tests: Add integer serialization/deserialization fuzzing harness

src/test/fuzz/integer.cpp

@@ -227,4 +227,44 @@ void test_one_input(const std::vector<uint8_t>& buffer)
         (void)HasAllDesirableServiceFlags(service_flags);
         (void)MayHaveUsefulAddressDB(service_flags);
     }
+
+    {
+        CDataStream stream(SER_NETWORK, INIT_PROTO_VERSION);
+
+        ser_writedata64(stream, u64);
+        const uint64_t deserialized_u64 = ser_readdata64(stream);
+        assert(u64 == deserialized_u64 && stream.empty());
+
+        ser_writedata32(stream, u32);
+        const uint32_t deserialized_u32 = ser_readdata32(stream);
+        assert(u32 == deserialized_u32 && stream.empty());
+
+        ser_writedata32be(stream, u32);
+        const uint32_t deserialized_u32be = ser_readdata32be(stream);
+        assert(u32 == deserialized_u32be && stream.empty());
+
+        ser_writedata16(stream, u16);
+        const uint16_t deserialized_u16 = ser_readdata16(stream);
+        assert(u16 == deserialized_u16 && stream.empty());
+
+        ser_writedata16be(stream, u16);
+        const uint16_t deserialized_u16be = ser_readdata16be(stream);
+        assert(u16 == deserialized_u16be && stream.empty());
+
+        ser_writedata8(stream, u8);
+        const uint8_t deserialized_u8 = ser_readdata8(stream);
+        assert(u8 == deserialized_u8 && stream.empty());
+    }
+
+    {
+        CDataStream stream(SER_NETWORK, INIT_PROTO_VERSION);
+
+        WriteCompactSize(stream, u64);
+        try {
+            const uint64_t deserialized_u64 = ReadCompactSize(stream);
+            assert(u64 == deserialized_u64 && stream.empty());
+        }
+        catch (const std::ios_base::failure&) {
+        }
+    }
 }