TestTraits.java

package com.mugil.org;

import com.google.gson.Gson;
import com.mugil.org.models.Employee;
import org.springframework.core.io.ClassPathResource;

import java.io.FileReader;
import java.io.IOException;
import java.io.Reader;

public interface TestTraits {
    public static Object getObjfromJson(String fileLoctaion) throws IOException {
        Gson gson = new Gson();
        Employee objEmployee2 = gson.fromJson(getReader(fileLoctaion), Employee.class);
        return objEmployee2;
    }

    public static Reader getReader(String fileLoctaion) throws IOException {
        return new FileReader(new ClassPathResource(fileLoctaion).getFile());
    }
}

EmployeeObject.json

{
  "empID": 101,
  "empName": "Mani",
  "empAge": "35"
}

EmployeeControllerTest.java
Read JSON Value as from File and Convert to Employee Object and to JSON String

JSON Value from File -> Employee Object -> JSON String from Object

  @Test
    void addEmployeeDetails() throws Exception {
        
        //Read values from JSON  
        Employee objEmployee = (Employee) TestTraits.getObjfromJson("json-data/EmployeeObject.json");

        //Convert Object to JSON String
        String jsonRequestString = mapper.writeValueAsString(objEmployee);

        when(employeeServiceImpl.saveEmployee(any())).thenReturn("101");

        ResultActions objResultActions = this.mockMvc.perform(post("/empmgmt/employees")
                .contentType(MediaType.APPLICATION_JSON)
                .content(jsonRequestString))
                .andDo(print())
                .andExpect(jsonPath("$.empID", is(Matchers.notNullValue())))
                .andExpect(jsonPath("$.empID", is(101)))
                .andExpect(jsonPath("$.empName", is("Mani")))
                .andExpect(status().isCreated());
    }

EmployeeControllerTest.java
Read JSON Value as from File and Convert to Employee Object and to JSON String

JSON Value from File -> Employee Object for Mocking Service Call

@Test
    void getEmployeeDetails() throws Exception {
          
        //Object Construction by reading file
        Employee objEmployee = (Employee) TestTraits.getObjfromJson("json-data/EmployeeObject.json");

        //Making object as Optional
        Optional<Employee> objEmp = Optional.ofNullable(objEmployee);

        //Mocked service response from object created
        when(employeeServiceImpl.findEmployee(EMP_ID)).thenReturn(objEmp);

        ResultActions objResultActions = this.mockMvc.perform(get("/empmgmt/employees/{empID}",EMP_ID))
                                                    .andDo(print())
                                                    .andExpect(jsonPath("$.empID", is(101)))
                                                    .andExpect(jsonPath("$.empName", is("Mani")))
                                                    .andExpect(jsonPath("$._links.all-employees.href", is("http://localhost/empmgmt/employees")))
                                                    .andExpect(status().isOk());
    }

Repo Link
https://bitbucket.org/Mugil/restwithspringboot/branch/feature/7MockMVCTesting_3