| // Copyright 2013 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. |
| |
| // Cover is a program for analyzing the coverage profiles generated by |
| // 'go test -coverprofile'. |
| // |
| // Cover is also used by 'go test -cover' to rewrite the source code with |
| // annotations to track which parts of each function are executed. |
| // It operates on one Go source file at a time, computing approximate |
| // basic block information by studying the source. It is thus more portable |
| // than binary-rewriting coverage tools, but also a little less capable. |
| // For instance, it does not probe inside && and || expressions, and can |
| // be mildly confused by single statements with multiple function literals. |
| |
| package main |
| |
| import ( |
| "flag" |
| "fmt" |
| "go/ast" |
| "go/parser" |
| "go/printer" |
| "go/token" |
| "io" |
| "log" |
| "os" |
| "sort" |
| "strconv" |
| ) |
| |
| const usageMessage = "" + |
| `Usage of 'go tool cover': |
| Given a coverage profile produced by 'go test -coverprofile=c.out', open |
| a web browser displaying annotated source code: |
| go tool cover -html=c.out |
| The same, but write the generated HTML to a file instead of starting a browser: |
| go tool cover -html=c.out -o coverage.html |
| Write to standard output coverage percentages for each function: |
| go tool cover -func=c.out |
| Generate modified source code with coverage annotations (what go test -cover does): |
| go tool cover -mode=set -var=CoverageVariableName program.go |
| |
| Only one of -html, -func, or -mode may be set. |
| ` |
| |
| func usage() { |
| fmt.Fprintln(os.Stderr, usageMessage) |
| fmt.Fprintln(os.Stderr, "Flags:") |
| flag.PrintDefaults() |
| os.Exit(2) |
| } |
| |
| var ( |
| mode = flag.String("mode", "", "coverage mode: set, count, atomic") |
| varVar = flag.String("var", "GoCover", "name of coverage variable to generate") |
| output = flag.String("o", "", "file for output; default: stdout") |
| htmlOut = flag.String("html", "", "generate HTML representation of coverage profile") |
| funcOut = flag.String("func", "", "output coverage profile information for each function") |
| ) |
| |
| var profile string // The profile to read; the value of -html but stored separately for future flexibility. |
| |
| var counterStmt func(*File, ast.Expr) ast.Stmt |
| |
| const ( |
| atomicPackagePath = "sync/atomic" |
| atomicPackageName = "_cover_atomic_" |
| ) |
| |
| func main() { |
| flag.Usage = usage |
| flag.Parse() |
| |
| profile = *htmlOut |
| if *funcOut != "" { |
| if profile != "" { |
| flag.Usage() |
| } |
| profile = *funcOut |
| } |
| |
| // Must either display a profile or rewrite Go source. |
| if (profile == "") == (*mode == "") { |
| flag.Usage() |
| } |
| |
| // Generate HTML or function coverage information. |
| if profile != "" { |
| if flag.NArg() != 0 { |
| flag.Usage() |
| } |
| var err error |
| if *htmlOut != "" { |
| err = htmlOutput(profile, *output) |
| } else { |
| err = funcOutput(profile, *output) |
| } |
| if err != nil { |
| fmt.Fprintf(os.Stderr, "cover: %v\n", err) |
| os.Exit(2) |
| } |
| return |
| } |
| |
| // Generate coverage-annotated source. |
| switch *mode { |
| case "set": |
| counterStmt = setCounterStmt |
| case "count": |
| counterStmt = incCounterStmt |
| case "atomic": |
| counterStmt = atomicCounterStmt |
| default: |
| flag.Usage() |
| } |
| if flag.NArg() != 1 { |
| flag.Usage() |
| } |
| cover(flag.Arg(0)) |
| } |
| |
| // Block represents the information about a basic block to be recorded in the analysis. |
| // Note: Our definition of basic block is based on control structures; we don't break |
| // apart && and ||. We could but it doesn't seem important enough to bother. |
| type Block struct { |
| startByte token.Pos |
| endByte token.Pos |
| numStmt int |
| } |
| |
| // File is a wrapper for the state of a file used in the parser. |
| // The basic parse tree walker is a method of this type. |
| type File struct { |
| fset *token.FileSet |
| name string // Name of file. |
| astFile *ast.File |
| blocks []Block |
| atomicPkg string // Package name for "sync/atomic" in this file. |
| } |
| |
| // Visit implements the ast.Visitor interface. |
| func (f *File) Visit(node ast.Node) ast.Visitor { |
| switch n := node.(type) { |
| case *ast.BlockStmt: |
| // If it's a switch or select, the body is a list of case clauses; don't tag the block itself. |
| if len(n.List) > 0 { |
| switch n.List[0].(type) { |
| case *ast.CaseClause: // switch |
| for _, n := range n.List { |
| clause := n.(*ast.CaseClause) |
| clause.Body = f.addCounters(clause.Pos(), clause.End(), clause.Body, false) |
| } |
| return f |
| case *ast.CommClause: // select |
| for _, n := range n.List { |
| clause := n.(*ast.CommClause) |
| clause.Body = f.addCounters(clause.Pos(), clause.End(), clause.Body, false) |
| } |
| return f |
| } |
| } |
| n.List = f.addCounters(n.Lbrace, n.Rbrace+1, n.List, true) // +1 to step past closing brace. |
| case *ast.IfStmt: |
| ast.Walk(f, n.Body) |
| if n.Else == nil { |
| return nil |
| } |
| // The elses are special, because if we have |
| // if x { |
| // } else if y { |
| // } |
| // we want to cover the "if y". To do this, we need a place to drop the counter, |
| // so we add a hidden block: |
| // if x { |
| // } else { |
| // if y { |
| // } |
| // } |
| const backupToElse = token.Pos(len("else ")) // The AST doesn't remember the else location. We can make an accurate guess. |
| switch stmt := n.Else.(type) { |
| case *ast.IfStmt: |
| block := &ast.BlockStmt{ |
| Lbrace: stmt.If - backupToElse, // So the covered part looks like it starts at the "else". |
| List: []ast.Stmt{stmt}, |
| Rbrace: stmt.End(), |
| } |
| n.Else = block |
| case *ast.BlockStmt: |
| stmt.Lbrace -= backupToElse // So the block looks like it starts at the "else". |
| default: |
| panic("unexpected node type in if") |
| } |
| ast.Walk(f, n.Else) |
| return nil |
| case *ast.SelectStmt: |
| // Don't annotate an empty select - creates a syntax error. |
| if n.Body == nil || len(n.Body.List) == 0 { |
| return nil |
| } |
| case *ast.SwitchStmt: |
| // Don't annotate an empty switch - creates a syntax error. |
| if n.Body == nil || len(n.Body.List) == 0 { |
| return nil |
| } |
| } |
| return f |
| } |
| |
| // unquote returns the unquoted string. |
| func unquote(s string) string { |
| t, err := strconv.Unquote(s) |
| if err != nil { |
| log.Fatalf("cover: improperly quoted string %q\n", s) |
| } |
| return t |
| } |
| |
| // addImport adds an import for the specified path, if one does not already exist, and returns |
| // the local package name. |
| func (f *File) addImport(path string) string { |
| // Does the package already import it? |
| for _, s := range f.astFile.Imports { |
| if unquote(s.Path.Value) == path { |
| return s.Name.Name |
| } |
| } |
| newImport := &ast.ImportSpec{ |
| Name: ast.NewIdent(atomicPackageName), |
| Path: &ast.BasicLit{ |
| Kind: token.STRING, |
| Value: fmt.Sprintf("%q", path), |
| }, |
| } |
| impDecl := &ast.GenDecl{ |
| Tok: token.IMPORT, |
| Specs: []ast.Spec{ |
| newImport, |
| }, |
| } |
| // Make the new import the first Decl in the file. |
| astFile := f.astFile |
| astFile.Decls = append(astFile.Decls, nil) |
| copy(astFile.Decls[1:], astFile.Decls[0:]) |
| astFile.Decls[0] = impDecl |
| astFile.Imports = append(astFile.Imports, newImport) |
| |
| // Now refer to the package, just in case it ends up unused. |
| // That is, append to the end of the file the declaration |
| // var _ = _cover_atomic_.AddUint32 |
| reference := &ast.GenDecl{ |
| Tok: token.VAR, |
| Specs: []ast.Spec{ |
| &ast.ValueSpec{ |
| Names: []*ast.Ident{ |
| ast.NewIdent("_"), |
| }, |
| Values: []ast.Expr{ |
| &ast.SelectorExpr{ |
| X: ast.NewIdent(atomicPackageName), |
| Sel: ast.NewIdent("AddUint32"), |
| }, |
| }, |
| }, |
| }, |
| } |
| astFile.Decls = append(astFile.Decls, reference) |
| return atomicPackageName |
| } |
| |
| func cover(name string) { |
| fset := token.NewFileSet() |
| parsedFile, err := parser.ParseFile(fset, name, nil, 0) |
| if err != nil { |
| log.Fatalf("cover: %s: %s", name, err) |
| } |
| file := &File{ |
| fset: fset, |
| name: name, |
| astFile: parsedFile, |
| } |
| if *mode == "atomic" { |
| file.atomicPkg = file.addImport(atomicPackagePath) |
| } |
| ast.Walk(file, file.astFile) |
| fd := os.Stdout |
| if *output != "" { |
| var err error |
| fd, err = os.Create(*output) |
| if err != nil { |
| log.Fatalf("cover: %s", err) |
| } |
| } |
| file.print(fd) |
| // After printing the source tree, add some declarations for the counters etc. |
| // We could do this by adding to the tree, but it's easier just to print the text. |
| file.addVariables(fd) |
| } |
| |
| func (f *File) print(w io.Writer) { |
| printer.Fprint(w, f.fset, f.astFile) |
| } |
| |
| // intLiteral returns an ast.BasicLit representing the integer value. |
| func (f *File) intLiteral(i int) *ast.BasicLit { |
| node := &ast.BasicLit{ |
| Kind: token.INT, |
| Value: fmt.Sprint(i), |
| } |
| return node |
| } |
| |
| // index returns an ast.BasicLit representing the number of counters present. |
| func (f *File) index() *ast.BasicLit { |
| return f.intLiteral(len(f.blocks)) |
| } |
| |
| // setCounterStmt returns the expression: __count[23] = 1. |
| func setCounterStmt(f *File, counter ast.Expr) ast.Stmt { |
| return &ast.AssignStmt{ |
| Lhs: []ast.Expr{counter}, |
| Tok: token.ASSIGN, |
| Rhs: []ast.Expr{f.intLiteral(1)}, |
| } |
| } |
| |
| // incCounterStmt returns the expression: __count[23]++. |
| func incCounterStmt(f *File, counter ast.Expr) ast.Stmt { |
| return &ast.IncDecStmt{ |
| X: counter, |
| Tok: token.INC, |
| } |
| } |
| |
| // atomicCounterStmt returns the expression: atomic.AddUint32(&__count[23], 1) |
| func atomicCounterStmt(f *File, counter ast.Expr) ast.Stmt { |
| return &ast.ExprStmt{ |
| X: &ast.CallExpr{ |
| Fun: &ast.SelectorExpr{ |
| X: ast.NewIdent(f.atomicPkg), |
| Sel: ast.NewIdent("AddUint32"), |
| }, |
| Args: []ast.Expr{&ast.UnaryExpr{ |
| Op: token.AND, |
| X: counter, |
| }, |
| f.intLiteral(1), |
| }, |
| }, |
| } |
| } |
| |
| // newCounter creates a new counter expression of the appropriate form. |
| func (f *File) newCounter(start, end token.Pos, numStmt int) ast.Stmt { |
| counter := &ast.IndexExpr{ |
| X: &ast.SelectorExpr{ |
| X: ast.NewIdent(*varVar), |
| Sel: ast.NewIdent("Count"), |
| }, |
| Index: f.index(), |
| } |
| stmt := counterStmt(f, counter) |
| f.blocks = append(f.blocks, Block{start, end, numStmt}) |
| return stmt |
| } |
| |
| // addCounters takes a list of statements and adds counters to the beginning of |
| // each basic block at the top level of that list. For instance, given |
| // |
| // S1 |
| // if cond { |
| // S2 |
| // } |
| // S3 |
| // |
| // counters will be added before S1 and before S3. The block containing S2 |
| // will be visited in a separate call. |
| // TODO: Nested simple blocks get unecessary (but correct) counters |
| func (f *File) addCounters(pos, blockEnd token.Pos, list []ast.Stmt, extendToClosingBrace bool) []ast.Stmt { |
| // Special case: make sure we add a counter to an empty block. Can't do this below |
| // or we will add a counter to an empty statement list after, say, a return statement. |
| if len(list) == 0 { |
| return []ast.Stmt{f.newCounter(pos, blockEnd, 0)} |
| } |
| // We have a block (statement list), but it may have several basic blocks due to the |
| // appearance of statements that affect the flow of control. |
| var newList []ast.Stmt |
| for { |
| // Find first statement that affects flow of control (break, continue, if, etc.). |
| // It will be the last statement of this basic block. |
| var last int |
| end := blockEnd |
| for last = 0; last < len(list); last++ { |
| end = f.statementBoundary(list[last]) |
| if f.endsBasicSourceBlock(list[last]) { |
| extendToClosingBrace = false // Block is broken up now. |
| last++ |
| break |
| } |
| } |
| if extendToClosingBrace { |
| end = blockEnd |
| } |
| if pos != end { // Can have no source to cover if e.g. blocks abut. |
| newList = append(newList, f.newCounter(pos, end, last)) |
| } |
| newList = append(newList, list[0:last]...) |
| list = list[last:] |
| if len(list) == 0 { |
| break |
| } |
| pos = list[0].Pos() |
| } |
| return newList |
| } |
| |
| // statementBoundary finds the location in s that terminates the current basic |
| // block in the source. |
| func (f *File) statementBoundary(s ast.Stmt) token.Pos { |
| // Control flow statements are easy. |
| switch s := s.(type) { |
| case *ast.BlockStmt: |
| // Treat blocks like basic blocks to avoid overlapping counters. |
| return s.Lbrace |
| case *ast.IfStmt: |
| return s.Body.Lbrace |
| case *ast.ForStmt: |
| return s.Body.Lbrace |
| case *ast.LabeledStmt: |
| return f.statementBoundary(s.Stmt) |
| case *ast.RangeStmt: |
| return s.Body.Lbrace |
| case *ast.SwitchStmt: |
| return s.Body.Lbrace |
| case *ast.SelectStmt: |
| return s.Body.Lbrace |
| case *ast.TypeSwitchStmt: |
| return s.Body.Lbrace |
| } |
| // If not a control flow statement, it is a declaration, expression, call, etc. and it may have a function literal. |
| // If it does, that's tricky because we want to exclude the body of the function from this block. |
| // Draw a line at the start of the body of the first function literal we find. |
| // TODO: what if there's more than one? Probably doesn't matter much. |
| var literal funcLitFinder |
| ast.Walk(&literal, s) |
| if literal.found() { |
| return token.Pos(literal) |
| } |
| return s.End() |
| } |
| |
| // endsBasicSourceBlock reports whether s changes the flow of control: break, if, etc., |
| // or if it's just problematic, for instance contains a function literal, which will complicate |
| // accounting due to the block-within-an expression. |
| func (f *File) endsBasicSourceBlock(s ast.Stmt) bool { |
| switch s := s.(type) { |
| case *ast.BlockStmt: |
| // Treat blocks like basic blocks to avoid overlapping counters. |
| return true |
| case *ast.BranchStmt: |
| return true |
| case *ast.ForStmt: |
| return true |
| case *ast.IfStmt: |
| return true |
| case *ast.LabeledStmt: |
| return f.endsBasicSourceBlock(s.Stmt) |
| case *ast.RangeStmt: |
| return true |
| case *ast.SwitchStmt: |
| return true |
| case *ast.SelectStmt: |
| return true |
| case *ast.TypeSwitchStmt: |
| return true |
| } |
| var literal funcLitFinder |
| ast.Walk(&literal, s) |
| return literal.found() |
| } |
| |
| // funcLitFinder implements the ast.Visitor pattern to find the location of any |
| // function literal in a subtree. |
| type funcLitFinder token.Pos |
| |
| func (f *funcLitFinder) Visit(node ast.Node) (w ast.Visitor) { |
| if f.found() { |
| return nil // Prune search. |
| } |
| switch n := node.(type) { |
| case *ast.FuncLit: |
| *f = funcLitFinder(n.Body.Lbrace) |
| return nil // Prune search. |
| } |
| return f |
| } |
| |
| func (f *funcLitFinder) found() bool { |
| return token.Pos(*f) != token.NoPos |
| } |
| |
| // Sort interface for []block1; used for self-check in addVariables. |
| |
| type block1 struct { |
| Block |
| index int |
| } |
| |
| type blockSlice []block1 |
| |
| func (b blockSlice) Len() int { return len(b) } |
| func (b blockSlice) Less(i, j int) bool { return b[i].startByte < b[j].startByte } |
| func (b blockSlice) Swap(i, j int) { b[i], b[j] = b[j], b[i] } |
| |
| // addVariables adds to the end of the file the declarations to set up the counter and position variables. |
| func (f *File) addVariables(w io.Writer) { |
| // Self-check: Verify that the instrumented basic blocks are disjoint. |
| t := make([]block1, len(f.blocks)) |
| for i := range f.blocks { |
| t[i].Block = f.blocks[i] |
| t[i].index = i |
| } |
| sort.Sort(blockSlice(t)) |
| for i := 1; i < len(t); i++ { |
| if t[i-1].endByte > t[i].startByte { |
| fmt.Fprintf(os.Stderr, "cover: internal error: block %d overlaps block %d\n", t[i-1].index, t[i].index) |
| fmt.Fprintf(os.Stderr, "\t%s:#%d,#%d %s:#%d,#%d\n", f.name, t[i-1].startByte, t[i-1].endByte, f.name, t[i].startByte, t[i].endByte) |
| } |
| } |
| |
| // Declare the coverage struct as a package-level variable. |
| fmt.Fprintf(w, "\nvar %s = struct {\n", *varVar) |
| fmt.Fprintf(w, "\tCount [%d]uint32\n", len(f.blocks)) |
| fmt.Fprintf(w, "\tPos [3 * %d]uint32\n", len(f.blocks)) |
| fmt.Fprintf(w, "\tNumStmt [%d]uint16\n", len(f.blocks)) |
| fmt.Fprintf(w, "} {\n") |
| |
| // Initialize the position array field. |
| fmt.Fprintf(w, "\tPos: [3 * %d]uint32{\n", len(f.blocks)) |
| |
| // A nice long list of positions. Each position is encoded as follows to reduce size: |
| // - 32-bit starting line number |
| // - 32-bit ending line number |
| // - (16 bit ending column number << 16) | (16-bit starting column number). |
| for i, block := range f.blocks { |
| start := f.fset.Position(block.startByte) |
| end := f.fset.Position(block.endByte) |
| fmt.Fprintf(w, "\t\t%d, %d, %#x, // [%d]\n", start.Line, end.Line, (end.Column&0xFFFF)<<16|(start.Column&0xFFFF), i) |
| } |
| |
| // Close the position array. |
| fmt.Fprintf(w, "\t},\n") |
| |
| // Initialize the position array field. |
| fmt.Fprintf(w, "\tNumStmt: [%d]uint16{\n", len(f.blocks)) |
| |
| // A nice long list of statements-per-block, so we can give a conventional |
| // valuation of "percent covered". To save space, it's a 16-bit number, so we |
| // clamp it if it overflows - won't matter in practice. |
| for i, block := range f.blocks { |
| n := block.numStmt |
| if n > 1<<16-1 { |
| n = 1<<16 - 1 |
| } |
| fmt.Fprintf(w, "\t\t%d, // %d\n", n, i) |
| } |
| |
| // Close the statements-per-block array. |
| fmt.Fprintf(w, "\t},\n") |
| |
| // Close the struct initialization. |
| fmt.Fprintf(w, "}\n") |
| } |