runtime/debug: new package

Facilities for printing stack traces from within a running goroutine.

R=rsc
CC=golang-dev
https://golang.org/cl/4031041

src/pkg/runtime/debug/stack_test.go

@@ -0,0 +1,55 @@
+// Copyright 2011 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 debug
+
+import (
+	"strings"
+	"testing"
+)
+
+type T int
+
+func (t *T) ptrmethod() []byte {
+	return Stack()
+}
+func (t T) method() []byte {
+	return t.ptrmethod()
+}
+
+/*
+	The traceback should look something like this, modulo line numbers and hex constants.
+	Don't worry much about the base levels, but check the ones in our own package.
+
+		/Users/r/go/src/pkg/runtime/debug/stack_test.go:15 (0x13878)
+			*T.ptrmethod: return Stack()
+		/Users/r/go/src/pkg/runtime/debug/stack_test.go:18 (0x138dd)
+			T.method: return t.ptrmethod()
+		/Users/r/go/src/pkg/runtime/debug/stack_test.go:23 (0x13920)
+			TestStack: b := T(0).method()
+		/Users/r/go/src/pkg/testing/testing.go:132 (0x14a7a)
+			tRunner: test.F(t)
+		/Users/r/go/src/pkg/runtime/proc.c:145 (0xc970)
+			???: runtime·unlock(&runtime·sched);
+*/
+func TestStack(t *testing.T) {
+	b := T(0).method()
+	lines := strings.Split(string(b), "\n", -1)
+	if len(lines) <= 6 {
+		t.Fatal("too few lines")
+	}
+	check(t, lines[0], "src/pkg/runtime/debug/stack_test.go")
+	check(t, lines[1], "\t*T.ptrmethod: return Stack()")
+	check(t, lines[2], "src/pkg/runtime/debug/stack_test.go")
+	check(t, lines[3], "\tT.method: return t.ptrmethod()")
+	check(t, lines[4], "src/pkg/runtime/debug/stack_test.go")
+	check(t, lines[5], "\tTestStack: b := T(0).method()")
+	check(t, lines[6], "src/pkg/testing/testing.go")
+}
+
+func check(t *testing.T, line, has string) {
+	if strings.Index(line, has) < 0 {
+		t.Errorf("expected %q in %q", has, line)
+	}
+}