  75         < internal/race
  76         < sync
  77         < internal/bisect
  78         < internal/godebug
  79         < internal/reflectlite
  80         < errors
  81         < internal/oserror, math/bits
  82         < RUNTIME;
  83
  84         RUNTIME
  85         < sort
  86         < container/heap;
  87
  88         RUNTIME
  89         < io;
  90
  91         RUNTIME
  92         < arena;
  93
  94         syscall !< io;
  95         reflect !< sort;
  96
  97         RUNTIME, unicode/utf8
  98         < path;
  99
 100         unicode !< path;
 101
 102         # SYSCALL is RUNTIME plus the packages necessary for basic system calls.
 103         RUNTIME, unicode/utf8, unicode/utf16
 104         < internal/syscall/windows/sysdll, syscall/js
 105         < syscall
 106         < internal/syscall/unix, internal/syscall/windows, internal/syscall/windows/registry
 107         < internal/syscall/execenv
 108         < SYSCALL;
 109
 110         # TIME is SYSCALL plus the core packages about time, including context.
 111         SYSCALL
 112         < time/tzdata
 113         < time
 114         < context
 115         < TIME;
 116
 117         TIME, io, path, sort
 118         < io/fs;
 119
 120         # MATH is RUNTIME plus the basic math packages.
 121         RUNTIME
 122         < math
 123         < MATH;
 124
 125         unicode !< math;
 126
 127         MATH
 128         < math/cmplx;
 129
 130         MATH
 131         < math/rand;
 132
 133         MATH
 134         < runtime/metrics;
 135
 136         MATH, unicode/utf8
 137         < strconv;
 138
 139         unicode !< strconv;
 140
 141         # STR is basic string and buffer manipulation.
 142         RUNTIME, io, unicode/utf8, unicode/utf16, unicode
 143         < bytes, strings
 144         < bufio;
 145
 146         bufio, path, strconv
 147         < STR;
 148
 149         # OS is basic OS access, including helpers (path/filepath, os/exec, etc).
 150         # OS includes string routines, but those must be layered above package os.
 151         # OS does not include reflection.
 152         io/fs
 153         < internal/testlog
 154         < internal/poll
 155         < internal/safefilepath
 156         < os
 157         < os/signal;
 158
 159         io/fs
 160         < embed;
 161
 162         unicode, fmt !< net, os, os/signal;
 163
 164         os/signal, STR
 165         < path/filepath
 166         < io/ioutil;
 167
 168         path/filepath, internal/godebug < os/exec;
 169
 170         io/ioutil, os/exec, os/signal
 171         < OS;
 172
 173         reflect !< OS;
 174
 175         OS
 176         < golang.org/x/sys/cpu;
 177
 178         # FMT is OS (which includes string routines) plus reflect and fmt.
 179         # It does not include package log, which should be avoided in core packages.
 180         arena, strconv, unicode
 181         < reflect;
 182
 183         os, reflect
 184         < internal/fmtsort
 185         < fmt;
 186
 187         OS, fmt
 188         < FMT;
 189
 190         log !< FMT;
 191
 192         # Misc packages needing only FMT.
 193         FMT
 194         < html,
 195           internal/dag,
 196           internal/goroot,
 197           internal/types/errors,
 198           mime/quotedprintable,
 199           net/internal/socktest,
 200           net/url,
 201           runtime/trace,
 202           text/scanner,
 203           text/tabwriter;
 204
 205         io, reflect
 206         < internal/saferio;
 207
 208         # encodings
 209         # core ones do not use fmt.
 210         io, strconv
 211         < encoding;
 212
 213         encoding, reflect
 214         < encoding/binary
 215         < encoding/base32, encoding/base64;
 216
 217         FMT, encoding < flag;
 218
 219         fmt !< encoding/base32, encoding/base64;
 220
 221         FMT, encoding/base32, encoding/base64, internal/saferio
 222         < encoding/ascii85, encoding/csv, encoding/gob, encoding/hex,
 223           encoding/json, encoding/pem, encoding/xml, mime;
 224
 225         # hashes
 226         io
 227         < hash
 228         < hash/adler32, hash/crc32, hash/crc64, hash/fnv;
 229
 230         # math/big
 231         FMT, encoding/binary, math/rand
 232         < math/big;
 233
 234         # compression
 235         FMT, encoding/binary, hash/adler32, hash/crc32
 236         < compress/bzip2, compress/flate, compress/lzw, internal/zstd
 237         < archive/zip, compress/gzip, compress/zlib;
 238
 239         # templates
 240         FMT
 241         < text/template/parse;
 242
 243         net/url, text/template/parse
 244         < text/template
 245         < internal/lazytemplate;
 246
 247         encoding/json, html, text/template
 248         < html/template;
 249
 250         # regexp
 251         FMT
 252         < regexp/syntax
 253         < regexp
 254         < internal/lazyregexp;
 255
 256         # suffix array
 257         encoding/binary, regexp
 258         < index/suffixarray;
 259
 260         # executable parsing
 261         FMT, encoding/binary, compress/zlib, internal/saferio, internal/zstd
 262         < runtime/debug
 263         < debug/dwarf
 264         < debug/elf, debug/gosym, debug/macho, debug/pe, debug/plan9obj, internal/xcoff
 265         < debug/buildinfo
 266         < DEBUG;
 267
 268         # go parser and friends.
 269         FMT
 270         < go/token
 271         < go/scanner
 272         < go/ast
 273         < go/internal/typeparams;
 274
 275         FMT
 276         < go/build/constraint, go/doc/comment;
 277
 278         go/internal/typeparams, go/build/constraint
 279         < go/parser;
 280
 281         go/doc/comment, go/parser, text/tabwriter
 282         < go/printer
 283         < go/format;
 284
 285         math/big, go/token
 286         < go/constant;
 287
 288         container/heap, go/constant, go/parser, internal/types/errors
 289         < go/types;
 290
 291         # The vast majority of standard library packages should not be resorting to regexp.
 292         # go/types is a good chokepoint. It shouldn't use regexp, nor should anything
 293         # that is low-enough level to be used by go/types.
 294         regexp !< go/types;
 295
 296         go/doc/comment, go/parser, internal/lazyregexp, text/template
 297         < go/doc;
 298
 299         FMT, internal/goexperiment
 300         < internal/buildcfg;
 301
 302         go/build/constraint, go/doc, go/parser, internal/buildcfg, internal/goroot, internal/goversion, internal/platform
 303         < go/build;
 304
 305         # databases
 306         FMT
 307         < database/sql/internal
 308         < database/sql/driver
 309         < database/sql;
 310
 311         # images
 312         FMT, compress/lzw, compress/zlib
 313         < image/color
 314         < image, image/color/palette
 315         < image/internal/imageutil
 316         < image/draw
 317         < image/gif, image/jpeg, image/png;
 318
 319         # cgo, delayed as long as possible.
 320         # If you add a dependency on CGO, you must add the package
 321         # to cgoPackages in cmd/dist/test.go as well.
 322         RUNTIME
 323         < C
 324         < runtime/cgo
 325         < CGO
 326         < runtime/msan, runtime/asan;
 327
 328         # runtime/race
 329         NONE < runtime/race/internal/amd64v1;
 330         NONE < runtime/race/internal/amd64v3;
 331         CGO, runtime/race/internal/amd64v1, runtime/race/internal/amd64v3 < runtime/race;
 332
 333         # Bulk of the standard library must not use cgo.
 334         # The prohibition stops at net and os/user.
 335         C !< fmt, go/types, CRYPTO-MATH, log/slog;
 336
 337         CGO, OS
 338         < plugin;
 339
 340         CGO, FMT
 341         < os/user
 342         < archive/tar;
 343
 344         sync
 345         < internal/singleflight;
 346
 347         os
 348         < golang.org/x/net/dns/dnsmessage,
 349           golang.org/x/net/lif,
 350           golang.org/x/net/route;
 351
 352         os, runtime, strconv, sync, unsafe,
 353         internal/godebug
 354         < internal/intern;
 355
 356         internal/bytealg, internal/intern, internal/itoa, math/bits, sort, strconv
 357         < net/netip;
 358
 359         # net is unavoidable when doing any networking,
 360         # so large dependencies must be kept out.
 361         # This is a long-looking list but most of these
 362         # are small with few dependencies.
 363         CGO,
 364         golang.org/x/net/dns/dnsmessage,
 365         golang.org/x/net/lif,
 366         golang.org/x/net/route,
 367         internal/godebug,
 368         internal/nettrace,
 369         internal/poll,
 370         internal/singleflight,
 371         internal/race,
 372         net/netip,
 373         os
 374         < net;
 375
 376         fmt, unicode !< net;
 377         math/rand !< net; # net uses runtime instead
 378
 379         # NET is net plus net-helper packages.
 380         FMT, net
 381         < net/textproto;
 382
 383         mime, net/textproto, net/url
 384         < NET;
 385
 386         # logging - most packages should not import; http and up is allowed
 387         FMT, log/internal
 388         < log;
 389
 390         log, log/slog !< crypto/tls, database/sql, go/importer, testing;
 391
 392         FMT, log, net
 393         < log/syslog;
 394
 395         RUNTIME
 396         < log/slog/internal, log/slog/internal/buffer;
 397
 398         FMT,
 399         encoding, encoding/json,
 400         log, log/internal,
 401         log/slog/internal, log/slog/internal/buffer,
 402         slices
 403         < log/slog
 404         < log/slog/internal/slogtest, log/slog/internal/benchmarks;
 405
 406         NET, log
 407         < net/mail;
 408
 409         NONE < crypto/internal/boring/sig, crypto/internal/boring/syso;
 410         sync/atomic < crypto/internal/boring/bcache, crypto/internal/boring/fipstls;
 411         crypto/internal/boring/sig, crypto/internal/boring/fipstls < crypto/tls/fipsonly;
 412
 413         # CRYPTO is core crypto algorithms - no cgo, fmt, net.
 414         # Unfortunately, stuck with reflect via encoding/binary.
 415         crypto/internal/boring/sig,
 416         crypto/internal/boring/syso,
 417         encoding/binary,
 418         golang.org/x/sys/cpu,
 419         hash, embed
 420         < crypto
 421         < crypto/subtle
 422         < crypto/internal/alias
 423         < crypto/cipher;
 424
 425         crypto/cipher,
 426         crypto/internal/boring/bcache
 427         < crypto/internal/boring
 428         < crypto/boring;
 429
 430         crypto/internal/alias
 431         < crypto/internal/randutil
 432         < crypto/internal/nistec/fiat
 433         < crypto/internal/nistec
 434         < crypto/internal/edwards25519/field
 435         < crypto/internal/edwards25519;
 436
 437         crypto/boring
 438         < crypto/aes, crypto/des, crypto/hmac, crypto/md5, crypto/rc4,
 439           crypto/sha1, crypto/sha256, crypto/sha512;
 440
 441         crypto/boring, crypto/internal/edwards25519/field
 442         < crypto/ecdh;
 443
 444         crypto/aes,
 445         crypto/des,
 446         crypto/ecdh,
 447         crypto/hmac,
 448         crypto/internal/edwards25519,
 449         crypto/md5,
 450         crypto/rc4,
 451         crypto/sha1,
 452         crypto/sha256,
 453         crypto/sha512
 454         < CRYPTO;
 455
 456         CGO, fmt, net !< CRYPTO;
 457
 458         # CRYPTO-MATH is core bignum-based crypto - no cgo, net; fmt now ok.
 459         CRYPTO, FMT, math/big
 460         < crypto/internal/boring/bbig
 461         < crypto/rand
 462         < crypto/ed25519
 463         < encoding/asn1
 464         < golang.org/x/crypto/cryptobyte/asn1
 465         < golang.org/x/crypto/cryptobyte
 466         < crypto/internal/bigmod
 467         < crypto/dsa, crypto/elliptic, crypto/rsa
 468         < crypto/ecdsa
 469         < CRYPTO-MATH;
 470
 471         CGO, net !< CRYPTO-MATH;
 472
 473         # TLS, Prince of Dependencies.
 474         CRYPTO-MATH, NET, container/list, encoding/hex, encoding/pem
 475         < golang.org/x/crypto/internal/alias
 476         < golang.org/x/crypto/internal/subtle
 477         < golang.org/x/crypto/chacha20
 478         < golang.org/x/crypto/internal/poly1305
 479         < golang.org/x/crypto/chacha20poly1305
 480         < golang.org/x/crypto/hkdf
 481         < crypto/x509/internal/macos
 482         < crypto/x509/pkix;
 483
 484         crypto/internal/boring/fipstls, crypto/x509/pkix
 485         < crypto/x509
 486         < crypto/tls;
 487
 488         # crypto-aware packages
 489
 490         DEBUG, go/build, go/types, text/scanner, crypto/md5
 491         < internal/pkgbits
 492         < go/internal/gcimporter, go/internal/gccgoimporter, go/internal/srcimporter
 493         < go/importer;
 494
 495         NET, crypto/rand, mime/quotedprintable
 496         < mime/multipart;
 497
 498         crypto/tls
 499         < net/smtp;
 500
 501         crypto/rand
 502         < hash/maphash; # for purego implementation
 503
 504         # HTTP, King of Dependencies.
 505
 506         FMT
 507         < golang.org/x/net/http2/hpack
 508         < net/http/internal, net/http/internal/ascii, net/http/internal/testcert;
 509
 510         FMT, NET, container/list, encoding/binary, log
 511         < golang.org/x/text/transform
 512         < golang.org/x/text/unicode/norm
 513         < golang.org/x/text/unicode/bidi
 514         < golang.org/x/text/secure/bidirule
 515         < golang.org/x/net/idna
 516         < golang.org/x/net/http/httpguts, golang.org/x/net/http/httpproxy;
 517
 518         NET, crypto/tls
 519         < net/http/httptrace;
 520
 521         compress/gzip,
 522         golang.org/x/net/http/httpguts,
 523         golang.org/x/net/http/httpproxy,
 524         golang.org/x/net/http2/hpack,
 525         net/http/internal,
 526         net/http/internal/ascii,
 527         net/http/internal/testcert,
 528         net/http/httptrace,
 529         mime/multipart,
 530         log
 531         < net/http;
 532
 533         # HTTP-aware packages
 534
 535         encoding/json, net/http
 536         < expvar;
 537
 538         net/http, net/http/internal/ascii
 539         < net/http/cookiejar, net/http/httputil;
 540
 541         net/http, flag
 542         < net/http/httptest;
 543
 544         net/http, regexp
 545         < net/http/cgi
 546         < net/http/fcgi;
 547
 548         # Profiling
 549         FMT, compress/gzip, encoding/binary, text/tabwriter
 550         < runtime/pprof;
 551
 552         OS, compress/gzip, internal/lazyregexp
 553         < internal/profile;
 554
 555         html, internal/profile, net/http, runtime/pprof, runtime/trace
 556         < net/http/pprof;
 557
 558         # RPC
 559         encoding/gob, encoding/json, go/token, html/template, net/http
 560         < net/rpc
 561         < net/rpc/jsonrpc;
 562
 563         # System Information
 564         internal/cpu, sync
 565         < internal/sysinfo;
 566
 567         # Test-only
 568         log
 569         < testing/iotest
 570         < testing/fstest;
 571
 572         log/slog
 573         < testing/slogtest;
 574
 575         FMT, flag, math/rand
 576         < testing/quick;
 577
 578         FMT, DEBUG, flag, runtime/trace, internal/sysinfo, math/rand
 579         < testing;
 580
 581         FMT, crypto/sha256, encoding/json, go/ast, go/parser, go/token,
 582         internal/godebug, math/rand, encoding/hex, crypto/sha256
 583         < internal/fuzz;
 584
 585         internal/fuzz, internal/testlog, runtime/pprof, regexp
 586         < testing/internal/testdeps;
 587
 588         OS, flag, testing, internal/cfg, internal/platform, internal/goroot
 589         < internal/testenv;
 590
 591         OS, encoding/base64
 592         < internal/obscuretestdata;
 593
 594         CGO, OS, fmt
 595         < internal/testpty;
 596
 597         NET, testing, math/rand
 598         < golang.org/x/net/nettest;
 599
 600         syscall
 601         < os/exec/internal/fdtest;
 602
 603         FMT, container/heap, math/rand
 604         < internal/trace;
 605
 606         FMT
 607         < internal/diff, internal/txtar;
 608
 609         FMT, crypto/md5, encoding/binary, regexp, sort, text/tabwriter, unsafe,
 610         internal/coverage, internal/coverage/uleb128
 611         < internal/coverage/cmerge,
 612           internal/coverage/pods,
 613           internal/coverage/slicereader,
 614           internal/coverage/slicewriter;
 615
 616         internal/coverage/slicereader, internal/coverage/slicewriter
 617         < internal/coverage/stringtab
 618         < internal/coverage/decodecounter, internal/coverage/decodemeta,
 619           internal/coverage/encodecounter, internal/coverage/encodemeta;
 620
 621         internal/coverage/cmerge
 622         < internal/coverage/cformat;
 623
 624         runtime/debug,
 625         internal/coverage/calloc,
 626         internal/coverage/cformat,
 627         internal/coverage/decodecounter, internal/coverage/decodemeta,
 628         internal/coverage/encodecounter, internal/coverage/encodemeta,
 629         internal/coverage/pods
 630         < runtime/coverage;
 631 `
 632
 633 // listStdPkgs returns the same list of packages as "go list std".
 634 func listStdPkgs(goroot string) ([]string, error) {
 635         // Based on cmd/go's matchPackages function.
 636         var pkgs []string
 637
 638         src := filepath.Join(goroot, "src") + string(filepath.Separator)
 639         walkFn := func(path string, d fs.DirEntry, err error) error {
 640                 if err != nil || !d.IsDir() || path == src {
 641                         return nil
 642                 }
 643
 644                 base := filepath.Base(path)
 645                 if strings.HasPrefix(base, ".") || strings.HasPrefix(base, "_") || base == "testdata" {
 646                         return filepath.SkipDir
 647                 }
 648
 649                 name := filepath.ToSlash(path[len(src):])
 650                 if name == "builtin" || name == "cmd" {
 651                         return filepath.SkipDir
 652                 }
 653
 654                 pkgs = append(pkgs, strings.TrimPrefix(name, "vendor/"))
 655                 return nil
 656         }
 657         if err := filepath.WalkDir(src, walkFn); err != nil {
 658                 return nil, err
 659         }
 660         return pkgs, nil
 661 }
 662
 663 func TestDependencies(t *testing.T) {
 664         if !testenv.HasSrc() {
 665                 // Tests run in a limited file system and we do not
 666                 // provide access to every source file.
 667                 t.Skipf("skipping on %s/%s, missing full GOROOT", runtime.GOOS, runtime.GOARCH)
 668         }
 669
 670         ctxt := Default
 671         all, err := listStdPkgs(ctxt.GOROOT)
 672         if err != nil {
 673                 t.Fatal(err)
 674         }
 675         sort.Strings(all)
 676
 677         sawImport := map[string]map[string]bool{} // from package => to package => true
 678         policy := depsPolicy(t)
 679
 680         for _, pkg := range all {
 681                 imports, err := findImports(pkg)
 682                 if err != nil {
 683                         t.Error(err)
 684                         continue
 685                 }
 686                 if sawImport[pkg] == nil {
 687                         sawImport[pkg] = map[string]bool{}
 688                 }
 689                 var bad []string
 690                 for _, imp := range imports {
 691                         sawImport[pkg][imp] = true
 692                         if !policy.HasEdge(pkg, imp) {
 693                                 bad = append(bad, imp)
 694                         }
 695                 }
 696                 if bad != nil {
 697                         t.Errorf("unexpected dependency: %s imports %v", pkg, bad)
 698                 }
 699         }
 700 }
 701
 702 var buildIgnore = []byte("\n//go:build ignore")
 703
 704 func findImports(pkg string) ([]string, error) {
 705         vpkg := pkg
 706         if strings.HasPrefix(pkg, "golang.org") {
 707                 vpkg = "vendor/" + pkg
 708         }
 709         dir := filepath.Join(Default.GOROOT, "src", vpkg)
 710         files, err := os.ReadDir(dir)
 711         if err != nil {
 712                 return nil, err
 713         }
 714         var imports []string
 715         var haveImport = map[string]bool{}
 716         if pkg == "crypto/internal/boring" {
 717                 haveImport["C"] = true // kludge: prevent C from appearing in crypto/internal/boring imports
 718         }
 719         fset := token.NewFileSet()
 720         for _, file := range files {
 721                 name := file.Name()
 722                 if name == "slice_go14.go" || name == "slice_go18.go" {
 723                         // These files are for compiler bootstrap with older versions of Go and not built in the standard build.
 724                         continue
 725                 }
 726                 if !strings.HasSuffix(name, ".go") || strings.HasSuffix(name, "_test.go") {
 727                         continue
 728                 }
 729                 info := fileInfo{
 730                         name: filepath.Join(dir, name),
 731                         fset: fset,
 732                 }
 733                 f, err := os.Open(info.name)
 734                 if err != nil {
 735                         return nil, err
 736                 }
 737                 err = readGoInfo(f, &info)
 738                 f.Close()
 739                 if err != nil {
 740                         return nil, fmt.Errorf("reading %v: %v", name, err)
 741                 }
 742                 if info.parsed.Name.Name == "main" {
 743                         continue
 744                 }
 745                 if bytes.Contains(info.header, buildIgnore) {
 746                         continue
 747                 }
 748                 for _, imp := range info.imports {
 749                         path := imp.path
 750                         if !haveImport[path] {
 751                                 haveImport[path] = true
 752                                 imports = append(imports, path)
 753                         }
 754                 }
 755         }
 756         sort.Strings(imports)
 757         return imports, nil
 758 }
 759
 760 // depsPolicy returns a map m such that m[p][d] == true when p can import d.
 761 func depsPolicy(t *testing.T) *dag.Graph {
 762         g, err := dag.Parse(depsRules)
 763         if err != nil {
 764                 t.Fatal(err)
 765         }
 766         return g
 767 }
 768
 769 // TestStdlibLowercase tests that all standard library package names are
 770 // lowercase. See Issue 40065.
 771 func TestStdlibLowercase(t *testing.T) {
 772         if !testenv.HasSrc() {
 773                 t.Skipf("skipping on %s/%s, missing full GOROOT", runtime.GOOS, runtime.GOARCH)
 774         }
 775
 776         ctxt := Default
 777         all, err := listStdPkgs(ctxt.GOROOT)
 778         if err != nil {
 779                 t.Fatal(err)
 780         }
 781
 782         for _, pkgname := range all {
 783                 if strings.ToLower(pkgname) != pkgname {
 784                         t.Errorf("package %q should not use upper-case path", pkgname)
 785                 }
 786         }
 787 }
 788
 789 // TestFindImports tests that findImports works.  See #43249.
 790 func TestFindImports(t *testing.T) {
 791         imports, err := findImports("go/build")
 792         if err != nil {
 793                 t.Fatal(err)
 794         }
 795         t.Logf("go/build imports %q", imports)
 796         want := []string{"bytes", "os", "path/filepath", "strings"}
 797 wantLoop:
 798         for _, w := range want {
 799                 for _, imp := range imports {
 800                         if imp == w {
 801                                 continue wantLoop
 802                         }
 803                 }
 804                 t.Errorf("expected to find %q in import list", w)
 805         }
 806 }