memory_internal_test.go

package wal

import (
	"context"
	"errors"
	"math"
	"testing"
)

// Position exhaustion requires direct counter control and belongs to the
// implementation-invariant suite rather than the public black-box tests.
func TestMemoryWALRejectsPositionCounterOverflow(t *testing.T) {
	t.Parallel()

	log := newTestMemoryWAL(t)
	log.next = Position(math.MaxUint64)
	next := log.next

	if _, err := log.Append(
		context.Background(),
		Record{ID: "one"},
		Volatile,
	); !errors.Is(err, ErrCapacity) {
		t.Fatalf("Append overflow = %v", err)
	}

	if log.next != next ||
		len(log.entries) != 0 ||
		len(log.live) != 0 ||
		log.usedBytes != 0 {
		t.Fatal("Append overflow mutated the WAL")
	}

	log.next = Position(math.MaxUint64 - 1)

	next = log.next
	if _, err := log.AppendBatch(
		context.Background(),
		[]Record{{ID: "one"}, {ID: "two"}},
		Volatile,
	); !errors.Is(err, ErrCapacity) {
		t.Fatalf("AppendBatch overflow = %v", err)
	}

	if log.next != next ||
		len(log.entries) != 0 ||
		len(log.live) != 0 ||
		log.usedBytes != 0 {
		t.Fatal("AppendBatch overflow mutated the WAL")
	}
}

func newTestMemoryWAL(t *testing.T) *Memory {
	t.Helper()

	log, err := NewMemory(MemoryConfig{
		MaxBytes:       1 << 20,
		MaxRecords:     128,
		MaxRecordBytes: 1 << 16,
	})
	if err != nil {
		t.Fatal(err)
	}

	return log
}