Add test case for JacksonHandler. (#1353)

* test: Add test case for JacksonHandler.

* refactor: Set permission modifiers for JacksonHandlerTest's classes and methods.

---------

Co-authored-by: lucca <luccasuen.dev@gmail.com>

infra/common/src/test/java/cn/hippo4j/common/toolkit/JacksonHandlerTest.java

@@ -0,0 +1,140 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package cn.hippo4j.common.toolkit;
+
+import com.fasterxml.jackson.core.type.TypeReference;
+import com.fasterxml.jackson.databind.exc.MismatchedInputException;
+import lombok.AllArgsConstructor;
+import lombok.Data;
+import lombok.EqualsAndHashCode;
+import lombok.NoArgsConstructor;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+
+/**
+ * test for {@link JacksonHandler}
+ */
+public class JacksonHandlerTest {
+
+    private final static JacksonHandler JACKSON_HANDLER = new JacksonHandler();
+
+    private static final Entity EXPECTED_ENTITY =
+            new Entity(1, "entity1", new Entity(2, "entity2", null));
+
+    private static final List<Entity> EXPECTED_ENTITY_ARRAY = Arrays.asList(EXPECTED_ENTITY, EXPECTED_ENTITY);
+
+    private static final String EXPECTED_ENTITY_JSON = "{" +
+            "\"id\":1," +
+            "\"name\":\"entity1\"," +
+            "\"entity\":{" +
+            "\"id\":2," +
+            "\"name\":\"entity2\"" +
+            "}}";
+
+    private static final String EXPECTED_ENTITY_ARRAY_JSON = "[" +
+            EXPECTED_ENTITY_JSON + "," +
+            EXPECTED_ENTITY_JSON +
+            "]";
+
+    @Test
+    public void testToJSONString() {
+        // boolean to json
+        Assertions.assertEquals("true", JACKSON_HANDLER.toJSONString(true));
+        // double to json
+        Assertions.assertEquals("0.01", JACKSON_HANDLER.toJSONString(0.01));
+        // integer to json
+        Assertions.assertEquals("1", JACKSON_HANDLER.toJSONString(1));
+        // string to json
+        Assertions.assertEquals("\"hello world\"", JACKSON_HANDLER.toJSONString("hello world"));
+        // array to json
+        Assertions.assertEquals("[0,1,2,3,4]", JACKSON_HANDLER.toJSONString(new int[]{0, 1, 2, 3, 4}));
+        // object to json
+        Assertions.assertEquals(EXPECTED_ENTITY_JSON, JACKSON_HANDLER.toJSONString(EXPECTED_ENTITY));
+    }
+
+    @Test
+    public void testParseObject() {
+        // normal json to boolean
+        Assertions.assertEquals(true, JACKSON_HANDLER.parseObject("true", Boolean.class));
+        // normal json to double
+        Assertions.assertEquals(0.01, JACKSON_HANDLER.parseObject("0.01", Double.class));
+        // normal json to integer
+        Assertions.assertEquals(1, JACKSON_HANDLER.parseObject("1", Integer.class));
+        // normal json to string
+        Assertions.assertEquals("hello world",
+                JACKSON_HANDLER.parseObject("\"hello world\"", String.class));
+        // normal json to object
+        Assertions.assertEquals(EXPECTED_ENTITY, JACKSON_HANDLER.parseObject(EXPECTED_ENTITY_JSON, Entity.class));
+        Assertions.assertEquals(
+                EXPECTED_ENTITY,
+                JACKSON_HANDLER.parseObject(EXPECTED_ENTITY_JSON, new TypeReference<Entity>() {
+                })
+        );
+        // illegal json
+        Assertions.assertThrows(MismatchedInputException.class,
+                () -> JACKSON_HANDLER.parseObject(" ", Entity.class));
+        // null json
+        Assertions.assertThrows(IllegalArgumentException.class,
+                () -> JACKSON_HANDLER.parseObject(null, Entity.class));
+        // illegal type
+        Assertions.assertThrows(MismatchedInputException.class,
+                () -> JACKSON_HANDLER.parseObject(EXPECTED_ENTITY_JSON, String.class));
+    }
+
+    @Test
+    public void testParseArray() {
+        // normal json to array
+        Assertions.assertEquals(EXPECTED_ENTITY_ARRAY, JSONUtil.parseArray(EXPECTED_ENTITY_ARRAY_JSON, Entity.class));
+        // null json
+        Assertions.assertEquals(Collections.emptyList(), JSONUtil.parseArray(null, Entity.class));
+        // illegal json
+        Assertions.assertEquals(Collections.emptyList(), JSONUtil.parseArray(" ", Entity.class));
+    }
+
+    @Test
+    public void testIsJson() {
+        // normal json
+        Assertions.assertTrue(JACKSON_HANDLER.isJson(EXPECTED_ENTITY_JSON));
+        Assertions.assertTrue(JACKSON_HANDLER.isJson(EXPECTED_ENTITY_ARRAY_JSON));
+        Assertions.assertTrue(JACKSON_HANDLER.isJson(" "));
+        // illegal json
+        Assertions.assertFalse(JACKSON_HANDLER.isJson("{" +
+                "\"id\":1," +
+                "\"name\":\"entity1\"," +
+                "\"entity\":{\"id\":2,\"name\":\"entity2\"}"));
+        // null json
+        Assertions.assertThrows(IllegalArgumentException.class, () -> JACKSON_HANDLER.isJson(null));
+    }
+
+    @EqualsAndHashCode
+    @AllArgsConstructor
+    @NoArgsConstructor
+    @Data
+    private static class Entity {
+
+        private Integer id;
+
+        private String name;
+
+        private Entity entity;
+    }
+}