fix(tdutil): testing.T.output needs some inits starting go1.25

Signed-off-by: Maxime Soulé <btik-git@scoubidou.com>

Author: maxatome

helpers/tdutil/t.go

@@ -14,8 +14,11 @@ package tdutil
 import (
 	"reflect"
 	"testing"
+	"unsafe"
 )
 
+var testingT = reflect.TypeOf(testing.T{})
+
 // T can be used in tests, to test [testing.T] behavior as it overrides
 // [testing.T.Run] method.
 type T struct {
@@ -28,7 +31,9 @@ type tFailedNow struct{}
 // NewT returns a new [*T] instance. name is the string returned by
 // method Name.
 func NewT(name string) *T {
-	return &T{name: name}
+	t := &T{name: name}
+	t.prepareForLogs()
+	return t
 }
 
 // Run is a simplified version of [testing.T.Run] method, without edge
@@ -70,6 +75,11 @@ func (t *T) Fatalf(format string, args ...any) {
 	t.FailNow()
 }
 
+// Starting go1.18, unsafe.Add can be used instead.
+func ptrAdd(p unsafe.Pointer, x uintptr) unsafe.Pointer {
+	return unsafe.Pointer(uintptr(p) + x)
+}
+
 // CatchFailNow returns true if a [T.FailNow], [T.Fatal] or [T.Fatalf] call
 // occurred during the execution of fn.
 func (t *T) CatchFailNow(fn func()) (failNowOccurred bool) {
@@ -85,3 +95,34 @@ func (t *T) CatchFailNow(fn func()) (failNowOccurred bool) {
 	fn()
 	return
 }
+
+func (t *T) prepareForLogs() {
+	if _, ok := testingT.FieldByName("output"); !ok {
+		panic("testing.T.output field not found!")
+	}
+
+	// o is a new go1.25 testing.common field
+	if o, ok := testingT.FieldByName("o"); ok {
+		ot := o.Type.Elem()
+
+		// With go1.25 t.T.o needs to be set to feed t.T.output
+		type outputWriter struct {
+			c       *testing.T
+			partial []byte //nolint: unused
+		}
+		owt := reflect.TypeOf(outputWriter{})
+
+		if ot.NumField() != owt.NumField() ||
+			ot.Field(0).Name != owt.Field(0).Name || // ot.c is *testing.common
+			ot.Field(1).Type != owt.Field(1).Type {
+			panic("testing.T.outputWriter changed")
+		}
+
+		// Use ptrAdd to support go1.16 & go1.17, but starting go1.18 we can use:
+		// oAddr := (**outputWriter)(unsafe.Add(unsafe.Pointer(&t.T), o.Offset))
+		oAddr := (**outputWriter)(ptrAdd(unsafe.Pointer(&t.T), o.Offset))
+		*oAddr = &outputWriter{
+			c: &t.T,
+		}
+	}
+}

td/types_test.go

@@ -19,7 +19,7 @@ import (
 func TestSetlocation(t *testing.T) {
 	//nolint: gocritic
 //line types_test.go:10
-	tt := &tdutil.T{}
+	tt := tdutil.NewT("test")
 	ok := td.Cmp(tt, 12, 13)
 	if !ok {
 		test.EqualStr(t, tt.LogBuf(), `    types_test.go:11: Failed test
@@ -33,7 +33,7 @@ func TestSetlocation(t *testing.T) {
 
 	//nolint: gocritic
 //line types_test.go:20
-	tt = &tdutil.T{}
+	tt = tdutil.NewT("test")
 	ok = td.Cmp(tt,
 		12,
 		td.Any(13, 14, 15))
@@ -52,7 +52,7 @@ func TestSetlocation(t *testing.T) {
 
 	//nolint: gocritic
 //line types_test.go:30
-	tt = &tdutil.T{}
+	tt = tdutil.NewT("test")
 	ok = td.CmpAny(tt,
 		12,
 		[]any{13, 14, 15})
@@ -70,7 +70,7 @@ func TestSetlocation(t *testing.T) {
 
 	//nolint: gocritic
 //line types_test.go:40
-	tt = &tdutil.T{}
+	tt = tdutil.NewT("test")
 	ttt := td.NewT(tt)
 	ok = ttt.Cmp(
 		12,
@@ -90,7 +90,7 @@ func TestSetlocation(t *testing.T) {
 
 	//nolint: gocritic
 //line types_test.go:50
-	tt = &tdutil.T{}
+	tt = tdutil.NewT("test")
 	ttt = td.NewT(tt)
 	ok = ttt.Any(
 		12,
@@ -108,7 +108,7 @@ func TestSetlocation(t *testing.T) {
 	}
 
 //line /a/full/path/types_test.go:50
-	tt = &tdutil.T{}
+	tt = tdutil.NewT("test")
 	ttt = td.NewT(tt)
 	ok = ttt.Any(
 		12,