AssertionError when testing LocalDate with MockMvc and JUnit 5

I am trying to use JUnit 5 with Hibernate 5.4 and MockMvc in a Spring Boot 2.3 project.

This is how the members of my employee entity class looks like:

import java.time.LocalDate;
... (Rest of the imports)
@Entity
public class Employee {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Long employeeId;
@Column(nullable = false, updatable = true)
private String firstName;
@Column(nullable = true, updatable = true)
private String lastName;
@Column(nullable = false, updatable = true)
private String email;
@Column(nullable = false, updatable = true)
private LocalDate birthDate;

I am trying to test the LocalDate field birthDate with Mockito and MockMvc using JUnit 5. This is how the test case for that looks like:

	@Test
public void testFindEmployeeById() throws Exception {
Employee mockedEmployee = makeEmployee(9L, "Mock First", "Mock Last", "mock@email.com",
LocalDate.of(1996, 9, 8), 9L, "Mock Project", "Mock Department");
Mockito.when(employeeRepositoryMock.findById(mockedEmployee.getEmployeeId()))
.thenReturn(Optional.of(mockedEmployee));
mockMvc.perform(MockMvcRequestBuilders.get("/v1/employees/id/9").accept(MediaType.APPLICATION_JSON))
.andDo(MockMvcRestDocumentation.document("employeeById",
Preprocessors.preprocessRequest(Preprocessors.prettyPrint()),
PayloadDocumentation.responseFields(
PayloadDocumentation.fieldWithPath("employeeId").description("Employee ID"),
PayloadDocumentation.fieldWithPath("firstName").description("First Name"),
PayloadDocumentation.fieldWithPath("lastName").description("Last Name"),
PayloadDocumentation.fieldWithPath("email").description("Email Address"),
PayloadDocumentation.fieldWithPath("birthDate").description("Date of Birth"),
PayloadDocumentation.fieldWithPath("project.projectId").description("Project ID"),
PayloadDocumentation.fieldWithPath("project.name").description("Project name"),
PayloadDocumentation.fieldWithPath("project.department.departmentId")
.description("Department ID"),
PayloadDocumentation.fieldWithPath("project.department.name")
.description("Department Name"))))
.andDo(print()).andExpect(MockMvcResultMatchers.status().isOk())
.andExpect(MockMvcResultMatchers.jsonPath("$.employeeId").value(mockedEmployee.getEmployeeId()))
.andExpect(MockMvcResultMatchers.jsonPath("$.firstName").value(mockedEmployee.getFirstName()))
.andExpect(MockMvcResultMatchers.jsonPath("$.lastName").value(mockedEmployee.getLastName()))
.andExpect(MockMvcResultMatchers.jsonPath("$.email").value(mockedEmployee.getEmail()))
.andExpect(MockMvcResultMatchers.jsonPath("$.birthDate").value(mockedEmployee.getBirthDate()))
.andExpect(MockMvcResultMatchers.jsonPath("$.project.projectId")
.value(mockedEmployee.getProject().getProjectId()))
.andExpect(
MockMvcResultMatchers.jsonPath("$.project.name").value(mockedEmployee.getProject().getName()))
.andExpect(MockMvcResultMatchers.jsonPath("$.project.department.departmentId")
.value(mockedEmployee.getProject().getDepartment().getDepartmentId()))
.andExpect(MockMvcResultMatchers.jsonPath("$.project.department.name")
.value(mockedEmployee.getProject().getDepartment().getName()));
}

Upon running the test case, I get an AssertionError:

java.lang.AssertionError: JSON path "$.birthDate" expected:<1996-09-08> but was:<1996-09-08>

As you can tell, both the string representations are the same. Yet JUnit 5 throws the error.

So, what is the right way to go about comparing LocalDate with JUnit 5?

A similar question can be found here: https://stackoverflow.com/questions/61184154/comparing-localdate-using-hamcrest-in-junit-test-case
and here: https://stackoverflow.com/questions/45592405/junit-assertionerror-when-testing-simpledateformat

Thanks in advance.

JsonPath operates on actual JSON itself. By this time, your LocalDate has been converted to a JSON string value. While there's an argument that the matcher should automatically convert Java values to strings, it doesn't, but if you call localDate.toString(), then you it should work.

(More generally, any time you get a matcher error saying that two values that look identical don't match, it's probably because they're different types that have a common toString() format.)