Merge pull request #129 from maxatome/trace

feat(trace): when an error occurs, display trace if level > 1

internal/location/location.go

@@ -12,13 +12,13 @@ import (
 	"strings"
 )
 
-// Location record a place in a source file.
+// Location records a place in a source file.
 type Location struct {
 	File      string // File name
 	Func      string // Function name
 	Line      int    // Line number inside file
-	Inside    string
-	BehindCmp bool // BehindCmp is true when operator is behind a Cmp* function
+	Inside    string // Inside is used when Location is inside something else
+	BehindCmp bool   // BehindCmp is true when operator is behind a Cmp* function
 }
 
 // GetLocationer is the interface that wraps the basic GetLocation method.

internal/trace/trace.go

@@ -0,0 +1,235 @@
+// Copyright (c) 2021, Maxime Soulé
+// All rights reserved.
+//
+// This source code is licensed under the BSD-style license found in the
+// LICENSE file in the root directory of this source tree.
+
+package trace
+
+import (
+	"fmt"
+	"go/build"
+	"os"
+	"path/filepath"
+	"runtime"
+	"strings"
+)
+
+var (
+	ignorePkg = map[string]struct{}{}
+	goPaths   []string
+	goModDir  string
+)
+
+// Level represents a level when retrieving a trace.
+type Level struct {
+	Func     string
+	FileLine string
+}
+
+func getPackage(skip ...int) string {
+	sk := 2
+	if len(skip) > 0 {
+		sk += skip[0]
+	}
+	pc, _, _, ok := runtime.Caller(sk)
+	if ok {
+		fn := runtime.FuncForPC(pc)
+		if fn != nil {
+			pkg, _ := SplitPackageFunc(fn.Name())
+			return pkg
+		}
+	}
+	return ""
+}
+
+// IgnorePackage records the calling package as ignored one in trace.
+func IgnorePackage(skip ...int) bool {
+	if pkg := getPackage(skip...); pkg != "" {
+		ignorePkg[pkg] = struct{}{}
+		return true
+	}
+	return false
+}
+
+// UnignorePackage cancels a previous use of IgnorePackage, so the
+// calling package is no longer ignored. Only intended to be used in
+// go-testdeep internal tests.
+func UnignorePackage(skip ...int) bool {
+	if pkg := getPackage(skip...); pkg != "" {
+		delete(ignorePkg, pkg)
+		return true
+	}
+	return false
+}
+
+// IsIgnoredPackage returns true if pkg is ignored, false
+// otherwise. Only intended to be used in go-testdeep internal tests.
+func IsIgnoredPackage(pkg string) (ok bool) {
+	_, ok = ignorePkg[pkg]
+	return
+}
+
+// FindGoModDir finds the closest directory containing go.mod file
+// starting from directory in.
+func FindGoModDir(in string) string {
+	for {
+		_, err := os.Stat(filepath.Join(in, "go.mod"))
+		if err == nil {
+			// Do not accept /tmp/go.mod
+			if in != os.TempDir() {
+				return in + string(filepath.Separator)
+			}
+			return ""
+		}
+
+		nd := filepath.Dir(in)
+		if nd == in {
+			return ""
+		}
+		in = nd
+	}
+}
+
+// FindGoModDirLinks finds the closest directory containing go.mod
+// file starting from directory in after cleaning it. If not found,
+// expands symlinks and re-searches.
+func FindGoModDirLinks(in string) string {
+	in = filepath.Clean(in)
+
+	if gm := FindGoModDir(in); gm != "" {
+		return gm
+	}
+
+	lin, err := filepath.EvalSymlinks(in)
+	if err == nil && lin != in {
+		return FindGoModDir(lin)
+	}
+	return ""
+}
+
+// Reset resets the ignored packages map plus cached mod and GOPATH
+// directories (Init() should be called again). Only intended to be
+// used in go-testdeep internal tests.
+func Reset() {
+	ignorePkg = map[string]struct{}{}
+	goPaths = nil
+	goModDir = ""
+}
+
+// Init initializes trace global variables.
+func Init() {
+	// GOPATH directories
+	goPaths = nil
+	for _, dir := range filepath.SplitList(build.Default.GOPATH) {
+		dir = filepath.Clean(dir)
+		goPaths = append(goPaths,
+			filepath.Join(dir, "pkg", "mod")+string(filepath.Separator),
+			filepath.Join(dir, "src")+string(filepath.Separator),
+		)
+	}
+
+	if wd, err := os.Getwd(); err == nil {
+		// go.mod directory
+		goModDir = FindGoModDirLinks(wd)
+	}
+}
+
+// Frames is the interface corresponding to type returned by
+// runtime.CallersFrames. See CallersFrames variable.
+type Frames interface {
+	Next() (frame runtime.Frame, more bool)
+}
+
+// CallersFrames is only intended to be used in go-testdeep internal
+// tests to cover all cases.
+var CallersFrames = func(callers []uintptr) Frames {
+	return runtime.CallersFrames(callers)
+}
+
+// Retrieve retrieves a trace and returns it.
+func Retrieve(skip int, endFunction string) []Level {
+	var trace []Level
+	var pc [40]uintptr
+	if num := runtime.Callers(skip+2, pc[:]); num > 0 {
+		checkIgnore := true
+		frames := CallersFrames(pc[:num])
+		for {
+			frame, more := frames.Next()
+
+			fn := frame.Function
+			if fn == endFunction {
+				break
+			}
+
+			var pkg string
+			if fn == "" {
+				if frame.File == "" {
+					if more {
+						continue
+					}
+					break
+				}
+				fn = "<unknown function>"
+			} else {
+				pkg, fn = SplitPackageFunc(fn)
+				if checkIgnore && IsIgnoredPackage(pkg) {
+					if more {
+						continue
+					}
+					break
+				}
+				checkIgnore = false
+			}
+
+			file := strings.TrimPrefix(frame.File, goModDir)
+			if file == frame.File {
+				for _, dir := range goPaths {
+					file = strings.TrimPrefix(frame.File, dir)
+					if file != frame.File {
+						break
+					}
+				}
+
+				if file == frame.File {
+					file = strings.TrimPrefix(frame.File, build.Default.GOROOT)
+					if file != frame.File {
+						file = filepath.Join("$GOROOT", file)
+					}
+				}
+			}
+
+			level := Level{Func: fn}
+			if file != "" {
+				level.FileLine = fmt.Sprintf("%s:%d", file, frame.Line)
+			}
+
+			trace = append(trace, level)
+			if !more {
+				break
+			}
+		}
+	}
+	return trace
+}
+
+// SplitPackageFunc splits a fully qualified function name into its
+// package and function parts:
+//   "foo/bar/test.fn"            → "foo/bar/test", "fn"
+//   "foo/bar/test.X.fn"          → "foo/bar/test", "X.fn"
+//   "foo/bar/test.(*X).fn"       → "foo/bar/test", "(*X).fn"
+//   "foo/bar/test.(*X).fn.func1" → "foo/bar/test", "(*X).fn.func1"
+//   "weird"                      → "", "weird"
+func SplitPackageFunc(fn string) (string, string) {
+	sp := strings.LastIndexByte(fn, '/')
+	if sp < 0 {
+		sp = 0 // std package
+	}
+
+	dp := strings.IndexByte(fn[sp:], '.')
+	if dp < 0 {
+		return "", fn
+	}
+
+	return fn[:sp+dp], fn[sp+dp+1:]
+}