feat(infra): implement zero-dependency pure in-memory cache plugin

backend/plugins/infra/cache_memory/plugin_test.go

@@ -0,0 +1,82 @@
+// Copyright 2026 Arctel.net
+// SPDX-License-Identifier: Apache-2.0
+
+package cache_memory_test
+
+import (
+	"context"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	"Wavelet/core"
+	"Wavelet/core/contracts"
+	"Wavelet/plugins/infra/cache_memory"
+)
+
+func TestCacheMemoryPlugin(t *testing.T) {
+	ctx := core.NewContext(context.Background())
+	p := cache_memory.New(cache_memory.WithCapacity(100))
+
+	assert.Equal(t, "cache_memory", p.Name())
+	assert.Equal(t, "1.0.0", p.Manifest().Version)
+	require.NoError(t, p.Apply(ctx))
+
+	cacheSvc, err := core.Inject[contracts.CacheService](ctx)
+	require.NoError(t, err)
+	require.NotNil(t, cacheSvc)
+
+	reqCtx := context.Background()
+
+	// 1. Get non-existent
+	var target string
+	err = cacheSvc.Get(reqCtx, "non_existent", &target)
+	assert.ErrorIs(t, err, contracts.ErrCacheMiss)
+
+	// 2. Set and Get
+	err = cacheSvc.Set(reqCtx, "user:100", "Alice", 10*time.Minute)
+	require.NoError(t, err)
+
+	var name string
+	err = cacheSvc.Get(reqCtx, "user:100", &name)
+	require.NoError(t, err)
+	assert.Equal(t, "Alice", name)
+
+	// 3. GetOrSet
+	var count int
+	var loaded int
+	loader := func() (any, error) {
+		loaded++
+		return 42, nil
+	}
+	err = cacheSvc.GetOrSet(reqCtx, "counter", &count, 10*time.Minute, loader)
+	require.NoError(t, err)
+	assert.Equal(t, 42, count)
+	assert.Equal(t, 1, loaded)
+
+	// Second GetOrSet hits cache
+	var count2 int
+	err = cacheSvc.GetOrSet(reqCtx, "counter", &count2, 10*time.Minute, loader)
+	require.NoError(t, err)
+	assert.Equal(t, 42, count2)
+	assert.Equal(t, 1, loaded)
+
+	// 4. Delete & Invalidate
+	require.NoError(t, cacheSvc.Delete(reqCtx, "user:100"))
+	err = cacheSvc.Get(reqCtx, "user:100", &name)
+	assert.ErrorIs(t, err, contracts.ErrCacheMiss)
+
+	require.NoError(t, cacheSvc.Invalidate(reqCtx, "counter"))
+	err = cacheSvc.Get(reqCtx, "counter", &count)
+	assert.ErrorIs(t, err, contracts.ErrCacheMiss)
+
+	// 5. Expiration
+	err = cacheSvc.Set(reqCtx, "temp_key", "val", 50*time.Millisecond)
+	require.NoError(t, err)
+	time.Sleep(70 * time.Millisecond)
+	var tempVal string
+	err = cacheSvc.Get(reqCtx, "temp_key", &tempVal)
+	assert.ErrorIs(t, err, contracts.ErrCacheMiss)
+}