Add implementations of fmt.Stringer to stack.Call and stack.CallStack.

Author: ChrisHines

stack.go

@@ -45,6 +45,11 @@ func Caller(skip int) Call {
 	return c
 }
 
+// String implements fmt.Stinger. It is equivalent to fmt.Sprintf("%v", c).
+func (c Call) String() string {
+	return fmt.Sprint(c)
+}
+
 // Format implements fmt.Formatter with support for the following verbs.
 //
 //    %s    source file
@@ -171,6 +176,11 @@ func (c Call) line() int {
 // stack.
 type CallStack []Call
 
+// String implements fmt.Stinger. It is equivalent to fmt.Sprintf("%v", cs).
+func (cs CallStack) String() string {
+	return fmt.Sprint(cs)
+}
+
 // Format implements fmt.Formatter by printing the CallStack as square brackes
 // ([, ]) surrounding a space separated list of Calls each formatted with the
 // supplied verb and options.
@@ -268,12 +278,12 @@ func inGoroot(c Call) bool {
 	if runtime.GOOS == "windows" {
 		file = strings.ToLower(file)
 	}
-	return strings.HasPrefix(file, goroot)
+	return strings.HasPrefix(file, goroot) || strings.HasSuffix(file, "/_testmain.go")
 }
 
 // TrimRuntime returns a slice of the CallStack with the topmost entries from
 // the go runtime removed. It considers any calls originating from unknown
-// files or files under GOROOT as part of the runtime.
+// files, files under GOROOT, or _testmain.go as part of the runtime.
 func (cs CallStack) TrimRuntime() CallStack {
 	for len(cs) > 0 && inGoroot(cs[len(cs)-1]) {
 		cs = cs[:len(cs)-1]

stack_test.go

@@ -77,6 +77,62 @@ func TestCallFormat(t *testing.T) {
 	}
 }
 
+func TestCallString(t *testing.T) {
+	t.Parallel()
+
+	c := stack.Caller(0)
+	_, file, line, ok := runtime.Caller(0)
+	line--
+	if !ok {
+		t.Fatal("runtime.Caller(0) failed")
+	}
+
+	c2, _, file2, line2, ok2 := testType{}.testMethod()
+	if !ok2 {
+		t.Fatal("runtime.Caller(0) failed")
+	}
+
+	data := []struct {
+		c    stack.Call
+		desc string
+		out  string
+	}{
+		{stack.Call{}, "error", "%!v(NOFUNC)"},
+		{c, "func", fmt.Sprint(path.Base(file), ":", line)},
+		{c2, "meth", fmt.Sprint(path.Base(file2), ":", line2)},
+	}
+
+	for _, d := range data {
+		got := d.c.String()
+		if got != d.out {
+			t.Errorf("got %s, want %s", got, d.out)
+		}
+	}
+}
+
+func TestCallStackString(t *testing.T) {
+	cs, line0 := getTrace(t)
+	_, file, line1, ok := runtime.Caller(0)
+	line1--
+	if !ok {
+		t.Fatal("runtime.Caller(0) failed")
+	}
+	file = path.Base(file)
+	if got, want := cs.String(), fmt.Sprintf("[%s:%d %s:%d]", file, line0, file, line1); got != want {
+		t.Errorf("\n got %v\nwant %v", got, want)
+	}
+}
+
+func getTrace(t *testing.T) (stack.CallStack, int) {
+	cs := stack.Trace().TrimRuntime()
+	_, _, line, ok := runtime.Caller(0)
+	line--
+	if !ok {
+		t.Fatal("runtime.Caller(0) failed")
+	}
+	return cs, line
+}
+
 func TestTrimAbove(t *testing.T) {
 	trace := trimAbove()
 	if got, want := len(trace), 2; got != want {