test.go

Documentation: cmd/go/internal/load

     1  // Copyright 2018 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  package load
     6  
     7  import (
     8  	"bytes"
     9  	"context"
    10  	"errors"
    11  	"fmt"
    12  	"go/ast"
    13  	"go/build"
    14  	"go/doc"
    15  	"go/parser"
    16  	"go/token"
    17  	"internal/lazytemplate"
    18  	"path/filepath"
    19  	"slices"
    20  	"sort"
    21  	"strings"
    22  	"unicode"
    23  	"unicode/utf8"
    24  
    25  	"cmd/go/internal/cfg"
    26  	"cmd/go/internal/fsys"
    27  	"cmd/go/internal/str"
    28  	"cmd/go/internal/trace"
    29  )
    30  
    31  var TestMainDeps = []string{
    32  	// Dependencies for testmain.
    33  	"os",
    34  	"reflect",
    35  	"testing",
    36  	"testing/internal/testdeps",
    37  }
    38  
    39  type TestCover struct {
    40  	Mode  string
    41  	Local bool
    42  	Pkgs  []*Package
    43  	Paths []string
    44  	Vars  []coverInfo
    45  }
    46  
    47  // TestPackagesFor is like TestPackagesAndErrors but it returns
    48  // an error if the test packages or their dependencies have errors.
    49  // Only test packages without errors are returned.
    50  func TestPackagesFor(ctx context.Context, opts PackageOpts, p *Package, cover *TestCover) (pmain, ptest, pxtest *Package, err error) {
    51  	pmain, ptest, pxtest = TestPackagesAndErrors(ctx, nil, opts, p, cover)
    52  	for _, p1 := range []*Package{ptest, pxtest, pmain} {
    53  		if p1 == nil {
    54  			// pxtest may be nil
    55  			continue
    56  		}
    57  		if p1.Error != nil {
    58  			err = p1.Error
    59  			break
    60  		}
    61  		if p1.Incomplete {
    62  			ps := PackageList([]*Package{p1})
    63  			for _, p := range ps {
    64  				if p.Error != nil {
    65  					err = p.Error
    66  					break
    67  				}
    68  			}
    69  			break
    70  		}
    71  	}
    72  	if pmain.Error != nil || pmain.Incomplete {
    73  		pmain = nil
    74  	}
    75  	if ptest.Error != nil || ptest.Incomplete {
    76  		ptest = nil
    77  	}
    78  	if pxtest != nil && (pxtest.Error != nil || pxtest.Incomplete) {
    79  		pxtest = nil
    80  	}
    81  	return pmain, ptest, pxtest, err
    82  }
    83  
    84  // TestPackagesAndErrors returns three packages:
    85  //   - pmain, the package main corresponding to the test binary (running tests in ptest and pxtest).
    86  //   - ptest, the package p compiled with added "package p" test files.
    87  //   - pxtest, the result of compiling any "package p_test" (external) test files.
    88  //
    89  // If the package has no "package p_test" test files, pxtest will be nil.
    90  // If the non-test compilation of package p can be reused
    91  // (for example, if there are no "package p" test files and
    92  // package p need not be instrumented for coverage or any other reason),
    93  // then the returned ptest == p.
    94  //
    95  // If done is non-nil, TestPackagesAndErrors will finish filling out the returned
    96  // package structs in a goroutine and call done once finished. The members of the
    97  // returned packages should not be accessed until done is called.
    98  //
    99  // The caller is expected to have checked that len(p.TestGoFiles)+len(p.XTestGoFiles) > 0,
   100  // or else there's no point in any of this.
   101  func TestPackagesAndErrors(ctx context.Context, done func(), opts PackageOpts, p *Package, cover *TestCover) (pmain, ptest, pxtest *Package) {
   102  	ctx, span := trace.StartSpan(ctx, "load.TestPackagesAndErrors")
   103  	defer span.Done()
   104  
   105  	pre := newPreload()
   106  	defer pre.flush()
   107  	allImports := append([]string{}, p.TestImports...)
   108  	allImports = append(allImports, p.XTestImports...)
   109  	pre.preloadImports(ctx, opts, allImports, p.Internal.Build)
   110  
   111  	var ptestErr, pxtestErr *PackageError
   112  	var imports, ximports []*Package
   113  	var stk ImportStack
   114  	var testEmbed, xtestEmbed map[string][]string
   115  	var incomplete bool
   116  	stk.Push(p.ImportPath + " (test)")
   117  	rawTestImports := str.StringList(p.TestImports)
   118  	for i, path := range p.TestImports {
   119  		p1, err := loadImport(ctx, opts, pre, path, p.Dir, p, &stk, p.Internal.Build.TestImportPos[path], ResolveImport)
   120  		if err != nil && ptestErr == nil {
   121  			ptestErr = err
   122  			incomplete = true
   123  		}
   124  		if p1.Incomplete {
   125  			incomplete = true
   126  		}
   127  		p.TestImports[i] = p1.ImportPath
   128  		imports = append(imports, p1)
   129  	}
   130  	var err error
   131  	p.TestEmbedFiles, testEmbed, err = resolveEmbed(p.Dir, p.TestEmbedPatterns)
   132  	if err != nil {
   133  		ptestErr = &PackageError{
   134  			ImportStack: stk.Copy(),
   135  			Err:         err,
   136  		}
   137  		incomplete = true
   138  		embedErr := err.(*EmbedError)
   139  		ptestErr.setPos(p.Internal.Build.TestEmbedPatternPos[embedErr.Pattern])
   140  	}
   141  	stk.Pop()
   142  
   143  	stk.Push(p.ImportPath + "_test")
   144  	pxtestNeedsPtest := false
   145  	var pxtestIncomplete bool
   146  	rawXTestImports := str.StringList(p.XTestImports)
   147  	for i, path := range p.XTestImports {
   148  		p1, err := loadImport(ctx, opts, pre, path, p.Dir, p, &stk, p.Internal.Build.XTestImportPos[path], ResolveImport)
   149  		if err != nil && pxtestErr == nil {
   150  			pxtestErr = err
   151  		}
   152  		if p1.Incomplete {
   153  			pxtestIncomplete = true
   154  		}
   155  		if p1.ImportPath == p.ImportPath {
   156  			pxtestNeedsPtest = true
   157  		} else {
   158  			ximports = append(ximports, p1)
   159  		}
   160  		p.XTestImports[i] = p1.ImportPath
   161  	}
   162  	p.XTestEmbedFiles, xtestEmbed, err = resolveEmbed(p.Dir, p.XTestEmbedPatterns)
   163  	if err != nil && pxtestErr == nil {
   164  		pxtestErr = &PackageError{
   165  			ImportStack: stk.Copy(),
   166  			Err:         err,
   167  		}
   168  		embedErr := err.(*EmbedError)
   169  		pxtestErr.setPos(p.Internal.Build.XTestEmbedPatternPos[embedErr.Pattern])
   170  	}
   171  	pxtestIncomplete = pxtestIncomplete || pxtestErr != nil
   172  	stk.Pop()
   173  
   174  	// Test package.
   175  	if len(p.TestGoFiles) > 0 || p.Name == "main" || cover != nil && cover.Local {
   176  		ptest = new(Package)
   177  		*ptest = *p
   178  		ptest.Error = ptestErr
   179  		ptest.Incomplete = incomplete
   180  		ptest.ForTest = p.ImportPath
   181  		ptest.GoFiles = nil
   182  		ptest.GoFiles = append(ptest.GoFiles, p.GoFiles...)
   183  		ptest.GoFiles = append(ptest.GoFiles, p.TestGoFiles...)
   184  		ptest.Target = ""
   185  		// Note: The preparation of the vet config requires that common
   186  		// indexes in ptest.Imports and ptest.Internal.RawImports
   187  		// all line up (but RawImports can be shorter than the others).
   188  		// That is, for 0 ≤ i < len(RawImports),
   189  		// RawImports[i] is the import string in the program text, and
   190  		// Imports[i] is the expanded import string (vendoring applied or relative path expanded away).
   191  		// Any implicitly added imports appear in Imports and Internal.Imports
   192  		// but not RawImports (because they were not in the source code).
   193  		// We insert TestImports, imports, and rawTestImports at the start of
   194  		// these lists to preserve the alignment.
   195  		// Note that p.Internal.Imports may not be aligned with p.Imports/p.Internal.RawImports,
   196  		// but we insert at the beginning there too just for consistency.
   197  		ptest.Imports = str.StringList(p.TestImports, p.Imports)
   198  		ptest.Internal.Imports = append(imports, p.Internal.Imports...)
   199  		ptest.Internal.RawImports = str.StringList(rawTestImports, p.Internal.RawImports)
   200  		ptest.Internal.ForceLibrary = true
   201  		ptest.Internal.BuildInfo = nil
   202  		ptest.Internal.Build = new(build.Package)
   203  		*ptest.Internal.Build = *p.Internal.Build
   204  		m := map[string][]token.Position{}
   205  		for k, v := range p.Internal.Build.ImportPos {
   206  			m[k] = append(m[k], v...)
   207  		}
   208  		for k, v := range p.Internal.Build.TestImportPos {
   209  			m[k] = append(m[k], v...)
   210  		}
   211  		ptest.Internal.Build.ImportPos = m
   212  		if testEmbed == nil && len(p.Internal.Embed) > 0 {
   213  			testEmbed = map[string][]string{}
   214  		}
   215  		for k, v := range p.Internal.Embed {
   216  			testEmbed[k] = v
   217  		}
   218  		ptest.Internal.Embed = testEmbed
   219  		ptest.EmbedFiles = str.StringList(p.EmbedFiles, p.TestEmbedFiles)
   220  		ptest.Internal.OrigImportPath = p.Internal.OrigImportPath
   221  		ptest.Internal.PGOProfile = p.Internal.PGOProfile
   222  		ptest.Internal.Build.Directives = append(slices.Clip(p.Internal.Build.Directives), p.Internal.Build.TestDirectives...)
   223  	} else {
   224  		ptest = p
   225  	}
   226  
   227  	// External test package.
   228  	if len(p.XTestGoFiles) > 0 {
   229  		pxtest = &Package{
   230  			PackagePublic: PackagePublic{
   231  				Name:       p.Name + "_test",
   232  				ImportPath: p.ImportPath + "_test",
   233  				Root:       p.Root,
   234  				Dir:        p.Dir,
   235  				Goroot:     p.Goroot,
   236  				GoFiles:    p.XTestGoFiles,
   237  				Imports:    p.XTestImports,
   238  				ForTest:    p.ImportPath,
   239  				Module:     p.Module,
   240  				Error:      pxtestErr,
   241  				Incomplete: pxtestIncomplete,
   242  				EmbedFiles: p.XTestEmbedFiles,
   243  			},
   244  			Internal: PackageInternal{
   245  				LocalPrefix: p.Internal.LocalPrefix,
   246  				Build: &build.Package{
   247  					ImportPos:  p.Internal.Build.XTestImportPos,
   248  					Directives: p.Internal.Build.XTestDirectives,
   249  				},
   250  				Imports:    ximports,
   251  				RawImports: rawXTestImports,
   252  
   253  				Asmflags:       p.Internal.Asmflags,
   254  				Gcflags:        p.Internal.Gcflags,
   255  				Ldflags:        p.Internal.Ldflags,
   256  				Gccgoflags:     p.Internal.Gccgoflags,
   257  				Embed:          xtestEmbed,
   258  				OrigImportPath: p.Internal.OrigImportPath,
   259  				PGOProfile:     p.Internal.PGOProfile,
   260  			},
   261  		}
   262  		if pxtestNeedsPtest {
   263  			pxtest.Internal.Imports = append(pxtest.Internal.Imports, ptest)
   264  		}
   265  	}
   266  
   267  	// Arrange for testing.Testing to report true.
   268  	ldflags := append(p.Internal.Ldflags, "-X", "testing.testBinary=1")
   269  	gccgoflags := append(p.Internal.Gccgoflags, "-Wl,--defsym,testing.gccgoTestBinary=1")
   270  
   271  	// Build main package.
   272  	pmain = &Package{
   273  		PackagePublic: PackagePublic{
   274  			Name:       "main",
   275  			Dir:        p.Dir,
   276  			GoFiles:    []string{"_testmain.go"},
   277  			ImportPath: p.ImportPath + ".test",
   278  			Root:       p.Root,
   279  			Imports:    str.StringList(TestMainDeps),
   280  			Module:     p.Module,
   281  		},
   282  		Internal: PackageInternal{
   283  			Build:          &build.Package{Name: "main"},
   284  			BuildInfo:      p.Internal.BuildInfo,
   285  			Asmflags:       p.Internal.Asmflags,
   286  			Gcflags:        p.Internal.Gcflags,
   287  			Ldflags:        ldflags,
   288  			Gccgoflags:     gccgoflags,
   289  			OrigImportPath: p.Internal.OrigImportPath,
   290  			PGOProfile:     p.Internal.PGOProfile,
   291  		},
   292  	}
   293  
   294  	pb := p.Internal.Build
   295  	pmain.DefaultGODEBUG = defaultGODEBUG(pmain, pb.Directives, pb.TestDirectives, pb.XTestDirectives)
   296  
   297  	// The generated main also imports testing, regexp, and os.
   298  	// Also the linker introduces implicit dependencies reported by LinkerDeps.
   299  	stk.Push("testmain")
   300  	deps := TestMainDeps // cap==len, so safe for append
   301  	if cover != nil && cfg.Experiment.CoverageRedesign {
   302  		deps = append(deps, "internal/coverage/cfile")
   303  	}
   304  	ldDeps, err := LinkerDeps(p)
   305  	if err != nil && pmain.Error == nil {
   306  		pmain.Error = &PackageError{Err: err}
   307  	}
   308  	for _, d := range ldDeps {
   309  		deps = append(deps, d)
   310  	}
   311  	for _, dep := range deps {
   312  		if dep == ptest.ImportPath {
   313  			pmain.Internal.Imports = append(pmain.Internal.Imports, ptest)
   314  		} else {
   315  			p1, err := loadImport(ctx, opts, pre, dep, "", nil, &stk, nil, 0)
   316  			if err != nil && pmain.Error == nil {
   317  				pmain.Error = err
   318  				pmain.Incomplete = true
   319  			}
   320  			pmain.Internal.Imports = append(pmain.Internal.Imports, p1)
   321  		}
   322  	}
   323  	stk.Pop()
   324  
   325  	parallelizablePart := func() {
   326  		if cover != nil && cover.Pkgs != nil && !cfg.Experiment.CoverageRedesign {
   327  			// Add imports, but avoid duplicates.
   328  			seen := map[*Package]bool{p: true, ptest: true}
   329  			for _, p1 := range pmain.Internal.Imports {
   330  				seen[p1] = true
   331  			}
   332  			for _, p1 := range cover.Pkgs {
   333  				if seen[p1] {
   334  					// Don't add duplicate imports.
   335  					continue
   336  				}
   337  				seen[p1] = true
   338  				pmain.Internal.Imports = append(pmain.Internal.Imports, p1)
   339  			}
   340  		}
   341  
   342  		allTestImports := make([]*Package, 0, len(pmain.Internal.Imports)+len(imports)+len(ximports))
   343  		allTestImports = append(allTestImports, pmain.Internal.Imports...)
   344  		allTestImports = append(allTestImports, imports...)
   345  		allTestImports = append(allTestImports, ximports...)
   346  		setToolFlags(allTestImports...)
   347  
   348  		// Do initial scan for metadata needed for writing _testmain.go
   349  		// Use that metadata to update the list of imports for package main.
   350  		// The list of imports is used by recompileForTest and by the loop
   351  		// afterward that gathers t.Cover information.
   352  		t, err := loadTestFuncs(p)
   353  		if err != nil && pmain.Error == nil {
   354  			pmain.setLoadPackageDataError(err, p.ImportPath, &stk, nil)
   355  		}
   356  		t.Cover = cover
   357  		if len(ptest.GoFiles)+len(ptest.CgoFiles) > 0 {
   358  			pmain.Internal.Imports = append(pmain.Internal.Imports, ptest)
   359  			pmain.Imports = append(pmain.Imports, ptest.ImportPath)
   360  			t.ImportTest = true
   361  		}
   362  		if pxtest != nil {
   363  			pmain.Internal.Imports = append(pmain.Internal.Imports, pxtest)
   364  			pmain.Imports = append(pmain.Imports, pxtest.ImportPath)
   365  			t.ImportXtest = true
   366  		}
   367  
   368  		// Sort and dedup pmain.Imports.
   369  		// Only matters for go list -test output.
   370  		sort.Strings(pmain.Imports)
   371  		w := 0
   372  		for _, path := range pmain.Imports {
   373  			if w == 0 || path != pmain.Imports[w-1] {
   374  				pmain.Imports[w] = path
   375  				w++
   376  			}
   377  		}
   378  		pmain.Imports = pmain.Imports[:w]
   379  		pmain.Internal.RawImports = str.StringList(pmain.Imports)
   380  
   381  		// Replace pmain's transitive dependencies with test copies, as necessary.
   382  		cycleErr := recompileForTest(pmain, p, ptest, pxtest)
   383  		if cycleErr != nil {
   384  			ptest.Error = cycleErr
   385  			ptest.Incomplete = true
   386  		}
   387  
   388  		if cover != nil {
   389  			if cfg.Experiment.CoverageRedesign {
   390  				// Here ptest needs to inherit the proper coverage mode (since
   391  				// it contains p's Go files), whereas pmain contains only
   392  				// test harness code (don't want to instrument it, and
   393  				// we don't want coverage hooks in the pkg init).
   394  				ptest.Internal.Cover.Mode = p.Internal.Cover.Mode
   395  				pmain.Internal.Cover.Mode = "testmain"
   396  			}
   397  			// Should we apply coverage analysis locally, only for this
   398  			// package and only for this test? Yes, if -cover is on but
   399  			// -coverpkg has not specified a list of packages for global
   400  			// coverage.
   401  			if cover.Local {
   402  				ptest.Internal.Cover.Mode = cover.Mode
   403  
   404  				if !cfg.Experiment.CoverageRedesign {
   405  					var coverFiles []string
   406  					coverFiles = append(coverFiles, ptest.GoFiles...)
   407  					coverFiles = append(coverFiles, ptest.CgoFiles...)
   408  					ptest.Internal.CoverVars = DeclareCoverVars(ptest, coverFiles...)
   409  				}
   410  			}
   411  
   412  			if !cfg.Experiment.CoverageRedesign {
   413  				for _, cp := range pmain.Internal.Imports {
   414  					if len(cp.Internal.CoverVars) > 0 {
   415  						t.Cover.Vars = append(t.Cover.Vars, coverInfo{cp, cp.Internal.CoverVars})
   416  					}
   417  				}
   418  			}
   419  		}
   420  
   421  		data, err := formatTestmain(t)
   422  		if err != nil && pmain.Error == nil {
   423  			pmain.Error = &PackageError{Err: err}
   424  			pmain.Incomplete = true
   425  		}
   426  		// Set TestmainGo even if it is empty: the presence of a TestmainGo
   427  		// indicates that this package is, in fact, a test main.
   428  		pmain.Internal.TestmainGo = &data
   429  	}
   430  
   431  	if done != nil {
   432  		go func() {
   433  			parallelizablePart()
   434  			done()
   435  		}()
   436  	} else {
   437  		parallelizablePart()
   438  	}
   439  
   440  	return pmain, ptest, pxtest
   441  }
   442  
   443  // recompileForTest copies and replaces certain packages in pmain's dependency
   444  // graph. This is necessary for two reasons. First, if ptest is different than
   445  // preal, packages that import the package under test should get ptest instead
   446  // of preal. This is particularly important if pxtest depends on functionality
   447  // exposed in test sources in ptest. Second, if there is a main package
   448  // (other than pmain) anywhere, we need to set p.Internal.ForceLibrary and
   449  // clear p.Internal.BuildInfo in the test copy to prevent link conflicts.
   450  // This may happen if both -coverpkg and the command line patterns include
   451  // multiple main packages.
   452  func recompileForTest(pmain, preal, ptest, pxtest *Package) *PackageError {
   453  	// The "test copy" of preal is ptest.
   454  	// For each package that depends on preal, make a "test copy"
   455  	// that depends on ptest. And so on, up the dependency tree.
   456  	testCopy := map[*Package]*Package{preal: ptest}
   457  	for _, p := range PackageList([]*Package{pmain}) {
   458  		if p == preal {
   459  			continue
   460  		}
   461  		// Copy on write.
   462  		didSplit := p == pmain || p == pxtest || p == ptest
   463  		split := func() {
   464  			if didSplit {
   465  				return
   466  			}
   467  			didSplit = true
   468  			if testCopy[p] != nil {
   469  				panic("recompileForTest loop")
   470  			}
   471  			p1 := new(Package)
   472  			testCopy[p] = p1
   473  			*p1 = *p
   474  			p1.ForTest = preal.ImportPath
   475  			p1.Internal.Imports = make([]*Package, len(p.Internal.Imports))
   476  			copy(p1.Internal.Imports, p.Internal.Imports)
   477  			p1.Imports = make([]string, len(p.Imports))
   478  			copy(p1.Imports, p.Imports)
   479  			p = p1
   480  			p.Target = ""
   481  			p.Internal.BuildInfo = nil
   482  			p.Internal.ForceLibrary = true
   483  			p.Internal.PGOProfile = preal.Internal.PGOProfile
   484  		}
   485  
   486  		// Update p.Internal.Imports to use test copies.
   487  		for i, imp := range p.Internal.Imports {
   488  			if p1 := testCopy[imp]; p1 != nil && p1 != imp {
   489  				split()
   490  
   491  				// If the test dependencies cause a cycle with pmain, this is
   492  				// where it is introduced.
   493  				// (There are no cycles in the graph until this assignment occurs.)
   494  				p.Internal.Imports[i] = p1
   495  			}
   496  		}
   497  
   498  		// Force main packages the test imports to be built as libraries.
   499  		// Normal imports of main packages are forbidden by the package loader,
   500  		// but this can still happen if -coverpkg patterns include main packages:
   501  		// covered packages are imported by pmain. Linking multiple packages
   502  		// compiled with '-p main' causes duplicate symbol errors.
   503  		// See golang.org/issue/30907, golang.org/issue/34114.
   504  		if p.Name == "main" && p != pmain && p != ptest {
   505  			split()
   506  		}
   507  		// Split and attach PGO information to test dependencies if preal
   508  		// is built with PGO.
   509  		if preal.Internal.PGOProfile != "" && p.Internal.PGOProfile == "" {
   510  			split()
   511  		}
   512  	}
   513  
   514  	// Do search to find cycle.
   515  	// importerOf maps each import path to its importer nearest to p.
   516  	importerOf := map[*Package]*Package{}
   517  	for _, p := range ptest.Internal.Imports {
   518  		importerOf[p] = nil
   519  	}
   520  
   521  	// q is a breadth-first queue of packages to search for target.
   522  	// Every package added to q has a corresponding entry in pathTo.
   523  	//
   524  	// We search breadth-first for two reasons:
   525  	//
   526  	// 	1. We want to report the shortest cycle.
   527  	//
   528  	// 	2. If p contains multiple cycles, the first cycle we encounter might not
   529  	// 	   contain target. To ensure termination, we have to break all cycles
   530  	// 	   other than the first.
   531  	q := slices.Clip(ptest.Internal.Imports)
   532  	for len(q) > 0 {
   533  		p := q[0]
   534  		q = q[1:]
   535  		if p == ptest {
   536  			// The stack is supposed to be in the order x imports y imports z.
   537  			// We collect in the reverse order: z is imported by y is imported
   538  			// by x, and then we reverse it.
   539  			var stk []string
   540  			for p != nil {
   541  				stk = append(stk, p.ImportPath)
   542  				p = importerOf[p]
   543  			}
   544  			// complete the cycle: we set importer[p] = nil to break the cycle
   545  			// in importerOf, it's an implicit importerOf[p] == pTest. Add it
   546  			// back here since we reached nil in the loop above to demonstrate
   547  			// the cycle as (for example) package p imports package q imports package r
   548  			// imports package p.
   549  			stk = append(stk, ptest.ImportPath)
   550  			slices.Reverse(stk)
   551  
   552  			return &PackageError{
   553  				ImportStack:   stk,
   554  				Err:           errors.New("import cycle not allowed in test"),
   555  				IsImportCycle: true,
   556  			}
   557  		}
   558  		for _, dep := range p.Internal.Imports {
   559  			if _, ok := importerOf[dep]; !ok {
   560  				importerOf[dep] = p
   561  				q = append(q, dep)
   562  			}
   563  		}
   564  	}
   565  
   566  	return nil
   567  }
   568  
   569  // isTestFunc tells whether fn has the type of a testing function. arg
   570  // specifies the parameter type we look for: B, F, M or T.
   571  func isTestFunc(fn *ast.FuncDecl, arg string) bool {
   572  	if fn.Type.Results != nil && len(fn.Type.Results.List) > 0 ||
   573  		fn.Type.Params.List == nil ||
   574  		len(fn.Type.Params.List) != 1 ||
   575  		len(fn.Type.Params.List[0].Names) > 1 {
   576  		return false
   577  	}
   578  	ptr, ok := fn.Type.Params.List[0].Type.(*ast.StarExpr)
   579  	if !ok {
   580  		return false
   581  	}
   582  	// We can't easily check that the type is *testing.M
   583  	// because we don't know how testing has been imported,
   584  	// but at least check that it's *M or *something.M.
   585  	// Same applies for B, F and T.
   586  	if name, ok := ptr.X.(*ast.Ident); ok && name.Name == arg {
   587  		return true
   588  	}
   589  	if sel, ok := ptr.X.(*ast.SelectorExpr); ok && sel.Sel.Name == arg {
   590  		return true
   591  	}
   592  	return false
   593  }
   594  
   595  // isTest tells whether name looks like a test (or benchmark, according to prefix).
   596  // It is a Test (say) if there is a character after Test that is not a lower-case letter.
   597  // We don't want TesticularCancer.
   598  func isTest(name, prefix string) bool {
   599  	if !strings.HasPrefix(name, prefix) {
   600  		return false
   601  	}
   602  	if len(name) == len(prefix) { // "Test" is ok
   603  		return true
   604  	}
   605  	rune, _ := utf8.DecodeRuneInString(name[len(prefix):])
   606  	return !unicode.IsLower(rune)
   607  }
   608  
   609  type coverInfo struct {
   610  	Package *Package
   611  	Vars    map[string]*CoverVar
   612  }
   613  
   614  // loadTestFuncs returns the testFuncs describing the tests that will be run.
   615  // The returned testFuncs is always non-nil, even if an error occurred while
   616  // processing test files.
   617  func loadTestFuncs(ptest *Package) (*testFuncs, error) {
   618  	t := &testFuncs{
   619  		Package: ptest,
   620  	}
   621  	var err error
   622  	for _, file := range ptest.TestGoFiles {
   623  		if lerr := t.load(filepath.Join(ptest.Dir, file), "_test", &t.ImportTest, &t.NeedTest); lerr != nil && err == nil {
   624  			err = lerr
   625  		}
   626  	}
   627  	for _, file := range ptest.XTestGoFiles {
   628  		if lerr := t.load(filepath.Join(ptest.Dir, file), "_xtest", &t.ImportXtest, &t.NeedXtest); lerr != nil && err == nil {
   629  			err = lerr
   630  		}
   631  	}
   632  	return t, err
   633  }
   634  
   635  // formatTestmain returns the content of the _testmain.go file for t.
   636  func formatTestmain(t *testFuncs) ([]byte, error) {
   637  	var buf bytes.Buffer
   638  	tmpl := testmainTmpl
   639  	if cfg.Experiment.CoverageRedesign {
   640  		tmpl = testmainTmplNewCoverage
   641  	}
   642  	if err := tmpl.Execute(&buf, t); err != nil {
   643  		return nil, err
   644  	}
   645  	return buf.Bytes(), nil
   646  }
   647  
   648  type testFuncs struct {
   649  	Tests       []testFunc
   650  	Benchmarks  []testFunc
   651  	FuzzTargets []testFunc
   652  	Examples    []testFunc
   653  	TestMain    *testFunc
   654  	Package     *Package
   655  	ImportTest  bool
   656  	NeedTest    bool
   657  	ImportXtest bool
   658  	NeedXtest   bool
   659  	Cover       *TestCover
   660  }
   661  
   662  // ImportPath returns the import path of the package being tested, if it is within GOPATH.
   663  // This is printed by the testing package when running benchmarks.
   664  func (t *testFuncs) ImportPath() string {
   665  	pkg := t.Package.ImportPath
   666  	if strings.HasPrefix(pkg, "_/") {
   667  		return ""
   668  	}
   669  	if pkg == "command-line-arguments" {
   670  		return ""
   671  	}
   672  	return pkg
   673  }
   674  
   675  // Covered returns a string describing which packages are being tested for coverage.
   676  // If the covered package is the same as the tested package, it returns the empty string.
   677  // Otherwise it is a comma-separated human-readable list of packages beginning with
   678  // " in", ready for use in the coverage message.
   679  func (t *testFuncs) Covered() string {
   680  	if t.Cover == nil || t.Cover.Paths == nil {
   681  		return ""
   682  	}
   683  	return " in " + strings.Join(t.Cover.Paths, ", ")
   684  }
   685  
   686  func (t *testFuncs) CoverSelectedPackages() string {
   687  	if t.Cover == nil || t.Cover.Paths == nil {
   688  		return `[]string{"` + t.Package.ImportPath + `"}`
   689  	}
   690  	var sb strings.Builder
   691  	fmt.Fprintf(&sb, "[]string{")
   692  	for k, p := range t.Cover.Pkgs {
   693  		if k != 0 {
   694  			sb.WriteString(", ")
   695  		}
   696  		fmt.Fprintf(&sb, `"%s"`, p.ImportPath)
   697  	}
   698  	sb.WriteString("}")
   699  	return sb.String()
   700  }
   701  
   702  // Tested returns the name of the package being tested.
   703  func (t *testFuncs) Tested() string {
   704  	return t.Package.Name
   705  }
   706  
   707  type testFunc struct {
   708  	Package   string // imported package name (_test or _xtest)
   709  	Name      string // function name
   710  	Output    string // output, for examples
   711  	Unordered bool   // output is allowed to be unordered.
   712  }
   713  
   714  var testFileSet = token.NewFileSet()
   715  
   716  func (t *testFuncs) load(filename, pkg string, doImport, seen *bool) error {
   717  	// Pass in the overlaid source if we have an overlay for this file.
   718  	src, err := fsys.Open(filename)
   719  	if err != nil {
   720  		return err
   721  	}
   722  	defer src.Close()
   723  	f, err := parser.ParseFile(testFileSet, filename, src, parser.ParseComments|parser.SkipObjectResolution)
   724  	if err != nil {
   725  		return err
   726  	}
   727  	for _, d := range f.Decls {
   728  		n, ok := d.(*ast.FuncDecl)
   729  		if !ok {
   730  			continue
   731  		}
   732  		if n.Recv != nil {
   733  			continue
   734  		}
   735  		name := n.Name.String()
   736  		switch {
   737  		case name == "TestMain":
   738  			if isTestFunc(n, "T") {
   739  				t.Tests = append(t.Tests, testFunc{pkg, name, "", false})
   740  				*doImport, *seen = true, true
   741  				continue
   742  			}
   743  			err := checkTestFunc(n, "M")
   744  			if err != nil {
   745  				return err
   746  			}
   747  			if t.TestMain != nil {
   748  				return errors.New("multiple definitions of TestMain")
   749  			}
   750  			t.TestMain = &testFunc{pkg, name, "", false}
   751  			*doImport, *seen = true, true
   752  		case isTest(name, "Test"):
   753  			err := checkTestFunc(n, "T")
   754  			if err != nil {
   755  				return err
   756  			}
   757  			t.Tests = append(t.Tests, testFunc{pkg, name, "", false})
   758  			*doImport, *seen = true, true
   759  		case isTest(name, "Benchmark"):
   760  			err := checkTestFunc(n, "B")
   761  			if err != nil {
   762  				return err
   763  			}
   764  			t.Benchmarks = append(t.Benchmarks, testFunc{pkg, name, "", false})
   765  			*doImport, *seen = true, true
   766  		case isTest(name, "Fuzz"):
   767  			err := checkTestFunc(n, "F")
   768  			if err != nil {
   769  				return err
   770  			}
   771  			t.FuzzTargets = append(t.FuzzTargets, testFunc{pkg, name, "", false})
   772  			*doImport, *seen = true, true
   773  		}
   774  	}
   775  	ex := doc.Examples(f)
   776  	sort.Slice(ex, func(i, j int) bool { return ex[i].Order < ex[j].Order })
   777  	for _, e := range ex {
   778  		*doImport = true // import test file whether executed or not
   779  		if e.Output == "" && !e.EmptyOutput {
   780  			// Don't run examples with no output.
   781  			continue
   782  		}
   783  		t.Examples = append(t.Examples, testFunc{pkg, "Example" + e.Name, e.Output, e.Unordered})
   784  		*seen = true
   785  	}
   786  	return nil
   787  }
   788  
   789  func checkTestFunc(fn *ast.FuncDecl, arg string) error {
   790  	var why string
   791  	if !isTestFunc(fn, arg) {
   792  		why = fmt.Sprintf("must be: func %s(%s *testing.%s)", fn.Name.String(), strings.ToLower(arg), arg)
   793  	}
   794  	if fn.Type.TypeParams.NumFields() > 0 {
   795  		why = "test functions cannot have type parameters"
   796  	}
   797  	if why != "" {
   798  		pos := testFileSet.Position(fn.Pos())
   799  		return fmt.Errorf("%s: wrong signature for %s, %s", pos, fn.Name.String(), why)
   800  	}
   801  	return nil
   802  }
   803  
   804  var testmainTmpl = lazytemplate.New("main", `
   805  // Code generated by 'go test'. DO NOT EDIT.
   806  
   807  package main
   808  
   809  import (
   810  	"os"
   811  {{if .TestMain}}
   812  	"reflect"
   813  {{end}}
   814  	"testing"
   815  	"testing/internal/testdeps"
   816  
   817  {{if .ImportTest}}
   818  	{{if .NeedTest}}_test{{else}}_{{end}} {{.Package.ImportPath | printf "%q"}}
   819  {{end}}
   820  {{if .ImportXtest}}
   821  	{{if .NeedXtest}}_xtest{{else}}_{{end}} {{.Package.ImportPath | printf "%s_test" | printf "%q"}}
   822  {{end}}
   823  {{if .Cover}}
   824  {{range $i, $p := .Cover.Vars}}
   825  	_cover{{$i}} {{$p.Package.ImportPath | printf "%q"}}
   826  {{end}}
   827  {{end}}
   828  )
   829  
   830  var tests = []testing.InternalTest{
   831  {{range .Tests}}
   832  	{"{{.Name}}", {{.Package}}.{{.Name}}},
   833  {{end}}
   834  }
   835  
   836  var benchmarks = []testing.InternalBenchmark{
   837  {{range .Benchmarks}}
   838  	{"{{.Name}}", {{.Package}}.{{.Name}}},
   839  {{end}}
   840  }
   841  
   842  var fuzzTargets = []testing.InternalFuzzTarget{
   843  {{range .FuzzTargets}}
   844  	{"{{.Name}}", {{.Package}}.{{.Name}}},
   845  {{end}}
   846  }
   847  
   848  var examples = []testing.InternalExample{
   849  {{range .Examples}}
   850  	{"{{.Name}}", {{.Package}}.{{.Name}}, {{.Output | printf "%q"}}, {{.Unordered}}},
   851  {{end}}
   852  }
   853  
   854  func init() {
   855  	testdeps.ImportPath = {{.ImportPath | printf "%q"}}
   856  }
   857  
   858  {{if .Cover}}
   859  
   860  // Only updated by init functions, so no need for atomicity.
   861  var (
   862  	coverCounters = make(map[string][]uint32)
   863  	coverBlocks = make(map[string][]testing.CoverBlock)
   864  )
   865  
   866  func init() {
   867  	{{range $i, $p := .Cover.Vars}}
   868  	{{range $file, $cover := $p.Vars}}
   869  	coverRegisterFile({{printf "%q" $cover.File}}, _cover{{$i}}.{{$cover.Var}}.Count[:], _cover{{$i}}.{{$cover.Var}}.Pos[:], _cover{{$i}}.{{$cover.Var}}.NumStmt[:])
   870  	{{end}}
   871  	{{end}}
   872  }
   873  
   874  func coverRegisterFile(fileName string, counter []uint32, pos []uint32, numStmts []uint16) {
   875  	if 3*len(counter) != len(pos) || len(counter) != len(numStmts) {
   876  		panic("coverage: mismatched sizes")
   877  	}
   878  	if coverCounters[fileName] != nil {
   879  		// Already registered.
   880  		return
   881  	}
   882  	coverCounters[fileName] = counter
   883  	block := make([]testing.CoverBlock, len(counter))
   884  	for i := range counter {
   885  		block[i] = testing.CoverBlock{
   886  			Line0: pos[3*i+0],
   887  			Col0: uint16(pos[3*i+2]),
   888  			Line1: pos[3*i+1],
   889  			Col1: uint16(pos[3*i+2]>>16),
   890  			Stmts: numStmts[i],
   891  		}
   892  	}
   893  	coverBlocks[fileName] = block
   894  }
   895  {{end}}
   896  
   897  func main() {
   898  {{if .Cover}}
   899  	testing.RegisterCover(testing.Cover{
   900  		Mode: {{printf "%q" .Cover.Mode}},
   901  		Counters: coverCounters,
   902  		Blocks: coverBlocks,
   903  		CoveredPackages: {{printf "%q" .Covered}},
   904  	})
   905  {{end}}
   906  	m := testing.MainStart(testdeps.TestDeps{}, tests, benchmarks, fuzzTargets, examples)
   907  {{with .TestMain}}
   908  	{{.Package}}.{{.Name}}(m)
   909  	os.Exit(int(reflect.ValueOf(m).Elem().FieldByName("exitCode").Int()))
   910  {{else}}
   911  	os.Exit(m.Run())
   912  {{end}}
   913  }
   914  
   915  `)
   916  
   917  var testmainTmplNewCoverage = lazytemplate.New("main", `
   918  // Code generated by 'go test'. DO NOT EDIT.
   919  
   920  package main
   921  
   922  import (
   923  	"os"
   924  {{if .TestMain}}
   925  	"reflect"
   926  {{end}}
   927  	"testing"
   928  	"testing/internal/testdeps"
   929  {{if .Cover}}
   930  	"internal/coverage/cfile"
   931  {{end}}
   932  
   933  {{if .ImportTest}}
   934  	{{if .NeedTest}}_test{{else}}_{{end}} {{.Package.ImportPath | printf "%q"}}
   935  {{end}}
   936  {{if .ImportXtest}}
   937  	{{if .NeedXtest}}_xtest{{else}}_{{end}} {{.Package.ImportPath | printf "%s_test" | printf "%q"}}
   938  {{end}}
   939  )
   940  
   941  var tests = []testing.InternalTest{
   942  {{range .Tests}}
   943  	{"{{.Name}}", {{.Package}}.{{.Name}}},
   944  {{end}}
   945  }
   946  
   947  var benchmarks = []testing.InternalBenchmark{
   948  {{range .Benchmarks}}
   949  	{"{{.Name}}", {{.Package}}.{{.Name}}},
   950  {{end}}
   951  }
   952  
   953  var fuzzTargets = []testing.InternalFuzzTarget{
   954  {{range .FuzzTargets}}
   955  	{"{{.Name}}", {{.Package}}.{{.Name}}},
   956  {{end}}
   957  }
   958  
   959  var examples = []testing.InternalExample{
   960  {{range .Examples}}
   961  	{"{{.Name}}", {{.Package}}.{{.Name}}, {{.Output | printf "%q"}}, {{.Unordered}}},
   962  {{end}}
   963  }
   964  
   965  func init() {
   966  {{if .Cover}}
   967  	testdeps.CoverMode = {{printf "%q" .Cover.Mode}}
   968  	testdeps.Covered = {{printf "%q" .Covered}}
   969  	testdeps.CoverSelectedPackages = {{printf "%s" .CoverSelectedPackages}}
   970  	testdeps.CoverSnapshotFunc = cfile.Snapshot
   971  	testdeps.CoverProcessTestDirFunc = cfile.ProcessCoverTestDir
   972  	testdeps.CoverMarkProfileEmittedFunc = cfile.MarkProfileEmitted
   973  
   974  {{end}}
   975  	testdeps.ImportPath = {{.ImportPath | printf "%q"}}
   976  }
   977  
   978  func main() {
   979  	m := testing.MainStart(testdeps.TestDeps{}, tests, benchmarks, fuzzTargets, examples)
   980  {{with .TestMain}}
   981  	{{.Package}}.{{.Name}}(m)
   982  	os.Exit(int(reflect.ValueOf(m).Elem().FieldByName("exitCode").Int()))
   983  {{else}}
   984  	os.Exit(m.Run())
   985  {{end}}
   986  }
   987  
   988  `)
   989
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