github.com/gernest/nezuko@v0.1.2/internal/load/test.go

// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package load

import (
	"bytes"
	"errors"
	"fmt"
	"go/ast"
	"go/doc"
	"go/parser"
	"go/token"
	"path/filepath"
	"sort"
	"strings"
	"text/template"
	"unicode"
	"unicode/utf8"

	"github.com/gernest/nezuko/internal/base"
	"github.com/gernest/nezuko/internal/str"
)

var TestMainDeps = []string{
	// Dependencies for testmain.
	"os",
	"testing",
	"testing/internal/testdeps",
}

type TestCover struct {
	Mode     string
	Local    bool
	Pkgs     []*Package
	Paths    []string
	Vars     []coverInfo
	DeclVars func(*Package, ...string) map[string]*CoverVar
}

func testImportStack(top string, p *Package, target string) []string {
	stk := []string{top, p.ImportPath}
Search:
	for p.ImportPath != target {
		for _, p1 := range p.Internal.Imports {
			if p1.ImportPath == target || str.Contains(p1.Deps, target) {
				stk = append(stk, p1.ImportPath)
				p = p1
				continue Search
			}
		}
		// Can't happen, but in case it does...
		stk = append(stk, "<lost path to cycle>")
		break
	}
	return stk
}

// recompileForTest copies and replaces certain packages in pmain's dependency
// graph. This is necessary for two reasons. First, if ptest is different than
// preal, packages that import the package under test should get ptest instead
// of preal. This is particularly important if pxtest depends on functionality
// exposed in test sources in ptest. Second, if there is a main package
// (other than pmain) anywhere, we need to set p.Internal.ForceLibrary and
// clear p.Internal.BuildInfo in the test copy to prevent link conflicts.
// This may happen if both -coverpkg and the command line patterns include
// multiple main packages.
func recompileForTest(pmain, preal, ptest, pxtest *Package) {
	// The "test copy" of preal is ptest.
	// For each package that depends on preal, make a "test copy"
	// that depends on ptest. And so on, up the dependency tree.
	testCopy := map[*Package]*Package{preal: ptest}
	for _, p := range PackageList([]*Package{pmain}) {
		if p == preal {
			continue
		}
		// Copy on write.
		didSplit := p == pmain || p == pxtest
		split := func() {
			if didSplit {
				return
			}
			didSplit = true
			if testCopy[p] != nil {
				panic("recompileForTest loop")
			}
			p1 := new(Package)
			testCopy[p] = p1
			*p1 = *p
			p1.ForTest = preal.ImportPath
			p1.Internal.Imports = make([]*Package, len(p.Internal.Imports))
			copy(p1.Internal.Imports, p.Internal.Imports)
			p1.Imports = make([]string, len(p.Imports))
			copy(p1.Imports, p.Imports)
			p = p1
			p.Target = ""
			p.Internal.BuildInfo = ""
			p.Internal.ForceLibrary = true
		}

		// Update p.Internal.Imports to use test copies.
		for i, imp := range p.Internal.Imports {
			if p1 := testCopy[imp]; p1 != nil && p1 != imp {
				split()
				p.Internal.Imports[i] = p1
			}
		}

		// Don't compile build info from a main package. This can happen
		// if -coverpkg patterns include main packages, since those packages
		// are imported by pmain. See golang.org/issue/30907.
		if p.Internal.BuildInfo != "" && p != pmain {
			split()
		}
	}
}

// isTestFunc tells whether fn has the type of a testing function. arg
// specifies the parameter type we look for: B, M or T.
func isTestFunc(fn *ast.FuncDecl, arg string) bool {
	if fn.Type.Results != nil && len(fn.Type.Results.List) > 0 ||
		fn.Type.Params.List == nil ||
		len(fn.Type.Params.List) != 1 ||
		len(fn.Type.Params.List[0].Names) > 1 {
		return false
	}
	ptr, ok := fn.Type.Params.List[0].Type.(*ast.StarExpr)
	if !ok {
		return false
	}
	// We can't easily check that the type is *testing.M
	// because we don't know how testing has been imported,
	// but at least check that it's *M or *something.M.
	// Same applies for B and T.
	if name, ok := ptr.X.(*ast.Ident); ok && name.Name == arg {
		return true
	}
	if sel, ok := ptr.X.(*ast.SelectorExpr); ok && sel.Sel.Name == arg {
		return true
	}
	return false
}

// isTest tells whether name looks like a test (or benchmark, according to prefix).
// It is a Test (say) if there is a character after Test that is not a lower-case letter.
// We don't want TesticularCancer.
func isTest(name, prefix string) bool {
	if !strings.HasPrefix(name, prefix) {
		return false
	}
	if len(name) == len(prefix) { // "Test" is ok
		return true
	}
	rune, _ := utf8.DecodeRuneInString(name[len(prefix):])
	return !unicode.IsLower(rune)
}

type coverInfo struct {
	Package *Package
	Vars    map[string]*CoverVar
}

// loadTestFuncs returns the testFuncs describing the tests that will be run.
func loadTestFuncs(ptest *Package) (*testFuncs, error) {
	t := &testFuncs{
		Package: ptest,
	}
	for _, file := range ptest.TestGoFiles {
		if err := t.load(filepath.Join(ptest.Dir, file), "_test", &t.ImportTest, &t.NeedTest); err != nil {
			return nil, err
		}
	}
	for _, file := range ptest.XTestGoFiles {
		if err := t.load(filepath.Join(ptest.Dir, file), "_xtest", &t.ImportXtest, &t.NeedXtest); err != nil {
			return nil, err
		}
	}
	return t, nil
}

// formatTestmain returns the content of the _testmain.go file for t.
func formatTestmain(t *testFuncs) ([]byte, error) {
	var buf bytes.Buffer
	if err := testmainTmpl.Execute(&buf, t); err != nil {
		return nil, err
	}
	return buf.Bytes(), nil
}

type testFuncs struct {
	Tests       []testFunc
	Benchmarks  []testFunc
	Examples    []testFunc
	TestMain    *testFunc
	Package     *Package
	ImportTest  bool
	NeedTest    bool
	ImportXtest bool
	NeedXtest   bool
	Cover       *TestCover
}

// ImportPath returns the import path of the package being tested, if it is within GOPATH.
// This is printed by the testing package when running benchmarks.
func (t *testFuncs) ImportPath() string {
	pkg := t.Package.ImportPath
	if strings.HasPrefix(pkg, "_/") {
		return ""
	}
	if pkg == "command-line-arguments" {
		return ""
	}
	return pkg
}

// Covered returns a string describing which packages are being tested for coverage.
// If the covered package is the same as the tested package, it returns the empty string.
// Otherwise it is a comma-separated human-readable list of packages beginning with
// " in", ready for use in the coverage message.
func (t *testFuncs) Covered() string {
	if t.Cover == nil || t.Cover.Paths == nil {
		return ""
	}
	return " in " + strings.Join(t.Cover.Paths, ", ")
}

// Tested returns the name of the package being tested.
func (t *testFuncs) Tested() string {
	return t.Package.Name
}

type testFunc struct {
	Package   string // imported package name (_test or _xtest)
	Name      string // function name
	Output    string // output, for examples
	Unordered bool   // output is allowed to be unordered.
}

var testFileSet = token.NewFileSet()

func (t *testFuncs) load(filename, pkg string, doImport, seen *bool) error {
	f, err := parser.ParseFile(testFileSet, filename, nil, parser.ParseComments)
	if err != nil {
		return base.ExpandScanner(err)
	}
	for _, d := range f.Decls {
		n, ok := d.(*ast.FuncDecl)
		if !ok {
			continue
		}
		if n.Recv != nil {
			continue
		}
		name := n.Name.String()
		switch {
		case name == "TestMain":
			if isTestFunc(n, "T") {
				t.Tests = append(t.Tests, testFunc{pkg, name, "", false})
				*doImport, *seen = true, true
				continue
			}
			err := checkTestFunc(n, "M")
			if err != nil {
				return err
			}
			if t.TestMain != nil {
				return errors.New("multiple definitions of TestMain")
			}
			t.TestMain = &testFunc{pkg, name, "", false}
			*doImport, *seen = true, true
		case isTest(name, "Test"):
			err := checkTestFunc(n, "T")
			if err != nil {
				return err
			}
			t.Tests = append(t.Tests, testFunc{pkg, name, "", false})
			*doImport, *seen = true, true
		case isTest(name, "Benchmark"):
			err := checkTestFunc(n, "B")
			if err != nil {
				return err
			}
			t.Benchmarks = append(t.Benchmarks, testFunc{pkg, name, "", false})
			*doImport, *seen = true, true
		}
	}
	ex := doc.Examples(f)
	sort.Slice(ex, func(i, j int) bool { return ex[i].Order < ex[j].Order })
	for _, e := range ex {
		*doImport = true // import test file whether executed or not
		if e.Output == "" && !e.EmptyOutput {
			// Don't run examples with no output.
			continue
		}
		t.Examples = append(t.Examples, testFunc{pkg, "Example" + e.Name, e.Output, e.Unordered})
		*seen = true
	}
	return nil
}

func checkTestFunc(fn *ast.FuncDecl, arg string) error {
	if !isTestFunc(fn, arg) {
		name := fn.Name.String()
		pos := testFileSet.Position(fn.Pos())
		return fmt.Errorf("%s: wrong signature for %s, must be: func %s(%s *testing.%s)", pos, name, name, strings.ToLower(arg), arg)
	}
	return nil
}

var testmainTmpl = template.Must(template.New("main").Parse(`
package main

import (
{{if not .TestMain}}
	"os"
{{end}}
	"testing"
	"testing/internal/testdeps"

{{if .ImportTest}}
	{{if .NeedTest}}_test{{else}}_{{end}} {{.Package.ImportPath | printf "%q"}}
{{end}}
{{if .ImportXtest}}
	{{if .NeedXtest}}_xtest{{else}}_{{end}} {{.Package.ImportPath | printf "%s_test" | printf "%q"}}
{{end}}
{{if .Cover}}
{{range $i, $p := .Cover.Vars}}
	_cover{{$i}} {{$p.Package.ImportPath | printf "%q"}}
{{end}}
{{end}}
)

var tests = []testing.InternalTest{
{{range .Tests}}
	{"{{.Name}}", {{.Package}}.{{.Name}}},
{{end}}
}

var benchmarks = []testing.InternalBenchmark{
{{range .Benchmarks}}
	{"{{.Name}}", {{.Package}}.{{.Name}}},
{{end}}
}

var examples = []testing.InternalExample{
{{range .Examples}}
	{"{{.Name}}", {{.Package}}.{{.Name}}, {{.Output | printf "%q"}}, {{.Unordered}}},
{{end}}
}

func init() {
	testdeps.ImportPath = {{.ImportPath | printf "%q"}}
}

{{if .Cover}}

// Only updated by init functions, so no need for atomicity.
var (
	coverCounters = make(map[string][]uint32)
	coverBlocks = make(map[string][]testing.CoverBlock)
)

func init() {
	{{range $i, $p := .Cover.Vars}}
	{{range $file, $cover := $p.Vars}}
	coverRegisterFile({{printf "%q" $cover.File}}, _cover{{$i}}.{{$cover.Var}}.Count[:], _cover{{$i}}.{{$cover.Var}}.Pos[:], _cover{{$i}}.{{$cover.Var}}.NumStmt[:])
	{{end}}
	{{end}}
}

func coverRegisterFile(fileName string, counter []uint32, pos []uint32, numStmts []uint16) {
	if 3*len(counter) != len(pos) || len(counter) != len(numStmts) {
		panic("coverage: mismatched sizes")
	}
	if coverCounters[fileName] != nil {
		// Already registered.
		return
	}
	coverCounters[fileName] = counter
	block := make([]testing.CoverBlock, len(counter))
	for i := range counter {
		block[i] = testing.CoverBlock{
			Line0: pos[3*i+0],
			Col0: uint16(pos[3*i+2]),
			Line1: pos[3*i+1],
			Col1: uint16(pos[3*i+2]>>16),
			Stmts: numStmts[i],
		}
	}
	coverBlocks[fileName] = block
}
{{end}}

func main() {
{{if .Cover}}
	testing.RegisterCover(testing.Cover{
		Mode: {{printf "%q" .Cover.Mode}},
		Counters: coverCounters,
		Blocks: coverBlocks,
		CoveredPackages: {{printf "%q" .Covered}},
	})
{{end}}
	m := testing.MainStart(testdeps.TestDeps{}, tests, benchmarks, examples)
{{with .TestMain}}
	{{.Package}}.{{.Name}}(m)
{{else}}
	os.Exit(m.Run())
{{end}}
}

`))