feat(cache): 值编解码器(fastjson 序列化 + 空值标记)

src/test/java/com/njcn/middle/cache/support/CacheValueCodecTest.java

@@ -0,0 +1,64 @@
+package com.njcn.middle.cache.support;
+
+import com.alibaba.fastjson.TypeReference;
+import com.njcn.middle.cache.constant.CacheConstant;
+import lombok.AllArgsConstructor;
+import lombok.Data;
+import lombok.NoArgsConstructor;
+import org.junit.jupiter.api.Test;
+
+import java.util.Arrays;
+import java.util.List;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+class CacheValueCodecTest {
+
+    private final CacheValueCodec codec = new CacheValueCodec();
+
+    @Data
+    @AllArgsConstructor
+    @NoArgsConstructor
+    static class Foo {
+        private Long id;
+        private String name;
+    }
+
+    @Test
+    void encodeNullReturnsSentinel() {
+        assertEquals(CacheConstant.NULL_SENTINEL, codec.encode(null));
+        assertTrue(codec.isNullSentinel(codec.encode(null)));
+        assertFalse(codec.isNullSentinel("{\"id\":1}"));
+    }
+
+    @Test
+    void encodeDecodePojoRoundTrip() {
+        Foo foo = new Foo(1L, "alice");
+        String raw = codec.encode(foo);
+        Foo back = codec.decode(raw, Foo.class);
+        assertEquals(foo, back);
+    }
+
+    @Test
+    void encodeDecodeStringRoundTrip() {
+        String raw = codec.encode("abc");
+        assertEquals("abc", codec.decode(raw, String.class));
+    }
+
+    @Test
+    void decodeGenericWithTypeReference() {
+        List<Integer> list = Arrays.asList(1, 2, 3);
+        String raw = codec.encode(list);
+        List<Integer> back = codec.decode(raw, new TypeReference<List<Integer>>() {
+        });
+        assertEquals(list, back);
+    }
+
+    @Test
+    void decodeDirtyStringThrows() {
+        assertThrows(RuntimeException.class, () -> codec.decode("{not-json", Foo.class));
+    }
+}