Support go 1.25

.github/workflows/CI.yml

@@ -10,7 +10,7 @@ jobs:
   CI:
     strategy:
       matrix:
-        go-version: [ "1.24.0" ]
+        go-version: [ "1.24.0", "1.25.0" ]
       fail-fast: true
     runs-on: ubuntu-latest
     steps:
@@ -26,4 +26,4 @@ jobs:
 
     - name: Upload coverage
       uses: coverallsapp/github-action@v2
-      if: ${{ contains(matrix.go-version, '1.24.0') }}
+      if: ${{ contains(matrix.go-version, '1.25.0') }}

fixture.go

@@ -6,6 +6,8 @@ import (
 	"unsafe"
 )
 
+var ctxOffset int
+
 type Fixture[V any] interface {
 	Value(t *testing.T) V
 }
@@ -26,7 +28,7 @@ func (f *fixture[V]) Value(t *testing.T) V {
 	value := f.createValue(t)
 
 	// Look away
-	ctx := (*context.Context)(unsafe.Add(unsafe.Pointer(t), 400))
+	ctx := (*context.Context)(unsafe.Add(unsafe.Pointer(t), ctxOffset))
 	*ctx = context.WithValue(t.Context(), f, value)
 
 	return value

version_1_24.go

@@ -0,0 +1,7 @@
+//go:build go1.24
+
+package fix
+
+func init() {
+	ctxOffset = 400
+}

version_1_25.go

@@ -0,0 +1,7 @@
+//go:build go1.25
+
+package fix
+
+func init() {
+	ctxOffset = 408
+}