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