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         < cmp, 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         # These packages depend only on internal/goarch and unsafe.
  53         internal/goarch, unsafe
  54         < internal/abi;
  55
  56         unsafe < maps;
  57
  58         # RUNTIME is the core runtime group of packages, all of them very light-weight.
  59         internal/abi, internal/cpu, internal/goarch,
  60         internal/coverage/rtcov, internal/godebugs, internal/goexperiment,
  61         internal/goos, unsafe
  62         < internal/bytealg
  63         < internal/itoa
  64         < internal/unsafeheader
  65         < runtime/internal/sys
  66         < runtime/internal/syscall
  67         < runtime/internal/atomic
  68         < runtime/internal/math
  69         < runtime
  70         < sync/atomic
  71         < internal/race
  72         < sync
  73         < internal/bisect
  74         < internal/godebug
  75         < internal/reflectlite
  76         < errors
  77         < internal/oserror, math/bits
  78         < RUNTIME;
  79
  80         RUNTIME
  81         < sort
  82         < container/heap;
  83
  84         RUNTIME
  85         < io;
  86
  87         RUNTIME
  88         < arena;
  89
  90         syscall !< io;
  91         reflect !< sort;
  92
  93         RUNTIME, unicode/utf8
  94         < path;
  95
  96         unicode !< path;
  97
  98         # SYSCALL is RUNTIME plus the packages necessary for basic system calls.
  99         RUNTIME, unicode/utf8, unicode/utf16
 100         < internal/syscall/windows/sysdll, syscall/js
 101         < syscall
 102         < internal/syscall/unix, internal/syscall/windows, internal/syscall/windows/registry
 103         < internal/syscall/execenv
 104         < SYSCALL;
 105
 106         # TIME is SYSCALL plus the core packages about time, including context.
 107         SYSCALL
 108         < time/tzdata
 109         < time
 110         < context
 111         < TIME;
 112
 113         TIME, io, path, sort
 114         < io/fs;
 115
 116         # MATH is RUNTIME plus the basic math packages.
 117         RUNTIME
 118         < math
 119         < MATH;
 120
 121         unicode !< math;
 122
 123         MATH
 124         < math/cmplx;
 125
 126         MATH
 127         < math/rand;
 128
 129         MATH
 130         < runtime/metrics;
 131
 132         MATH, unicode/utf8
 133         < strconv;
 134
 135         unicode !< strconv;
 136
 137         # STR is basic string and buffer manipulation.
 138         RUNTIME, io, unicode/utf8, unicode/utf16, unicode
 139         < bytes, strings
 140         < bufio;
 141
 142         bufio, path, strconv
 143         < STR;
 144
 145         # OS is basic OS access, including helpers (path/filepath, os/exec, etc).
 146         # OS includes string routines, but those must be layered above package os.
 147         # OS does not include reflection.
 148         io/fs
 149         < internal/testlog
 150         < internal/poll
 151         < internal/safefilepath
 152         < os
 153         < os/signal;
 154
 155         io/fs
 156         < embed;
 157
 158         unicode, fmt !< net, os, os/signal;
 159
 160         os/signal, STR
 161         < path/filepath
 162         < io/ioutil;
 163
 164         path/filepath, internal/godebug < os/exec;
 165
 166         io/ioutil, os/exec, os/signal
 167         < OS;
 168
 169         reflect !< OS;
 170
 171         OS
 172         < golang.org/x/sys/cpu;
 173
 174         # FMT is OS (which includes string routines) plus reflect and fmt.
 175         # It does not include package log, which should be avoided in core packages.
 176         arena, strconv, unicode
 177         < reflect;
 178
 179         os, reflect
 180         < internal/fmtsort
 181         < fmt;
 182
 183         OS, fmt
 184         < FMT;
 185
 186         log !< FMT;
 187
 188         # Misc packages needing only FMT.
 189         FMT
 190         < html,
 191           internal/dag,
 192           internal/goroot,
 193           internal/types/errors,
 194           mime/quotedprintable,
 195           net/internal/socktest,
 196           net/url,
 197           runtime/trace,
 198           text/scanner,
 199           text/tabwriter;
 200
 201         io, reflect
 202         < internal/saferio;
 203
 204         # encodings
 205         # core ones do not use fmt.
 206         io, strconv
 207         < encoding;
 208
 209         encoding, reflect
 210         < encoding/binary
 211         < encoding/base32, encoding/base64;
 212
 213         FMT, encoding < flag;
 214
 215         fmt !< encoding/base32, encoding/base64;
 216
 217         FMT, encoding/base32, encoding/base64, internal/saferio
 218         < encoding/ascii85, encoding/csv, encoding/gob, encoding/hex,
 219           encoding/json, encoding/pem, encoding/xml, mime;
 220
 221         # hashes
 222         io
 223         < hash
 224         < hash/adler32, hash/crc32, hash/crc64, hash/fnv;
 225
 226         # slices depends on unsafe for overlapping check, cmp for comparison
 227         # semantics, and math/bits for # calculating bitlength of numbers.
 228         unsafe, cmp, math/bits
 229         < slices;
 230
 231         # math/big
 232         FMT, encoding/binary, math/rand
 233         < math/big;
 234
 235         # compression
 236         FMT, encoding/binary, hash/adler32, hash/crc32
 237         < compress/bzip2, compress/flate, compress/lzw, internal/zstd
 238         < archive/zip, compress/gzip, compress/zlib;
 239
 240         # templates
 241         FMT
 242         < text/template/parse;
 243
 244         net/url, text/template/parse
 245         < text/template
 246         < internal/lazytemplate;
 247
 248         encoding/json, html, text/template
 249         < html/template;
 250
 251         # regexp
 252         FMT
 253         < regexp/syntax
 254         < regexp
 255         < internal/lazyregexp;
 256
 257         # suffix array
 258         encoding/binary, regexp
 259         < index/suffixarray;
 260
 261         # executable parsing
 262         FMT, encoding/binary, compress/zlib, internal/saferio, internal/zstd
 263         < runtime/debug
 264         < debug/dwarf
 265         < debug/elf, debug/gosym, debug/macho, debug/pe, debug/plan9obj, internal/xcoff
 266         < debug/buildinfo
 267         < DEBUG;
 268
 269         # go parser and friends.
 270         FMT
 271         < go/token
 272         < go/scanner
 273         < go/ast
 274         < go/internal/typeparams;
 275
 276         FMT
 277         < go/build/constraint, go/doc/comment;
 278
 279         go/internal/typeparams, go/build/constraint
 280         < go/parser;
 281
 282         go/doc/comment, go/parser, text/tabwriter
 283         < go/printer
 284         < go/format;
 285
 286         math/big, go/token
 287         < go/constant;
 288
 289         container/heap, go/constant, go/parser, internal/types/errors
 290         < go/types;
 291
 292         # The vast majority of standard library packages should not be resorting to regexp.
 293         # go/types is a good chokepoint. It shouldn't use regexp, nor should anything
 294         # that is low-enough level to be used by go/types.
 295         regexp !< go/types;
 296
 297         go/doc/comment, go/parser, internal/lazyregexp, text/template
 298         < go/doc;
 299
 300         FMT, internal/goexperiment
 301         < internal/buildcfg;
 302
 303         go/build/constraint, go/doc, go/parser, internal/buildcfg, internal/goroot, internal/goversion, internal/platform
 304         < go/build;
 305
 306         # databases
 307         FMT
 308         < database/sql/internal
 309         < database/sql/driver
 310         < database/sql;
 311
 312         # images
 313         FMT, compress/lzw, compress/zlib
 314         < image/color
 315         < image, image/color/palette
 316         < image/internal/imageutil
 317         < image/draw
 318         < image/gif, image/jpeg, image/png;
 319
 320         # cgo, delayed as long as possible.
 321         # If you add a dependency on CGO, you must add the package
 322         # to cgoPackages in cmd/dist/test.go as well.
 323         RUNTIME
 324         < C
 325         < runtime/cgo
 326         < CGO
 327         < runtime/msan, runtime/asan;
 328
 329         # runtime/race
 330         NONE < runtime/race/internal/amd64v1;
 331         NONE < runtime/race/internal/amd64v3;
 332         CGO, runtime/race/internal/amd64v1, runtime/race/internal/amd64v3 < runtime/race;
 333
 334         # Bulk of the standard library must not use cgo.
 335         # The prohibition stops at net and os/user.
 336         C !< fmt, go/types, CRYPTO-MATH, log/slog;
 337
 338         CGO, OS
 339         < plugin;
 340
 341         CGO, FMT
 342         < os/user
 343         < archive/tar;
 344
 345         sync
 346         < internal/singleflight;
 347
 348         os
 349         < golang.org/x/net/dns/dnsmessage,
 350           golang.org/x/net/lif,
 351           golang.org/x/net/route;
 352
 353         os, runtime, strconv, sync, unsafe,
 354         internal/godebug
 355         < internal/intern;
 356
 357         internal/bytealg, internal/intern, internal/itoa, math/bits, sort, strconv
 358         < net/netip;
 359
 360         # net is unavoidable when doing any networking,
 361         # so large dependencies must be kept out.
 362         # This is a long-looking list but most of these
 363         # are small with few dependencies.
 364         CGO,
 365         golang.org/x/net/dns/dnsmessage,
 366         golang.org/x/net/lif,
 367         golang.org/x/net/route,
 368         internal/godebug,
 369         internal/nettrace,
 370         internal/poll,
 371         internal/singleflight,
 372         internal/race,
 373         net/netip,
 374         os
 375         < net;
 376
 377         fmt, unicode !< net;
 378         math/rand !< net; # net uses runtime instead
 379
 380         # NET is net plus net-helper packages.
 381         FMT, net
 382         < net/textproto;
 383
 384         mime, net/textproto, net/url
 385         < NET;
 386
 387         # logging - most packages should not import; http and up is allowed
 388         FMT, log/internal
 389         < log;
 390
 391         log, log/slog !< crypto/tls, database/sql, go/importer, testing;
 392
 393         FMT, log, net
 394         < log/syslog;
 395
 396         RUNTIME
 397         < log/slog/internal, log/slog/internal/buffer;
 398
 399         FMT,
 400         encoding, encoding/json,
 401         log, log/internal,
 402         log/slog/internal, log/slog/internal/buffer,
 403         slices
 404         < log/slog
 405         < log/slog/internal/slogtest, log/slog/internal/benchmarks;
 406
 407         NET, log
 408         < net/mail;
 409
 410         NONE < crypto/internal/boring/sig, crypto/internal/boring/syso;
 411         sync/atomic < crypto/internal/boring/bcache, crypto/internal/boring/fipstls;
 412         crypto/internal/boring/sig, crypto/internal/boring/fipstls < crypto/tls/fipsonly;
 413
 414         # CRYPTO is core crypto algorithms - no cgo, fmt, net.
 415         # Unfortunately, stuck with reflect via encoding/binary.
 416         crypto/internal/boring/sig,
 417         crypto/internal/boring/syso,
 418         encoding/binary,
 419         golang.org/x/sys/cpu,
 420         hash, embed
 421         < crypto
 422         < crypto/subtle
 423         < crypto/internal/alias
 424         < crypto/cipher;
 425
 426         crypto/cipher,
 427         crypto/internal/boring/bcache
 428         < crypto/internal/boring
 429         < crypto/boring;
 430
 431         crypto/internal/alias
 432         < crypto/internal/randutil
 433         < crypto/internal/nistec/fiat
 434         < crypto/internal/nistec
 435         < crypto/internal/edwards25519/field
 436         < crypto/internal/edwards25519;
 437
 438         crypto/boring
 439         < crypto/aes, crypto/des, crypto/hmac, crypto/md5, crypto/rc4,
 440           crypto/sha1, crypto/sha256, crypto/sha512;
 441
 442         crypto/boring, crypto/internal/edwards25519/field
 443         < crypto/ecdh;
 444
 445         crypto/aes,
 446         crypto/des,
 447         crypto/ecdh,
 448         crypto/hmac,
 449         crypto/internal/edwards25519,
 450         crypto/md5,
 451         crypto/rc4,
 452         crypto/sha1,
 453         crypto/sha256,
 454         crypto/sha512
 455         < CRYPTO;
 456
 457         CGO, fmt, net !< CRYPTO;
 458
 459         # CRYPTO-MATH is core bignum-based crypto - no cgo, net; fmt now ok.
 460         CRYPTO, FMT, math/big
 461         < crypto/internal/boring/bbig
 462         < crypto/rand
 463         < crypto/ed25519
 464         < encoding/asn1
 465         < golang.org/x/crypto/cryptobyte/asn1
 466         < golang.org/x/crypto/cryptobyte
 467         < crypto/internal/bigmod
 468         < crypto/dsa, crypto/elliptic, crypto/rsa
 469         < crypto/ecdsa
 470         < CRYPTO-MATH;
 471
 472         CGO, net !< CRYPTO-MATH;
 473
 474         # TLS, Prince of Dependencies.
 475         CRYPTO-MATH, NET, container/list, encoding/hex, encoding/pem
 476         < golang.org/x/crypto/internal/alias
 477         < golang.org/x/crypto/internal/subtle
 478         < golang.org/x/crypto/chacha20
 479         < golang.org/x/crypto/internal/poly1305
 480         < golang.org/x/crypto/chacha20poly1305
 481         < golang.org/x/crypto/hkdf
 482         < crypto/x509/internal/macos
 483         < crypto/x509/pkix;
 484
 485         crypto/internal/boring/fipstls, crypto/x509/pkix
 486         < crypto/x509
 487         < crypto/tls;
 488
 489         # crypto-aware packages
 490
 491         DEBUG, go/build, go/types, text/scanner, crypto/md5
 492         < internal/pkgbits
 493         < go/internal/gcimporter, go/internal/gccgoimporter, go/internal/srcimporter
 494         < go/importer;
 495
 496         NET, crypto/rand, mime/quotedprintable
 497         < mime/multipart;
 498
 499         crypto/tls
 500         < net/smtp;
 501
 502         crypto/rand
 503         < hash/maphash; # for purego implementation
 504
 505         # HTTP, King of Dependencies.
 506
 507         FMT
 508         < golang.org/x/net/http2/hpack
 509         < net/http/internal, net/http/internal/ascii, net/http/internal/testcert;
 510
 511         FMT, NET, container/list, encoding/binary, log
 512         < golang.org/x/text/transform
 513         < golang.org/x/text/unicode/norm
 514         < golang.org/x/text/unicode/bidi
 515         < golang.org/x/text/secure/bidirule
 516         < golang.org/x/net/idna
 517         < golang.org/x/net/http/httpguts, golang.org/x/net/http/httpproxy;
 518
 519         NET, crypto/tls
 520         < net/http/httptrace;
 521
 522         compress/gzip,
 523         golang.org/x/net/http/httpguts,
 524         golang.org/x/net/http/httpproxy,
 525         golang.org/x/net/http2/hpack,
 526         net/http/internal,
 527         net/http/internal/ascii,
 528         net/http/internal/testcert,
 529         net/http/httptrace,
 530         mime/multipart,
 531         log
 532         < net/http;
 533
 534         # HTTP-aware packages
 535
 536         encoding/json, net/http
 537         < expvar;
 538
 539         net/http, net/http/internal/ascii
 540         < net/http/cookiejar, net/http/httputil;
 541
 542         net/http, flag
 543         < net/http/httptest;
 544
 545         net/http, regexp
 546         < net/http/cgi
 547         < net/http/fcgi;
 548
 549         # Profiling
 550         FMT, compress/gzip, encoding/binary, text/tabwriter
 551         < runtime/pprof;
 552
 553         OS, compress/gzip, internal/lazyregexp
 554         < internal/profile;
 555
 556         html, internal/profile, net/http, runtime/pprof, runtime/trace
 557         < net/http/pprof;
 558
 559         # RPC
 560         encoding/gob, encoding/json, go/token, html/template, net/http
 561         < net/rpc
 562         < net/rpc/jsonrpc;
 563
 564         # System Information
 565         internal/cpu, sync
 566         < internal/sysinfo;
 567
 568         # Test-only
 569         log
 570         < testing/iotest
 571         < testing/fstest;
 572
 573         log/slog
 574         < testing/slogtest;
 575
 576         FMT, flag, math/rand
 577         < testing/quick;
 578
 579         FMT, DEBUG, flag, runtime/trace, internal/sysinfo, math/rand
 580         < testing;
 581
 582         FMT, crypto/sha256, encoding/json, go/ast, go/parser, go/token,
 583         internal/godebug, math/rand, encoding/hex, crypto/sha256
 584         < internal/fuzz;
 585
 586         internal/fuzz, internal/testlog, runtime/pprof, regexp
 587         < testing/internal/testdeps;
 588
 589         OS, flag, testing, internal/cfg, internal/platform, internal/goroot
 590         < internal/testenv;
 591
 592         OS, encoding/base64
 593         < internal/obscuretestdata;
 594
 595         CGO, OS, fmt
 596         < internal/testpty;
 597
 598         NET, testing, math/rand
 599         < golang.org/x/net/nettest;
 600
 601         syscall
 602         < os/exec/internal/fdtest;
 603
 604         FMT, container/heap, math/rand
 605         < internal/trace;
 606
 607         FMT
 608         < internal/diff, internal/txtar;
 609
 610         FMT, crypto/md5, encoding/binary, regexp, sort, text/tabwriter, unsafe,
 611         internal/coverage, internal/coverage/uleb128
 612         < internal/coverage/cmerge,
 613           internal/coverage/pods,
 614           internal/coverage/slicereader,
 615           internal/coverage/slicewriter;
 616
 617         internal/coverage/slicereader, internal/coverage/slicewriter
 618         < internal/coverage/stringtab
 619         < internal/coverage/decodecounter, internal/coverage/decodemeta,
 620           internal/coverage/encodecounter, internal/coverage/encodemeta;
 621
 622         internal/coverage/cmerge
 623         < internal/coverage/cformat;
 624
 625     encoding/json,
 626         runtime/debug,
 627         internal/coverage/calloc,
 628         internal/coverage/cformat,
 629         internal/coverage/decodecounter, internal/coverage/decodemeta,
 630         internal/coverage/encodecounter, internal/coverage/encodemeta,
 631         internal/coverage/pods
 632         < runtime/coverage;
 633 `
 634
 635 // listStdPkgs returns the same list of packages as "go list std".
 636 func listStdPkgs(goroot string) ([]string, error) {
 637         // Based on cmd/go's matchPackages function.
 638         var pkgs []string
 639
 640         src := filepath.Join(goroot, "src") + string(filepath.Separator)
 641         walkFn := func(path string, d fs.DirEntry, err error) error {
 642                 if err != nil || !d.IsDir() || path == src {
 643                         return nil
 644                 }
 645
 646                 base := filepath.Base(path)
 647                 if strings.HasPrefix(base, ".") || strings.HasPrefix(base, "_") || base == "testdata" {
 648                         return filepath.SkipDir
 649                 }
 650
 651                 name := filepath.ToSlash(path[len(src):])
 652                 if name == "builtin" || name == "cmd" {
 653                         return filepath.SkipDir
 654                 }
 655
 656                 pkgs = append(pkgs, strings.TrimPrefix(name, "vendor/"))
 657                 return nil
 658         }
 659         if err := filepath.WalkDir(src, walkFn); err != nil {
 660                 return nil, err
 661         }
 662         return pkgs, nil
 663 }
 664
 665 func TestDependencies(t *testing.T) {
 666         if !testenv.HasSrc() {
 667                 // Tests run in a limited file system and we do not
 668                 // provide access to every source file.
 669                 t.Skipf("skipping on %s/%s, missing full GOROOT", runtime.GOOS, runtime.GOARCH)
 670         }
 671
 672         ctxt := Default
 673         all, err := listStdPkgs(ctxt.GOROOT)
 674         if err != nil {
 675                 t.Fatal(err)
 676         }
 677         sort.Strings(all)
 678
 679         sawImport := map[string]map[string]bool{} // from package => to package => true
 680         policy := depsPolicy(t)
 681
 682         for _, pkg := range all {
 683                 imports, err := findImports(pkg)
 684                 if err != nil {
 685                         t.Error(err)
 686                         continue
 687                 }
 688                 if sawImport[pkg] == nil {
 689                         sawImport[pkg] = map[string]bool{}
 690                 }
 691                 var bad []string
 692                 for _, imp := range imports {
 693                         sawImport[pkg][imp] = true
 694                         if !policy.HasEdge(pkg, imp) {
 695                                 bad = append(bad, imp)
 696                         }
 697                 }
 698                 if bad != nil {
 699                         t.Errorf("unexpected dependency: %s imports %v", pkg, bad)
 700                 }
 701         }
 702 }
 703
 704 var buildIgnore = []byte("\n//go:build ignore")
 705
 706 func findImports(pkg string) ([]string, error) {
 707         vpkg := pkg
 708         if strings.HasPrefix(pkg, "golang.org") {
 709                 vpkg = "vendor/" + pkg
 710         }
 711         dir := filepath.Join(Default.GOROOT, "src", vpkg)
 712         files, err := os.ReadDir(dir)
 713         if err != nil {
 714                 return nil, err
 715         }
 716         var imports []string
 717         var haveImport = map[string]bool{}
 718         if pkg == "crypto/internal/boring" {
 719                 haveImport["C"] = true // kludge: prevent C from appearing in crypto/internal/boring imports
 720         }
 721         fset := token.NewFileSet()
 722         for _, file := range files {
 723                 name := file.Name()
 724                 if name == "slice_go14.go" || name == "slice_go18.go" {
 725                         // These files are for compiler bootstrap with older versions of Go and not built in the standard build.
 726                         continue
 727                 }
 728                 if !strings.HasSuffix(name, ".go") || strings.HasSuffix(name, "_test.go") {
 729                         continue
 730                 }
 731                 info := fileInfo{
 732                         name: filepath.Join(dir, name),
 733                         fset: fset,
 734                 }
 735                 f, err := os.Open(info.name)
 736                 if err != nil {
 737                         return nil, err
 738                 }
 739                 err = readGoInfo(f, &info)
 740                 f.Close()
 741                 if err != nil {
 742                         return nil, fmt.Errorf("reading %v: %v", name, err)
 743                 }
 744                 if info.parsed.Name.Name == "main" {
 745                         continue
 746                 }
 747                 if bytes.Contains(info.header, buildIgnore) {
 748                         continue
 749                 }
 750                 for _, imp := range info.imports {
 751                         path := imp.path
 752                         if !haveImport[path] {
 753                                 haveImport[path] = true
 754                                 imports = append(imports, path)
 755                         }
 756                 }
 757         }
 758         sort.Strings(imports)
 759         return imports, nil
 760 }
 761
 762 // depsPolicy returns a map m such that m[p][d] == true when p can import d.
 763 func depsPolicy(t *testing.T) *dag.Graph {
 764         g, err := dag.Parse(depsRules)
 765         if err != nil {
 766                 t.Fatal(err)
 767         }
 768         return g
 769 }
 770
 771 // TestStdlibLowercase tests that all standard library package names are
 772 // lowercase. See Issue 40065.
 773 func TestStdlibLowercase(t *testing.T) {
 774         if !testenv.HasSrc() {
 775                 t.Skipf("skipping on %s/%s, missing full GOROOT", runtime.GOOS, runtime.GOARCH)
 776         }
 777
 778         ctxt := Default
 779         all, err := listStdPkgs(ctxt.GOROOT)
 780         if err != nil {
 781                 t.Fatal(err)
 782         }
 783
 784         for _, pkgname := range all {
 785                 if strings.ToLower(pkgname) != pkgname {
 786                         t.Errorf("package %q should not use upper-case path", pkgname)
 787                 }
 788         }
 789 }
 790
 791 // TestFindImports tests that findImports works.  See #43249.
 792 func TestFindImports(t *testing.T) {
 793         imports, err := findImports("go/build")
 794         if err != nil {
 795                 t.Fatal(err)
 796         }
 797         t.Logf("go/build imports %q", imports)
 798         want := []string{"bytes", "os", "path/filepath", "strings"}
 799 wantLoop:
 800         for _, w := range want {
 801                 for _, imp := range imports {
 802                         if imp == w {
 803                                 continue wantLoop
 804                         }
 805                 }
 806                 t.Errorf("expected to find %q in import list", w)
 807         }
 808 }