* tree-ssa-reassoc.c (reassociate_bb): Clarify code slighly.

[official-gcc.git] / libgo / go / go / printer / printer_test.go

// Copyright 2009 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 printer

import (
        "bytes"
        "errors"
        "flag"
        "fmt"
        "go/ast"
        "go/parser"
        "go/token"
        "io"
        "io/ioutil"
        "path/filepath"
        "testing"
        "time"
)

const (
        dataDir  = "testdata"
        tabwidth = 8
)

var update = flag.Bool("update", false, "update golden files")

var fset = token.NewFileSet()

type checkMode uint

const (
        export checkMode = 1 << iota
        rawFormat
        idempotent
)

// format parses src, prints the corresponding AST, verifies the resulting
// src is syntactically correct, and returns the resulting src or an error
// if any.
func format(src []byte, mode checkMode) ([]byte, error) {
        // parse src
        f, err := parser.ParseFile(fset, "", src, parser.ParseComments)
        if err != nil {
                return nil, fmt.Errorf("parse: %s\n%s", err, src)
        }

        // filter exports if necessary
        if mode&export != 0 {
                ast.FileExports(f) // ignore result
                f.Comments = nil   // don't print comments that are not in AST
        }

        // determine printer configuration
        cfg := Config{Tabwidth: tabwidth}
        if mode&rawFormat != 0 {
                cfg.Mode |= RawFormat
        }

        // print AST
        var buf bytes.Buffer
        if err := cfg.Fprint(&buf, fset, f); err != nil {
                return nil, fmt.Errorf("print: %s", err)
        }

        // make sure formatted output is syntactically correct
        res := buf.Bytes()
        if _, err := parser.ParseFile(fset, "", res, 0); err != nil {
                return nil, fmt.Errorf("re-parse: %s\n%s", err, buf.Bytes())
        }

        return res, nil
}

// lineAt returns the line in text starting at offset offs.
func lineAt(text []byte, offs int) []byte {
        i := offs
        for i < len(text) && text[i] != '\n' {
                i++
        }
        return text[offs:i]
}

// diff compares a and b.
func diff(aname, bname string, a, b []byte) error {
        var buf bytes.Buffer // holding long error message

        // compare lengths
        if len(a) != len(b) {
                fmt.Fprintf(&buf, "\nlength changed: len(%s) = %d, len(%s) = %d", aname, len(a), bname, len(b))
        }

        // compare contents
        line := 1
        offs := 1
        for i := 0; i < len(a) && i < len(b); i++ {
                ch := a[i]
                if ch != b[i] {
                        fmt.Fprintf(&buf, "\n%s:%d:%d: %s", aname, line, i-offs+1, lineAt(a, offs))
                        fmt.Fprintf(&buf, "\n%s:%d:%d: %s", bname, line, i-offs+1, lineAt(b, offs))
                        fmt.Fprintf(&buf, "\n\n")
                        break
                }
                if ch == '\n' {
                        line++
                        offs = i + 1
                }
        }

        if buf.Len() > 0 {
                return errors.New(buf.String())
        }
        return nil
}

func runcheck(t *testing.T, source, golden string, mode checkMode) {
        src, err := ioutil.ReadFile(source)
        if err != nil {
                t.Error(err)
                return
        }

        res, err := format(src, mode)
        if err != nil {
                t.Error(err)
                return
        }

        // update golden files if necessary
        if *update {
                if err := ioutil.WriteFile(golden, res, 0644); err != nil {
                        t.Error(err)
                }
                return
        }

        // get golden
        gld, err := ioutil.ReadFile(golden)
        if err != nil {
                t.Error(err)
                return
        }

        // formatted source and golden must be the same
        if err := diff(source, golden, res, gld); err != nil {
                t.Error(err)
                return
        }

        if mode&idempotent != 0 {
                // formatting golden must be idempotent
                // (This is very difficult to achieve in general and for now
                // it is only checked for files explicitly marked as such.)
                res, err = format(gld, mode)
                if err := diff(golden, fmt.Sprintf("format(%s)", golden), gld, res); err != nil {
                        t.Errorf("golden is not idempotent: %s", err)
                }
        }
}

func check(t *testing.T, source, golden string, mode checkMode) {
        // run the test
        cc := make(chan int)
        go func() {
                runcheck(t, source, golden, mode)
                cc <- 0
        }()

        // wait with timeout
        select {
        case <-time.After(10 * time.Second): // plenty of a safety margin, even for very slow machines
                // test running past time out
                t.Errorf("%s: running too slowly", source)
        case <-cc:
                // test finished within allotted time margin
        }
}

type entry struct {
        source, golden string
        mode           checkMode
}

// Use go test -update to create/update the respective golden files.
var data = []entry{
        {"empty.input", "empty.golden", idempotent},
        {"comments.input", "comments.golden", 0},
        {"comments.input", "comments.x", export},
        {"comments2.input", "comments2.golden", idempotent},
        {"linebreaks.input", "linebreaks.golden", idempotent},
        {"expressions.input", "expressions.golden", idempotent},
        {"expressions.input", "expressions.raw", rawFormat | idempotent},
        {"declarations.input", "declarations.golden", 0},
        {"statements.input", "statements.golden", 0},
        {"slow.input", "slow.golden", idempotent},
}

func TestFiles(t *testing.T) {
        t.Parallel()
        for _, e := range data {
                source := filepath.Join(dataDir, e.source)
                golden := filepath.Join(dataDir, e.golden)
                mode := e.mode
                t.Run(e.source, func(t *testing.T) {
                        t.Parallel()
                        check(t, source, golden, mode)
                        // TODO(gri) check that golden is idempotent
                        //check(t, golden, golden, e.mode)
                })
        }
}

// TestLineComments, using a simple test case, checks that consecutive line
// comments are properly terminated with a newline even if the AST position
// information is incorrect.
//
func TestLineComments(t *testing.T) {
        const src = `// comment 1
        // comment 2
        // comment 3
        package main
        `

        fset := token.NewFileSet()
        f, err := parser.ParseFile(fset, "", src, parser.ParseComments)
        if err != nil {
                panic(err) // error in test
        }

        var buf bytes.Buffer
        fset = token.NewFileSet() // use the wrong file set
        Fprint(&buf, fset, f)

        nlines := 0
        for _, ch := range buf.Bytes() {
                if ch == '\n' {
                        nlines++
                }
        }

        const expected = 3
        if nlines < expected {
                t.Errorf("got %d, expected %d\n", nlines, expected)
                t.Errorf("result:\n%s", buf.Bytes())
        }
}

// Verify that the printer can be invoked during initialization.
func init() {
        const name = "foobar"
        var buf bytes.Buffer
        if err := Fprint(&buf, fset, &ast.Ident{Name: name}); err != nil {
                panic(err) // error in test
        }
        // in debug mode, the result contains additional information;
        // ignore it
        if s := buf.String(); !debug && s != name {
                panic("got " + s + ", want " + name)
        }
}

// Verify that the printer doesn't crash if the AST contains BadXXX nodes.
func TestBadNodes(t *testing.T) {
        const src = "package p\n("
        const res = "package p\nBadDecl\n"
        f, err := parser.ParseFile(fset, "", src, parser.ParseComments)
        if err == nil {
                t.Error("expected illegal program") // error in test
        }
        var buf bytes.Buffer
        Fprint(&buf, fset, f)
        if buf.String() != res {
                t.Errorf("got %q, expected %q", buf.String(), res)
        }
}

// testComment verifies that f can be parsed again after printing it
// with its first comment set to comment at any possible source offset.
func testComment(t *testing.T, f *ast.File, srclen int, comment *ast.Comment) {
        f.Comments[0].List[0] = comment
        var buf bytes.Buffer
        for offs := 0; offs <= srclen; offs++ {
                buf.Reset()
                // Printing f should result in a correct program no
                // matter what the (incorrect) comment position is.
                if err := Fprint(&buf, fset, f); err != nil {
                        t.Error(err)
                }
                if _, err := parser.ParseFile(fset, "", buf.Bytes(), 0); err != nil {
                        t.Fatalf("incorrect program for pos = %d:\n%s", comment.Slash, buf.String())
                }
                // Position information is just an offset.
                // Move comment one byte down in the source.
                comment.Slash++
        }
}

// Verify that the printer produces a correct program
// even if the position information of comments introducing newlines
// is incorrect.
func TestBadComments(t *testing.T) {
        t.Parallel()
        const src = `
// first comment - text and position changed by test
package p
import "fmt"
const pi = 3.14 // rough circle
var (
        x, y, z int = 1, 2, 3
        u, v float64
)
func fibo(n int) {
        if n < 2 {
                return n /* seed values */
        }
        return fibo(n-1) + fibo(n-2)
}
`

        f, err := parser.ParseFile(fset, "", src, parser.ParseComments)
        if err != nil {
                t.Error(err) // error in test
        }

        comment := f.Comments[0].List[0]
        pos := comment.Pos()
        if fset.Position(pos).Offset != 1 {
                t.Error("expected offset 1") // error in test
        }

        testComment(t, f, len(src), &ast.Comment{Slash: pos, Text: "//-style comment"})
        testComment(t, f, len(src), &ast.Comment{Slash: pos, Text: "/*-style comment */"})
        testComment(t, f, len(src), &ast.Comment{Slash: pos, Text: "/*-style \n comment */"})
        testComment(t, f, len(src), &ast.Comment{Slash: pos, Text: "/*-style comment \n\n\n */"})
}

type visitor chan *ast.Ident

func (v visitor) Visit(n ast.Node) (w ast.Visitor) {
        if ident, ok := n.(*ast.Ident); ok {
                v <- ident
        }
        return v
}

// idents is an iterator that returns all idents in f via the result channel.
func idents(f *ast.File) <-chan *ast.Ident {
        v := make(visitor)
        go func() {
                ast.Walk(v, f)
                close(v)
        }()
        return v
}

// identCount returns the number of identifiers found in f.
func identCount(f *ast.File) int {
        n := 0
        for range idents(f) {
                n++
        }
        return n
}

// Verify that the SourcePos mode emits correct //line directives
// by testing that position information for matching identifiers
// is maintained.
func TestSourcePos(t *testing.T) {
        const src = `
package p
import ( "go/printer"; "math" )
const pi = 3.14; var x = 0
type t struct{ x, y, z int; u, v, w float32 }
func (t *t) foo(a, b, c int) int {
        return a*t.x + b*t.y +
                // two extra lines here
                // ...
                c*t.z
}
`

        // parse original
        f1, err := parser.ParseFile(fset, "src", src, parser.ParseComments)
        if err != nil {
                t.Fatal(err)
        }

        // pretty-print original
        var buf bytes.Buffer
        err = (&Config{Mode: UseSpaces | SourcePos, Tabwidth: 8}).Fprint(&buf, fset, f1)
        if err != nil {
                t.Fatal(err)
        }

        // parse pretty printed original
        // (//line directives must be interpreted even w/o parser.ParseComments set)
        f2, err := parser.ParseFile(fset, "", buf.Bytes(), 0)
        if err != nil {
                t.Fatalf("%s\n%s", err, buf.Bytes())
        }

        // At this point the position information of identifiers in f2 should
        // match the position information of corresponding identifiers in f1.

        // number of identifiers must be > 0 (test should run) and must match
        n1 := identCount(f1)
        n2 := identCount(f2)
        if n1 == 0 {
                t.Fatal("got no idents")
        }
        if n2 != n1 {
                t.Errorf("got %d idents; want %d", n2, n1)
        }

        // verify that all identifiers have correct line information
        i2range := idents(f2)
        for i1 := range idents(f1) {
                i2 := <-i2range

                if i2.Name != i1.Name {
                        t.Errorf("got ident %s; want %s", i2.Name, i1.Name)
                }

                l1 := fset.Position(i1.Pos()).Line
                l2 := fset.Position(i2.Pos()).Line
                if l2 != l1 {
                        t.Errorf("got line %d; want %d for %s", l2, l1, i1.Name)
                }
        }

        if t.Failed() {
                t.Logf("\n%s", buf.Bytes())
        }
}

// Verify that the SourcePos mode doesn't emit unnecessary //line directives
// before empty lines.
func TestIssue5945(t *testing.T) {
        const orig = `
package p   // line 2
func f() {} // line 3

var x, y, z int


func g() { // line 8
}
`

        const want = `//line src.go:2
package p

//line src.go:3
func f() {}

var x, y, z int

//line src.go:8
func g() {
}
`

        // parse original
        f1, err := parser.ParseFile(fset, "src.go", orig, 0)
        if err != nil {
                t.Fatal(err)
        }

        // pretty-print original
        var buf bytes.Buffer
        err = (&Config{Mode: UseSpaces | SourcePos, Tabwidth: 8}).Fprint(&buf, fset, f1)
        if err != nil {
                t.Fatal(err)
        }
        got := buf.String()

        // compare original with desired output
        if got != want {
                t.Errorf("got:\n%s\nwant:\n%s\n", got, want)
        }
}

var decls = []string{
        `import "fmt"`,
        "const pi = 3.1415\nconst e = 2.71828\n\nvar x = pi",
        "func sum(x, y int) int\t{ return x + y }",
}

func TestDeclLists(t *testing.T) {
        for _, src := range decls {
                file, err := parser.ParseFile(fset, "", "package p;"+src, parser.ParseComments)
                if err != nil {
                        panic(err) // error in test
                }

                var buf bytes.Buffer
                err = Fprint(&buf, fset, file.Decls) // only print declarations
                if err != nil {
                        panic(err) // error in test
                }

                out := buf.String()
                if out != src {
                        t.Errorf("\ngot : %q\nwant: %q\n", out, src)
                }
        }
}

var stmts = []string{
        "i := 0",
        "select {}\nvar a, b = 1, 2\nreturn a + b",
        "go f()\ndefer func() {}()",
}

func TestStmtLists(t *testing.T) {
        for _, src := range stmts {
                file, err := parser.ParseFile(fset, "", "package p; func _() {"+src+"}", parser.ParseComments)
                if err != nil {
                        panic(err) // error in test
                }

                var buf bytes.Buffer
                err = Fprint(&buf, fset, file.Decls[0].(*ast.FuncDecl).Body.List) // only print statements
                if err != nil {
                        panic(err) // error in test
                }

                out := buf.String()
                if out != src {
                        t.Errorf("\ngot : %q\nwant: %q\n", out, src)
                }
        }
}

func TestBaseIndent(t *testing.T) {
        t.Parallel()
        // The testfile must not contain multi-line raw strings since those
        // are not indented (because their values must not change) and make
        // this test fail.
        const filename = "printer.go"
        src, err := ioutil.ReadFile(filename)
        if err != nil {
                panic(err) // error in test
        }

        file, err := parser.ParseFile(fset, filename, src, 0)
        if err != nil {
                panic(err) // error in test
        }

        for indent := 0; indent < 4; indent++ {
                indent := indent
                t.Run(fmt.Sprint(indent), func(t *testing.T) {
                        t.Parallel()
                        var buf bytes.Buffer
                        (&Config{Tabwidth: tabwidth, Indent: indent}).Fprint(&buf, fset, file)
                        // all code must be indented by at least 'indent' tabs
                        lines := bytes.Split(buf.Bytes(), []byte{'\n'})
                        for i, line := range lines {
                                if len(line) == 0 {
                                        continue // empty lines don't have indentation
                                }
                                n := 0
                                for j, b := range line {
                                        if b != '\t' {
                                                // end of indentation
                                                n = j
                                                break
                                        }
                                }
                                if n < indent {
                                        t.Errorf("line %d: got only %d tabs; want at least %d: %q", i, n, indent, line)
                                }
                        }
                })
        }
}

// TestFuncType tests that an ast.FuncType with a nil Params field
// can be printed (per go/ast specification). Test case for issue 3870.
func TestFuncType(t *testing.T) {
        src := &ast.File{
                Name: &ast.Ident{Name: "p"},
                Decls: []ast.Decl{
                        &ast.FuncDecl{
                                Name: &ast.Ident{Name: "f"},
                                Type: &ast.FuncType{},
                        },
                },
        }

        var buf bytes.Buffer
        if err := Fprint(&buf, fset, src); err != nil {
                t.Fatal(err)
        }
        got := buf.String()

        const want = `package p

func f()
`

        if got != want {
                t.Fatalf("got:\n%s\nwant:\n%s\n", got, want)
        }
}

type limitWriter struct {
        remaining int
        errCount  int
}

func (l *limitWriter) Write(buf []byte) (n int, err error) {
        n = len(buf)
        if n >= l.remaining {
                n = l.remaining
                err = io.EOF
                l.errCount++
        }
        l.remaining -= n
        return n, err
}

// Test whether the printer stops writing after the first error
func TestWriteErrors(t *testing.T) {
        t.Parallel()
        const filename = "printer.go"
        src, err := ioutil.ReadFile(filename)
        if err != nil {
                panic(err) // error in test
        }
        file, err := parser.ParseFile(fset, filename, src, 0)
        if err != nil {
                panic(err) // error in test
        }
        for i := 0; i < 20; i++ {
                lw := &limitWriter{remaining: i}
                err := (&Config{Mode: RawFormat}).Fprint(lw, fset, file)
                if lw.errCount > 1 {
                        t.Fatal("Writes continued after first error returned")
                }
                // We expect errCount be 1 iff err is set
                if (lw.errCount != 0) != (err != nil) {
                        t.Fatal("Expected err when errCount != 0")
                }
        }
}

// TextX is a skeleton test that can be filled in for debugging one-off cases.
// Do not remove.
func TestX(t *testing.T) {
        const src = `
package p
func _() {}
`
        _, err := format([]byte(src), 0)
        if err != nil {
                t.Error(err)
        }
}

func TestCommentedNode(t *testing.T) {
        const (
                input = `package main

func foo() {
        // comment inside func
}

// leading comment
type bar int // comment2

`

                foo = `func foo() {
        // comment inside func
}`

                bar = `// leading comment
type bar int    // comment2
`
        )

        fset := token.NewFileSet()
        f, err := parser.ParseFile(fset, "input.go", input, parser.ParseComments)
        if err != nil {
                t.Fatal(err)
        }

        var buf bytes.Buffer

        err = Fprint(&buf, fset, &CommentedNode{Node: f.Decls[0], Comments: f.Comments})
        if err != nil {
                t.Fatal(err)
        }

        if buf.String() != foo {
                t.Errorf("got %q, want %q", buf.String(), foo)
        }

        buf.Reset()

        err = Fprint(&buf, fset, &CommentedNode{Node: f.Decls[1], Comments: f.Comments})
        if err != nil {
                t.Fatal(err)
        }

        if buf.String() != bar {
                t.Errorf("got %q, want %q", buf.String(), bar)
        }
}