WIP

src/cleanup/cleanup.go

@@ -0,0 +1,28 @@
+package cleanup
+
+import "context"
+
+const ctxKey = "__cleanup"
+
+func Inject(ctx context.Context, foo func()) context.Context {
+	before := Extract(ctx)
+	after := func() {
+		foo()
+		before()
+	}
+	return context.WithValue(ctx, ctxKey, after)
+}
+
+func Extract(ctx context.Context) func() {
+	v := ctx.Value(ctxKey)
+	if v == nil {
+		return func() {}
+	}
+
+	v2, _ := v.(func())
+	if v2 == nil {
+		return func() {}
+	}
+
+	return v2
+}

src/cleanup/cleanup_test.go

@@ -0,0 +1,33 @@
+package cleanup_test
+
+import (
+	"context"
+	"show-rss/src/cleanup"
+	"testing"
+)
+
+func TestCleanup(t *testing.T) {
+	ctx := context.Background()
+
+	called := make([]bool, 100)
+	for i := range called {
+		i := i
+		ctx = cleanup.Inject(ctx, func() {
+			t.Logf("cleaning %d", i)
+			if i < len(called)-1 && !called[i+1] {
+				t.Errorf("cleaning %d before %d", i, i+1)
+			}
+			called[i] = true
+		})
+	}
+
+	t.Logf("cleaning")
+	cleanup.Extract(ctx)()
+	t.Logf("cleaned")
+
+	for i := range called {
+		if !called[i] {
+			t.Fatalf("missing called[%d]", i)
+		}
+	}
+}