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         # slices depends on unsafe for overlapping check, cmp for comparison
  81         # semantics, and math/bits for # calculating bitlength of numbers.
  82         unsafe, cmp, math/bits
  83         < slices;
  84
  85         RUNTIME, slices
  86         < sort;
  87
  88         sort
  89         < container/heap;
  90
  91         RUNTIME
  92         < io;
  93
  94         RUNTIME
  95         < arena;
  96
  97         syscall !< io;
  98         reflect !< sort;
  99
 100         RUNTIME, unicode/utf8
 101         < path;
 102
 103         unicode !< path;
 104
 105         # SYSCALL is RUNTIME plus the packages necessary for basic system calls.
 106         RUNTIME, unicode/utf8, unicode/utf16
 107         < internal/syscall/windows/sysdll, syscall/js
 108         < syscall
 109         < internal/syscall/unix, internal/syscall/windows, internal/syscall/windows/registry
 110         < internal/syscall/execenv
 111         < SYSCALL;
 112
 113         # TIME is SYSCALL plus the core packages about time, including context.
 114         SYSCALL
 115         < time/tzdata
 116         < time
 117         < context
 118         < TIME;
 119
 120         TIME, io, path, sort
 121         < io/fs;
 122
 123         # MATH is RUNTIME plus the basic math packages.
 124         RUNTIME
 125         < math
 126         < MATH;
 127
 128         unicode !< math;
 129
 130         MATH
 131         < math/cmplx;
 132
 133         MATH
 134         < math/rand, math/rand/v2;
 135
 136         MATH
 137         < runtime/metrics;
 138
 139         MATH, unicode/utf8
 140         < strconv;
 141
 142         unicode !< strconv;
 143
 144         # STR is basic string and buffer manipulation.
 145         RUNTIME, io, unicode/utf8, unicode/utf16, unicode
 146         < bytes, strings
 147         < bufio;
 148
 149         bufio, path, strconv
 150         < STR;
 151
 152         # OS is basic OS access, including helpers (path/filepath, os/exec, etc).
 153         # OS includes string routines, but those must be layered above package os.
 154         # OS does not include reflection.
 155         io/fs
 156         < internal/testlog
 157         < internal/poll
 158         < internal/safefilepath
 159         < os
 160         < os/signal;
 161
 162         io/fs
 163         < embed;
 164
 165         unicode, fmt !< net, os, os/signal;
 166
 167         os/signal, STR
 168         < path/filepath
 169         < io/ioutil;
 170
 171         path/filepath, internal/godebug < os/exec;
 172
 173         io/ioutil, os/exec, os/signal
 174         < OS;
 175
 176         reflect !< OS;
 177
 178         OS
 179         < golang.org/x/sys/cpu;
 180
 181         # FMT is OS (which includes string routines) plus reflect and fmt.
 182         # It does not include package log, which should be avoided in core packages.
 183         arena, strconv, unicode
 184         < reflect;
 185
 186         os, reflect
 187         < internal/fmtsort
 188         < fmt;
 189
 190         OS, fmt
 191         < FMT;
 192
 193         log !< FMT;
 194
 195         # Misc packages needing only FMT.
 196         FMT
 197         < html,
 198           internal/dag,
 199           internal/goroot,
 200           internal/types/errors,
 201           mime/quotedprintable,
 202           net/internal/socktest,
 203           net/url,
 204           runtime/trace,
 205           text/scanner,
 206           text/tabwriter;
 207
 208         io, reflect
 209         < internal/saferio;
 210
 211         # encodings
 212         # core ones do not use fmt.
 213         io, strconv, slices
 214         < encoding;
 215
 216         encoding, reflect
 217         < encoding/binary
 218         < encoding/base32, encoding/base64;
 219
 220         FMT, encoding < flag;
 221
 222         fmt !< encoding/base32, encoding/base64;
 223
 224         FMT, encoding/base32, encoding/base64, internal/saferio
 225         < encoding/ascii85, encoding/csv, encoding/gob, encoding/hex,
 226           encoding/json, encoding/pem, encoding/xml, mime;
 227
 228         # hashes
 229         io
 230         < hash
 231         < hash/adler32, hash/crc32, hash/crc64, hash/fnv;
 232
 233         # math/big
 234         FMT, encoding/binary, math/rand
 235         < math/big;
 236
 237         # compression
 238         FMT, encoding/binary, hash/adler32, hash/crc32
 239         < compress/bzip2, compress/flate, compress/lzw, internal/zstd
 240         < archive/zip, compress/gzip, compress/zlib;
 241
 242         # templates
 243         FMT
 244         < text/template/parse;
 245
 246         net/url, text/template/parse
 247         < text/template
 248         < internal/lazytemplate;
 249
 250         # regexp
 251         FMT
 252         < regexp/syntax
 253         < regexp
 254         < internal/lazyregexp;
 255
 256         encoding/json, html, text/template, regexp
 257         < html/template;
 258
 259         # suffix array
 260         encoding/binary, regexp
 261         < index/suffixarray;
 262
 263         # executable parsing
 264         FMT, encoding/binary, compress/zlib, internal/saferio, internal/zstd
 265         < runtime/debug
 266         < debug/dwarf
 267         < debug/elf, debug/gosym, debug/macho, debug/pe, debug/plan9obj, internal/xcoff
 268         < debug/buildinfo
 269         < DEBUG;
 270
 271         # go parser and friends.
 272         FMT
 273         < go/token
 274         < go/scanner
 275         < go/ast
 276         < go/internal/typeparams;
 277
 278         FMT
 279         < go/build/constraint, go/doc/comment;
 280
 281         go/internal/typeparams, go/build/constraint
 282         < go/parser;
 283
 284         go/doc/comment, go/parser, text/tabwriter
 285         < go/printer
 286         < go/format;
 287
 288         math/big, go/token
 289         < go/constant;
 290
 291         FMT, internal/goexperiment
 292         < internal/buildcfg;
 293
 294         container/heap, go/constant, go/parser, internal/buildcfg, internal/goversion, internal/types/errors
 295         < go/types;
 296
 297         # The vast majority of standard library packages should not be resorting to regexp.
 298         # go/types is a good chokepoint. It shouldn't use regexp, nor should anything
 299         # that is low-enough level to be used by go/types.
 300         regexp !< go/types;
 301
 302         go/doc/comment, go/parser, internal/lazyregexp, text/template
 303         < go/doc;
 304
 305         go/build/constraint, go/doc, go/parser, internal/buildcfg, internal/goroot, internal/goversion, internal/platform
 306         < go/build;
 307
 308         # databases
 309         FMT
 310         < database/sql/internal
 311         < database/sql/driver
 312         < database/sql;
 313
 314         # images
 315         FMT, compress/lzw, compress/zlib
 316         < image/color
 317         < image, image/color/palette
 318         < image/internal/imageutil
 319         < image/draw
 320         < image/gif, image/jpeg, image/png;
 321
 322         # cgo, delayed as long as possible.
 323         # If you add a dependency on CGO, you must add the package
 324         # to cgoPackages in cmd/dist/test.go as well.
 325         RUNTIME
 326         < C
 327         < runtime/cgo
 328         < CGO
 329         < runtime/msan, runtime/asan;
 330
 331         # runtime/race
 332         NONE < runtime/race/internal/amd64v1;
 333         NONE < runtime/race/internal/amd64v3;
 334         CGO, runtime/race/internal/amd64v1, runtime/race/internal/amd64v3 < runtime/race;
 335
 336         # Bulk of the standard library must not use cgo.
 337         # The prohibition stops at net and os/user.
 338         C !< fmt, go/types, CRYPTO-MATH, log/slog;
 339
 340         CGO, OS
 341         < plugin;
 342
 343         CGO, FMT
 344         < os/user
 345         < archive/tar;
 346
 347         sync
 348         < internal/singleflight;
 349
 350         os
 351         < golang.org/x/net/dns/dnsmessage,
 352           golang.org/x/net/lif,
 353           golang.org/x/net/route;
 354
 355         os, runtime, strconv, sync, unsafe,
 356         internal/godebug
 357         < internal/intern;
 358
 359         internal/bytealg, internal/intern, internal/itoa, math/bits, sort, strconv
 360         < net/netip;
 361
 362         # net is unavoidable when doing any networking,
 363         # so large dependencies must be kept out.
 364         # This is a long-looking list but most of these
 365         # are small with few dependencies.
 366         CGO,
 367         golang.org/x/net/dns/dnsmessage,
 368         golang.org/x/net/lif,
 369         golang.org/x/net/route,
 370         internal/godebug,
 371         internal/nettrace,
 372         internal/poll,
 373         internal/singleflight,
 374         internal/race,
 375         net/netip,
 376         os
 377         < net;
 378
 379         fmt, unicode !< net;
 380         math/rand !< net; # net uses runtime instead
 381
 382         # NET is net plus net-helper packages.
 383         FMT, net
 384         < net/textproto;
 385
 386         mime, net/textproto, net/url
 387         < NET;
 388
 389         # logging - most packages should not import; http and up is allowed
 390         FMT, log/internal
 391         < log;
 392
 393         log, log/slog !< crypto/tls, database/sql, go/importer, testing;
 394
 395         FMT, log, net
 396         < log/syslog;
 397
 398         RUNTIME
 399         < log/slog/internal, log/slog/internal/buffer;
 400
 401         FMT,
 402         encoding, encoding/json,
 403         log, log/internal,
 404         log/slog/internal, log/slog/internal/buffer,
 405         slices
 406         < log/slog
 407         < log/slog/internal/slogtest, log/slog/internal/benchmarks;
 408
 409         NET, log
 410         < net/mail;
 411
 412         NONE < crypto/internal/boring/sig, crypto/internal/boring/syso;
 413         sync/atomic < crypto/internal/boring/bcache, crypto/internal/boring/fipstls;
 414         crypto/internal/boring/sig, crypto/internal/boring/fipstls < crypto/tls/fipsonly;
 415
 416         # CRYPTO is core crypto algorithms - no cgo, fmt, net.
 417         # Unfortunately, stuck with reflect via encoding/binary.
 418         crypto/internal/boring/sig,
 419         crypto/internal/boring/syso,
 420         encoding/binary,
 421         golang.org/x/sys/cpu,
 422         hash, embed
 423         < crypto
 424         < crypto/subtle
 425         < crypto/internal/alias
 426         < crypto/cipher;
 427
 428         crypto/cipher,
 429         crypto/internal/boring/bcache
 430         < crypto/internal/boring
 431         < crypto/boring;
 432
 433         crypto/internal/alias
 434         < crypto/internal/randutil
 435         < crypto/internal/nistec/fiat
 436         < crypto/internal/nistec
 437         < crypto/internal/edwards25519/field
 438         < crypto/internal/edwards25519;
 439
 440         crypto/boring
 441         < crypto/aes, crypto/des, crypto/hmac, crypto/md5, crypto/rc4,
 442           crypto/sha1, crypto/sha256, crypto/sha512;
 443
 444         crypto/boring, crypto/internal/edwards25519/field
 445         < crypto/ecdh;
 446
 447         crypto/aes,
 448         crypto/des,
 449         crypto/ecdh,
 450         crypto/hmac,
 451         crypto/internal/edwards25519,
 452         crypto/md5,
 453         crypto/rc4,
 454         crypto/sha1,
 455         crypto/sha256,
 456         crypto/sha512
 457         < CRYPTO;
 458
 459         CGO, fmt, net !< CRYPTO;
 460
 461         # CRYPTO-MATH is core bignum-based crypto - no cgo, net; fmt now ok.
 462         CRYPTO, FMT, math/big
 463         < crypto/internal/boring/bbig
 464         < crypto/rand
 465         < crypto/ed25519
 466         < encoding/asn1
 467         < golang.org/x/crypto/cryptobyte/asn1
 468         < golang.org/x/crypto/cryptobyte
 469         < crypto/internal/bigmod
 470         < crypto/dsa, crypto/elliptic, crypto/rsa
 471         < crypto/ecdsa
 472         < CRYPTO-MATH;
 473
 474         CGO, net !< CRYPTO-MATH;
 475
 476         # TLS, Prince of Dependencies.
 477         CRYPTO-MATH, NET, container/list, encoding/hex, encoding/pem
 478         < golang.org/x/crypto/internal/alias
 479         < golang.org/x/crypto/internal/subtle
 480         < golang.org/x/crypto/chacha20
 481         < golang.org/x/crypto/internal/poly1305
 482         < golang.org/x/crypto/chacha20poly1305
 483         < golang.org/x/crypto/hkdf
 484         < crypto/x509/internal/macos
 485         < crypto/x509/pkix;
 486
 487         crypto/internal/boring/fipstls, crypto/x509/pkix
 488         < crypto/x509
 489         < crypto/tls;
 490
 491         # crypto-aware packages
 492
 493         DEBUG, go/build, go/types, text/scanner, crypto/md5
 494         < internal/pkgbits
 495         < go/internal/gcimporter, go/internal/gccgoimporter, go/internal/srcimporter
 496         < go/importer;
 497
 498         NET, crypto/rand, mime/quotedprintable
 499         < mime/multipart;
 500
 501         crypto/tls
 502         < net/smtp;
 503
 504         crypto/rand
 505         < hash/maphash; # for purego implementation
 506
 507         # HTTP, King of Dependencies.
 508
 509         FMT
 510         < golang.org/x/net/http2/hpack
 511         < net/http/internal, net/http/internal/ascii, net/http/internal/testcert;
 512
 513         FMT, NET, container/list, encoding/binary, log
 514         < golang.org/x/text/transform
 515         < golang.org/x/text/unicode/norm
 516         < golang.org/x/text/unicode/bidi
 517         < golang.org/x/text/secure/bidirule
 518         < golang.org/x/net/idna
 519         < golang.org/x/net/http/httpguts, golang.org/x/net/http/httpproxy;
 520
 521         NET, crypto/tls
 522         < net/http/httptrace;
 523
 524         compress/gzip,
 525         golang.org/x/net/http/httpguts,
 526         golang.org/x/net/http/httpproxy,
 527         golang.org/x/net/http2/hpack,
 528         net/http/internal,
 529         net/http/internal/ascii,
 530         net/http/internal/testcert,
 531         net/http/httptrace,
 532         mime/multipart,
 533         log
 534         < net/http;
 535
 536         # HTTP-aware packages
 537
 538         encoding/json, net/http
 539         < expvar;
 540
 541         net/http, net/http/internal/ascii
 542         < net/http/cookiejar, net/http/httputil;
 543
 544         net/http, flag
 545         < net/http/httptest;
 546
 547         net/http, regexp
 548         < net/http/cgi
 549         < net/http/fcgi;
 550
 551         # Profiling
 552         FMT, compress/gzip, encoding/binary, text/tabwriter
 553         < runtime/pprof;
 554
 555         OS, compress/gzip, internal/lazyregexp
 556         < internal/profile;
 557
 558         html, internal/profile, net/http, runtime/pprof, runtime/trace
 559         < net/http/pprof;
 560
 561         # RPC
 562         encoding/gob, encoding/json, go/token, html/template, net/http
 563         < net/rpc
 564         < net/rpc/jsonrpc;
 565
 566         # System Information
 567         bufio, bytes, internal/cpu, io, os, strings, sync
 568         < internal/sysinfo;
 569
 570         # Test-only
 571         log
 572         < testing/iotest
 573         < testing/fstest;
 574
 575         FMT, flag, math/rand
 576         < testing/quick;
 577
 578         FMT, DEBUG, flag, runtime/trace, internal/sysinfo, math/rand
 579         < testing;
 580
 581         log/slog, testing
 582         < testing/slogtest;
 583
 584         FMT, crypto/sha256, encoding/json, go/ast, go/parser, go/token,
 585         internal/godebug, math/rand, encoding/hex, crypto/sha256
 586         < internal/fuzz;
 587
 588         internal/fuzz, internal/testlog, runtime/pprof, regexp
 589         < testing/internal/testdeps;
 590
 591         OS, flag, testing, internal/cfg, internal/platform, internal/goroot
 592         < internal/testenv;
 593
 594         OS, encoding/base64
 595         < internal/obscuretestdata;
 596
 597         CGO, OS, fmt
 598         < internal/testpty;
 599
 600         NET, testing, math/rand
 601         < golang.org/x/net/nettest;
 602
 603         syscall
 604         < os/exec/internal/fdtest;
 605
 606         FMT, container/heap, math/rand
 607         < internal/trace;
 608
 609         FMT
 610         < internal/diff, internal/txtar;
 611
 612         FMT, crypto/md5, encoding/binary, regexp, sort, text/tabwriter, unsafe,
 613         internal/coverage, internal/coverage/uleb128
 614         < internal/coverage/cmerge,
 615           internal/coverage/pods,
 616           internal/coverage/slicereader,
 617           internal/coverage/slicewriter;
 618
 619         internal/coverage/slicereader, internal/coverage/slicewriter
 620         < internal/coverage/stringtab
 621         < internal/coverage/decodecounter, internal/coverage/decodemeta,
 622           internal/coverage/encodecounter, internal/coverage/encodemeta;
 623
 624         internal/coverage/cmerge
 625         < internal/coverage/cformat;
 626
 627         internal/coverage, crypto/sha256, FMT
 628         < cmd/internal/cov/covcmd;
 629
 630     encoding/json,
 631         runtime/debug,
 632         internal/coverage/calloc,
 633         internal/coverage/cformat,
 634         internal/coverage/decodecounter, internal/coverage/decodemeta,
 635         internal/coverage/encodecounter, internal/coverage/encodemeta,
 636         internal/coverage/pods
 637         < runtime/coverage;
 638 `
 639
 640 // listStdPkgs returns the same list of packages as "go list std".
 641 func listStdPkgs(goroot string) ([]string, error) {
 642         // Based on cmd/go's matchPackages function.
 643         var pkgs []string
 644
 645         src := filepath.Join(goroot, "src") + string(filepath.Separator)
 646         walkFn := func(path string, d fs.DirEntry, err error) error {
 647                 if err != nil || !d.IsDir() || path == src {
 648                         return nil
 649                 }
 650
 651                 base := filepath.Base(path)
 652                 if strings.HasPrefix(base, ".") || strings.HasPrefix(base, "_") || base == "testdata" {
 653                         return filepath.SkipDir
 654                 }
 655
 656                 name := filepath.ToSlash(path[len(src):])
 657                 if name == "builtin" || name == "cmd" {
 658                         return filepath.SkipDir
 659                 }
 660
 661                 pkgs = append(pkgs, strings.TrimPrefix(name, "vendor/"))
 662                 return nil
 663         }
 664         if err := filepath.WalkDir(src, walkFn); err != nil {
 665                 return nil, err
 666         }
 667         return pkgs, nil
 668 }
 669
 670 func TestDependencies(t *testing.T) {
 671         if !testenv.HasSrc() {
 672                 // Tests run in a limited file system and we do not
 673                 // provide access to every source file.
 674                 t.Skipf("skipping on %s/%s, missing full GOROOT", runtime.GOOS, runtime.GOARCH)
 675         }
 676
 677         ctxt := Default
 678         all, err := listStdPkgs(ctxt.GOROOT)
 679         if err != nil {
 680                 t.Fatal(err)
 681         }
 682         sort.Strings(all)
 683
 684         sawImport := map[string]map[string]bool{} // from package => to package => true
 685         policy := depsPolicy(t)
 686
 687         for _, pkg := range all {
 688                 imports, err := findImports(pkg)
 689                 if err != nil {
 690                         t.Error(err)
 691                         continue
 692                 }
 693                 if sawImport[pkg] == nil {
 694                         sawImport[pkg] = map[string]bool{}
 695                 }
 696                 var bad []string
 697                 for _, imp := range imports {
 698                         sawImport[pkg][imp] = true
 699                         if !policy.HasEdge(pkg, imp) {
 700                                 bad = append(bad, imp)
 701                         }
 702                 }
 703                 if bad != nil {
 704                         t.Errorf("unexpected dependency: %s imports %v", pkg, bad)
 705                 }
 706         }
 707 }
 708
 709 var buildIgnore = []byte("\n//go:build ignore")
 710
 711 func findImports(pkg string) ([]string, error) {
 712         vpkg := pkg
 713         if strings.HasPrefix(pkg, "golang.org") {
 714                 vpkg = "vendor/" + pkg
 715         }
 716         dir := filepath.Join(Default.GOROOT, "src", vpkg)
 717         files, err := os.ReadDir(dir)
 718         if err != nil {
 719                 return nil, err
 720         }
 721         var imports []string
 722         var haveImport = map[string]bool{}
 723         if pkg == "crypto/internal/boring" {
 724                 haveImport["C"] = true // kludge: prevent C from appearing in crypto/internal/boring imports
 725         }
 726         fset := token.NewFileSet()
 727         for _, file := range files {
 728                 name := file.Name()
 729                 if name == "slice_go14.go" || name == "slice_go18.go" {
 730                         // These files are for compiler bootstrap with older versions of Go and not built in the standard build.
 731                         continue
 732                 }
 733                 if !strings.HasSuffix(name, ".go") || strings.HasSuffix(name, "_test.go") {
 734                         continue
 735                 }
 736                 info := fileInfo{
 737                         name: filepath.Join(dir, name),
 738                         fset: fset,
 739                 }
 740                 f, err := os.Open(info.name)
 741                 if err != nil {
 742                         return nil, err
 743                 }
 744                 err = readGoInfo(f, &info)
 745                 f.Close()
 746                 if err != nil {
 747                         return nil, fmt.Errorf("reading %v: %v", name, err)
 748                 }
 749                 if info.parsed.Name.Name == "main" {
 750                         continue
 751                 }
 752                 if bytes.Contains(info.header, buildIgnore) {
 753                         continue
 754                 }
 755                 for _, imp := range info.imports {
 756                         path := imp.path
 757                         if !haveImport[path] {
 758                                 haveImport[path] = true
 759                                 imports = append(imports, path)
 760                         }
 761                 }
 762         }
 763         sort.Strings(imports)
 764         return imports, nil
 765 }
 766
 767 // depsPolicy returns a map m such that m[p][d] == true when p can import d.
 768 func depsPolicy(t *testing.T) *dag.Graph {
 769         g, err := dag.Parse(depsRules)
 770         if err != nil {
 771                 t.Fatal(err)
 772         }
 773         return g
 774 }
 775
 776 // TestStdlibLowercase tests that all standard library package names are
 777 // lowercase. See Issue 40065.
 778 func TestStdlibLowercase(t *testing.T) {
 779         if !testenv.HasSrc() {
 780                 t.Skipf("skipping on %s/%s, missing full GOROOT", runtime.GOOS, runtime.GOARCH)
 781         }
 782
 783         ctxt := Default
 784         all, err := listStdPkgs(ctxt.GOROOT)
 785         if err != nil {
 786                 t.Fatal(err)
 787         }
 788
 789         for _, pkgname := range all {
 790                 if strings.ToLower(pkgname) != pkgname {
 791                         t.Errorf("package %q should not use upper-case path", pkgname)
 792                 }
 793         }
 794 }
 795
 796 // TestFindImports tests that findImports works.  See #43249.
 797 func TestFindImports(t *testing.T) {
 798         imports, err := findImports("go/build")
 799         if err != nil {
 800                 t.Fatal(err)
 801         }
 802         t.Logf("go/build imports %q", imports)
 803         want := []string{"bytes", "os", "path/filepath", "strings"}
 804 wantLoop:
 805         for _, w := range want {
 806                 for _, imp := range imports {
 807                         if imp == w {
 808                                 continue wantLoop
 809                         }
 810                 }
 811                 t.Errorf("expected to find %q in import list", w)
 812         }
 813 }