unit-test-controller-layer

仓库: giuseppe-trisciuoglio/developer-kit
安装量: 330
排名: #2804

安装

npx skills add https://github.com/giuseppe-trisciuoglio/developer-kit --skill unit-test-controller-layer
Unit Testing REST Controllers with MockMvc
Overview
This skill provides patterns for unit testing @RestController and @Controller classes using MockMvc. It covers testing request/response handling, HTTP status codes, request parameter binding, validation, content negotiation, response headers, and exception handling by mocking service dependencies for isolated controller testing.
When to Use
Use this skill when:
Testing REST controller request/response handling
Verifying HTTP status codes and response formats
Testing request parameter binding and validation
Mocking service layer for isolated controller tests
Testing content negotiation and response headers
Want fast controller tests without integration test overhead
Instructions
Use standalone MockMvc setup
Use
MockMvcBuilders.standaloneSetup(controller)
for isolated testing
Mock all service dependencies
Use @Mock for all services injected into the controller
Test all HTTP methods
Verify GET, POST, PUT, PATCH, DELETE with appropriate status codes
Verify request/response formats
Use JsonPath assertions for JSON response validation
Test validation errors
Send invalid requests and verify 400 status with error details
Test error scenarios
Verify 404, 400, 401, 403, 500 status codes for appropriate conditions
Test headers
Verify both request headers (Authorization) and response headers
Use content negotiation
Test with different Accept and Content-Type headers
Examples
Setup: MockMvc + Mockito
Maven
<
dependency
>
<
groupId
>
org.springframework.boot
</
groupId
>
<
artifactId
>
spring-boot-starter-test
</
artifactId
>
<
scope
>
test
</
scope
>
</
dependency
>
<
dependency
>
<
groupId
>
org.mockito
</
groupId
>
<
artifactId
>
mockito-core
</
artifactId
>
<
scope
>
test
</
scope
>
</
dependency
>
Gradle
dependencies
{
testImplementation
(
"org.springframework.boot:spring-boot-starter-test"
)
testImplementation
(
"org.mockito:mockito-core"
)
}
Basic Pattern: Testing GET Endpoint
Simple GET Endpoint Test
import
org
.
junit
.
jupiter
.
api
.
Test
;
import
org
.
junit
.
jupiter
.
api
.
extension
.
ExtendWith
;
import
org
.
mockito
.
InjectMocks
;
import
org
.
mockito
.
Mock
;
import
org
.
mockito
.
junit
.
jupiter
.
MockitoExtension
;
import
org
.
springframework
.
test
.
web
.
servlet
.
MockMvc
;
import
org
.
springframework
.
test
.
web
.
servlet
.
setup
.
MockMvcBuilders
;
import
static
org
.
mockito
.
Mockito
.
*
;
import
static
org
.
springframework
.
test
.
web
.
servlet
.
request
.
MockMvcRequestBuilders
.
*
;
import
static
org
.
springframework
.
test
.
web
.
servlet
.
result
.
MockMvcResultMatchers
.
*
;
@ExtendWith
(
MockitoExtension
.
class
)
class
UserControllerTest
{
@Mock
private
UserService
userService
;
@InjectMocks
private
UserController
userController
;
private
MockMvc
mockMvc
;
void
setUp
(
)
{
mockMvc
=
MockMvcBuilders
.
standaloneSetup
(
userController
)
.
build
(
)
;
}
@Test
void
shouldReturnAllUsers
(
)
throws
Exception
{
List
<
UserDto
>
users
=
List
.
of
(
new
UserDto
(
1L
,
"Alice"
)
,
new
UserDto
(
2L
,
"Bob"
)
)
;
when
(
userService
.
getAllUsers
(
)
)
.
thenReturn
(
users
)
;
mockMvc
.
perform
(
get
(
"/api/users"
)
)
.
andExpect
(
status
(
)
.
isOk
(
)
)
.
andExpect
(
jsonPath
(
"$"
)
.
isArray
(
)
)
.
andExpect
(
jsonPath
(
"$[0].id"
)
.
value
(
1
)
)
.
andExpect
(
jsonPath
(
"$[0].name"
)
.
value
(
"Alice"
)
)
.
andExpect
(
jsonPath
(
"$[1].id"
)
.
value
(
2
)
)
;
verify
(
userService
,
times
(
1
)
)
.
getAllUsers
(
)
;
}
@Test
void
shouldReturnUserById
(
)
throws
Exception
{
UserDto
user
=
new
UserDto
(
1L
,
"Alice"
)
;
when
(
userService
.
getUserById
(
1L
)
)
.
thenReturn
(
user
)
;
mockMvc
.
perform
(
get
(
"/api/users/1"
)
)
.
andExpect
(
status
(
)
.
isOk
(
)
)
.
andExpect
(
jsonPath
(
"$.id"
)
.
value
(
1
)
)
.
andExpect
(
jsonPath
(
"$.name"
)
.
value
(
"Alice"
)
)
;
verify
(
userService
)
.
getUserById
(
1L
)
;
}
}
Testing POST Endpoint
Create Resource with Request Body
@Test
void
shouldCreateUserAndReturn201
(
)
throws
Exception
{
UserCreateRequest
request
=
new
UserCreateRequest
(
"Alice"
,
"alice@example.com"
)
;
UserDto
createdUser
=
new
UserDto
(
1L
,
"Alice"
,
"alice@example.com"
)
;
when
(
userService
.
createUser
(
any
(
UserCreateRequest
.
class
)
)
)
.
thenReturn
(
createdUser
)
;
mockMvc
.
perform
(
post
(
"/api/users"
)
.
contentType
(
"application/json"
)
.
content
(
"{\"name\":\"Alice\",\"email\":\"alice@example.com\"}"
)
)
.
andExpect
(
status
(
)
.
isCreated
(
)
)
.
andExpect
(
jsonPath
(
"$.id"
)
.
value
(
1
)
)
.
andExpect
(
jsonPath
(
"$.name"
)
.
value
(
"Alice"
)
)
.
andExpect
(
jsonPath
(
"$.email"
)
.
value
(
"alice@example.com"
)
)
;
verify
(
userService
)
.
createUser
(
any
(
UserCreateRequest
.
class
)
)
;
}
Testing Error Scenarios
Handle 404 Not Found
@Test
void
shouldReturn404WhenUserNotFound
(
)
throws
Exception
{
when
(
userService
.
getUserById
(
999L
)
)
.
thenThrow
(
new
UserNotFoundException
(
"User not found"
)
)
;
mockMvc
.
perform
(
get
(
"/api/users/999"
)
)
.
andExpect
(
status
(
)
.
isNotFound
(
)
)
.
andExpect
(
jsonPath
(
"$.error"
)
.
value
(
"User not found"
)
)
;
verify
(
userService
)
.
getUserById
(
999L
)
;
}
Handle 400 Bad Request
@Test
void
shouldReturn400WhenRequestBodyInvalid
(
)
throws
Exception
{
mockMvc
.
perform
(
post
(
"/api/users"
)
.
contentType
(
"application/json"
)
.
content
(
"{\"name\":\"\"}"
)
)
// Empty name
.
andExpect
(
status
(
)
.
isBadRequest
(
)
)
.
andExpect
(
jsonPath
(
"$.errors"
)
.
isArray
(
)
)
;
}
Testing PUT/PATCH Endpoints
Update Resource
@Test
void
shouldUpdateUserAndReturn200
(
)
throws
Exception
{
UserUpdateRequest
request
=
new
UserUpdateRequest
(
"Alice Updated"
)
;
UserDto
updatedUser
=
new
UserDto
(
1L
,
"Alice Updated"
)
;
when
(
userService
.
updateUser
(
eq
(
1L
)
,
any
(
UserUpdateRequest
.
class
)
)
)
.
thenReturn
(
updatedUser
)
;
mockMvc
.
perform
(
put
(
"/api/users/1"
)
.
contentType
(
"application/json"
)
.
content
(
"{\"name\":\"Alice Updated\"}"
)
)
.
andExpect
(
status
(
)
.
isOk
(
)
)
.
andExpect
(
jsonPath
(
"$.id"
)
.
value
(
1
)
)
.
andExpect
(
jsonPath
(
"$.name"
)
.
value
(
"Alice Updated"
)
)
;
verify
(
userService
)
.
updateUser
(
eq
(
1L
)
,
any
(
UserUpdateRequest
.
class
)
)
;
}
Testing DELETE Endpoint
Delete Resource
@Test
void
shouldDeleteUserAndReturn204
(
)
throws
Exception
{
doNothing
(
)
.
when
(
userService
)
.
deleteUser
(
1L
)
;
mockMvc
.
perform
(
delete
(
"/api/users/1"
)
)
.
andExpect
(
status
(
)
.
isNoContent
(
)
)
;
verify
(
userService
)
.
deleteUser
(
1L
)
;
}
@Test
void
shouldReturn404WhenDeletingNonExistentUser
(
)
throws
Exception
{
doThrow
(
new
UserNotFoundException
(
"User not found"
)
)
.
when
(
userService
)
.
deleteUser
(
999L
)
;
mockMvc
.
perform
(
delete
(
"/api/users/999"
)
)
.
andExpect
(
status
(
)
.
isNotFound
(
)
)
;
}
Testing Request Parameters
Query Parameters
@Test
void
shouldFilterUsersByName
(
)
throws
Exception
{
List
<
UserDto
>
users
=
List
.
of
(
new
UserDto
(
1L
,
"Alice"
)
)
;
when
(
userService
.
searchUsers
(
"Alice"
)
)
.
thenReturn
(
users
)
;
mockMvc
.
perform
(
get
(
"/api/users/search?name=Alice"
)
)
.
andExpect
(
status
(
)
.
isOk
(
)
)
.
andExpect
(
jsonPath
(
"$"
)
.
isArray
(
)
)
.
andExpect
(
jsonPath
(
"$[0].name"
)
.
value
(
"Alice"
)
)
;
verify
(
userService
)
.
searchUsers
(
"Alice"
)
;
}
Path Variables
@Test
void
shouldGetUserByIdFromPath
(
)
throws
Exception
{
UserDto
user
=
new
UserDto
(
123L
,
"Alice"
)
;
when
(
userService
.
getUserById
(
123L
)
)
.
thenReturn
(
user
)
;
mockMvc
.
perform
(
get
(
"/api/users/{id}"
,
123L
)
)
.
andExpect
(
status
(
)
.
isOk
(
)
)
.
andExpect
(
jsonPath
(
"$.id"
)
.
value
(
123
)
)
;
}
Testing Response Headers
Verify Response Headers
@Test
void
shouldReturnCustomHeaders
(
)
throws
Exception
{
when
(
userService
.
getAllUsers
(
)
)
.
thenReturn
(
List
.
of
(
)
)
;
mockMvc
.
perform
(
get
(
"/api/users"
)
)
.
andExpect
(
status
(
)
.
isOk
(
)
)
.
andExpect
(
header
(
)
.
exists
(
"X-Total-Count"
)
)
.
andExpect
(
header
(
)
.
string
(
"X-Total-Count"
,
"0"
)
)
.
andExpect
(
header
(
)
.
string
(
"Content-Type"
,
containsString
(
"application/json"
)
)
)
;
}
Testing Request Headers
Send Request Headers
@Test
void
shouldRequireAuthorizationHeader
(
)
throws
Exception
{
mockMvc
.
perform
(
get
(
"/api/users"
)
)
.
andExpect
(
status
(
)
.
isUnauthorized
(
)
)
;
mockMvc
.
perform
(
get
(
"/api/users"
)
.
header
(
"Authorization"
,
"Bearer token123"
)
)
.
andExpect
(
status
(
)
.
isOk
(
)
)
;
}
Content Negotiation
Test Different Accept Headers
@Test
void
shouldReturnJsonWhenAcceptHeaderIsJson
(
)
throws
Exception
{
UserDto
user
=
new
UserDto
(
1L
,
"Alice"
)
;
when
(
userService
.
getUserById
(
1L
)
)
.
thenReturn
(
user
)
;
mockMvc
.
perform
(
get
(
"/api/users/1"
)
.
accept
(
"application/json"
)
)
.
andExpect
(
status
(
)
.
isOk
(
)
)
.
andExpect
(
content
(
)
.
contentType
(
"application/json"
)
)
;
}
Advanced: Testing Multiple Status Codes
@Test
void
shouldReturnDifferentStatusCodesForDifferentScenarios
(
)
throws
Exception
{
// Successful response
when
(
userService
.
getUserById
(
1L
)
)
.
thenReturn
(
new
UserDto
(
1L
,
"Alice"
)
)
;
mockMvc
.
perform
(
get
(
"/api/users/1"
)
)
.
andExpect
(
status
(
)
.
isOk
(
)
)
;
// Not found
when
(
userService
.
getUserById
(
999L
)
)
.
thenThrow
(
new
UserNotFoundException
(
"Not found"
)
)
;
mockMvc
.
perform
(
get
(
"/api/users/999"
)
)
.
andExpect
(
status
(
)
.
isNotFound
(
)
)
;
// Unauthorized
mockMvc
.
perform
(
get
(
"/api/admin/users"
)
)
.
andExpect
(
status
(
)
.
isUnauthorized
(
)
)
;
}
Best Practices
Use standalone setup
when testing single controller:
MockMvcBuilders.standaloneSetup()
Mock service layer
- controllers should focus on HTTP handling
Test happy path and error paths
thoroughly
Verify service method calls
to ensure controller delegates correctly
Use content() matchers
for response body validation
Keep tests focused
on one endpoint behavior per test
Use JsonPath
for fluent JSON response assertions
Common Pitfalls
Testing business logic in controller
Move to service tests
Not mocking service layer
Always mock service dependencies
Testing framework behavior
Focus on your code, not Spring code
Hardcoding URLs
Use MockMvcRequestBuilders helpers
Not verifying mock interactions
Always verify service was called correctly
Constraints and Warnings
Controller tests are not integration tests
They verify HTTP handling, not full request flow
MockMvc standalone setup limitations
Some features like @Validated may not work without full context
JsonPath requires proper JSON structure
Ensure response body is valid JSON for JsonPath assertions
Don't test framework behavior
Spring's request mapping is tested by Spring; test your code only
Avoid hardcoding URLs
Extract URL paths to constants or use the controller's @RequestMapping values
Security annotations
@PreAuthorize and @Secured require additional setup; consider separate security tests
File uploads
Use MockMultipartFile for testing multipart file uploads
Troubleshooting
Content type mismatch
Ensure
contentType()
matches controller's
@PostMapping(consumes=...)
or use default.
JsonPath not matching
Use
mockMvc.perform(...).andDo(print())
to see actual response content.
Status code assertions fail
Check controller @RequestMapping , @PostMapping status codes and error handling. References Spring MockMvc Documentation JsonPath for REST Assertions Spring Testing Best Practices
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