codec_test.go

package rchan

import (
	"context"
	"errors"
	"fmt"
	"testing"
)

func TestJSONCodecRoundtrip(t *testing.T) {
	type point struct{ X, Y int }
	data, err := JSON.Marshal(point{1, 2})
	if err != nil {
		t.Fatal(err)
	}
	var p point
	if err := JSON.Unmarshal(data, &p); err != nil {
		t.Fatal(err)
	}
	if p != (point{1, 2}) {
		t.Fatalf("roundtrip got %+v", p)
	}
	if JSON.Name() != "json" {
		t.Fatalf("Name() = %q, want json", JSON.Name())
	}
}

type prefixCodec struct{}

func (prefixCodec) Marshal(v any) ([]byte, error) {
	b, err := JSON.Marshal(v)
	if err != nil {
		return nil, err
	}
	return append([]byte("x:"), b...), nil
}

func (prefixCodec) Unmarshal(d []byte, v any) error {
	if len(d) < 2 || d[0] != 'x' || d[1] != ':' {
		return fmt.Errorf("prefixCodec: bad frame")
	}
	return JSON.Unmarshal(d[2:], v)
}

func (prefixCodec) Name() string { return "prefix" }

func TestCustomCodecRoundtripAndMismatch(t *testing.T) {
	ctx := context.Background()
	rdb := testClient(t)
	name := testName(t, rdb)
	ch, err := New[string](ctx, rdb, name, WithCapacity(4), WithCodec(prefixCodec{}))
	if err != nil {
		t.Fatal(err)
	}
	defer ch.Stop()
	if err := ch.Send(ctx, "custom"); err != nil {
		t.Fatal(err)
	}
	v, ok, err := ch.Recv(ctx)
	if err != nil || !ok || v != "custom" {
		t.Fatalf("v=%q ok=%v err=%v", v, ok, err)
	}
	// Opening the same channel with a different codec must be rejected.
	if _, err := New[string](ctx, rdb, name, WithCapacity(4)); !errors.Is(err, ErrMismatch) {
		t.Fatalf("want ErrMismatch for codec change, got %v", err)
	}
}