DZone
Thanks for visiting DZone today,
Edit Profile
  • Manage Email Subscriptions
  • How to Post to DZone
  • Article Submission Guidelines
Sign Out View Profile
  • Post an Article
  • Manage My Drafts
Over 2 million developers have joined DZone.
Log In / Join
Refcards Trend Reports Events Over 2 million developers have joined DZone. Join Today! Thanks for visiting DZone today,
Edit Profile Manage Email Subscriptions Moderation Admin Console How to Post to DZone Article Submission Guidelines
View Profile
Sign Out
Refcards
Trend Reports
Events
Zones
Culture and Methodologies Agile Career Development Methodologies Team Management
Data Engineering AI/ML Big Data Data Databases IoT
Software Design and Architecture Cloud Architecture Containers Integration Microservices Performance Security
Coding Frameworks Java JavaScript Languages Tools
Testing, Deployment, and Maintenance Deployment DevOps and CI/CD Maintenance Monitoring and Observability Testing, Tools, and Frameworks
Partner Zones AWS Cloud
by AWS Developer Relations
Culture and Methodologies
Agile Career Development Methodologies Team Management
Data Engineering
AI/ML Big Data Data Databases IoT
Software Design and Architecture
Cloud Architecture Containers Integration Microservices Performance Security
Coding
Frameworks Java JavaScript Languages Tools
Testing, Deployment, and Maintenance
Deployment DevOps and CI/CD Maintenance Monitoring and Observability Testing, Tools, and Frameworks
Partner Zones
AWS Cloud
by AWS Developer Relations
Building Scalable Real-Time Apps with AstraDB and Vaadin
Register Now

Trending

  • Managing Data Residency, the Demo
  • Why You Should Consider Using React Router V6: An Overview of Changes
  • What Is React? A Complete Guide
  • Authorization: Get It Done Right, Get It Done Early

Trending

  • Managing Data Residency, the Demo
  • Why You Should Consider Using React Router V6: An Overview of Changes
  • What Is React? A Complete Guide
  • Authorization: Get It Done Right, Get It Done Early
  1. DZone
  2. Coding
  3. Languages
  4. Kotlin Wiremock

Kotlin Wiremock

Here's a handy Kotline library for stubbing WireMock expectations.

Marcin Zioło user avatar by
Marcin Zioło
·
Jul. 28, 20 · Tutorial
Like (4)
Save
Tweet
Share
9.40K Views

Join the DZone community and get the full member experience.

Join For Free

WireMock is a popular library for stubbing web services. It runs an HTTP server that acts as an actual web service. We just set up expectations and run the server.

In this tutorial, we will present the kotlin-wiremock library that provides a nice domain-specific language for stubbing WireMock expectations.

Getting Started

The first step is adding dependencies. 

Maven

XML
 




xxxxxxxxxx
1


 
1
<dependency>
2
    <groupId>com.marcinziolo</groupId>
3
    <artifactId>kotlin-wiremock</artifactId>
4
    <version>1.0.0</version>
5
    <scope>test</scope>
6
</dependency>


Gradle

Kotlin
 




xxxxxxxxxx
1


 
1
testImplementation("com.marcinziolo:kotlin-wiremock:version")



And now we can use kotlin-wiremock. Let's see the JUnit 4 example.

Kotlin
 




xxxxxxxxxx
1
49


 
1
import com.github.tomakehurst.wiremock.junit.WireMockRule
2
import io.restassured.module.kotlin.extensions.Then
3
import io.restassured.module.kotlin.extensions.When
4
import org.hamcrest.Matchers.equalTo
5
import org.junit.Rule
6
import org.junit.Test
7
import java.net.ServerSocket
8

          
9
class JUnit4ExampleTest {
10

          
11
    val port = findRandomPort()
12

          
13
    val url = "http://localhost:$port"
14

          
15
    @Rule
16
    @JvmField
17
    var wiremock: WireMockRule = WireMockRule(port)
18

          
19
    @Test
20
    fun `url matching`() {
21
        wiremock.get {
22
            url like  "/users/.*"
23
        } returns  {
24
            header = "Content-Type" to "application/json"
25
            statusCode = 200
26
            body = """
27
            {
28
              "id": 1,
29
              "name": "Bob"
30
            }
31
            """
32
        }
33
        assertBobSuccess()
34
    }
35

          
36
    private fun assertBobSuccess() {
37
        When {
38
            get("$url/users/1")
39
        } Then {
40
            statusCode(200)
41
            body("id", equalTo(1))
42
            body("name", equalTo("Bob"))
43
        }
44
    }
45

          
46
    fun findRandomPort(): Int {
47
        ServerSocket(0).use { socket -> return socket.localPort }
48
    }
49
}


Features

One of the basic features is url matching.  Let's see an example: when calling a server with URL equal /users/1, the server returns a JSON body with Bob's response.

Kotlin
 




x





1
wiremock.get {
2
  url equalTo "/users/1"
3
} returns {
4
  header = "Content-Type" to "application/json"
5
  statusCode = 200
6
  body = """{"id": 1,"name": "Bob"}"""
7
}



We can also use regular expressions for matching url. Notice that we can use method returnsJson so we don't need to specify the Conte-Type header manually.

Kotlin
 




xxxxxxxxxx
1


 
1
wiremock.get {
2
  url like "/users/.*"
3
} returnsJson {
4
  body = """{"id": 1,"name": "Bob"}"""
5
}



Let's see how we can stub the post request. We return bobResponse only when request JSON body fulfills the following criteria:

  • id key equalTo 1
  • isAdmin key equalTo true
  • points equalTo 3.0
  • data object contains name key which starts with Bob string.

As you can see we have a full spectrum of solutions for mathing the request body. Note that the library gives us the possibility to check value types(string, integer, float, boolean). 

Kotlin
 




xxxxxxxxxx
1


 
1
val bobResponse: SpecifyResponse = { body = """{"id": 1,"name": "Bob"}""" }
2
wiremock.post {
3
  url equalTo "/users"
4
    body contains "id" equalTo 1
5
    body contains "isAdmin" equalTo true
6
    body contains "points" equalTo 3.0
7
    body contains "data.name" like "Bob.*"
8
} returnsJson bobResponse



We can also check headers and query params:

Kotlin
 




xxxxxxxxxx
1


 
1
wiremock.post {
2
    headers contains "User-Agent" like "Firefox.*"
3
    queryParams contains "page" equalTo "1" 
4
}



Look how priorities work, when we send Authorization header then the response is 200 otherwise the server replies with 403.

Kotlin
 




xxxxxxxxxx
1
14


 
1
wiremock.post {
2
    url equalTo "/test"
3
    priority = 2
4
} returnsJson  {
5
    statusCode = 403
6
}
7

          
8
wiremock.post {
9
    url equalTo "/test"
10
    headers contains "Authorization"
11
    priority = 1
12
} returnsJson  {
13
    statusCode = 200
14
}



We can even simulate delays.

Kotlin
 




xxxxxxxxxx
1


 
1
wiremock.post {
2
    url equalTo "/users"
3
} returnsJson {
4
    delay fixedMs 100
5
    //or gaussian distribution
6
    delay medianMs 100 sigma 0.1
7
}    



We can come up with more sophisticated scenarios. The first request returns bobResponse but we set flag toState to Alice. So the second response returns aliceResponse,

Java
 




xxxxxxxxxx
1
12


 
1
wiremock.post {
2
     url equalTo "/users"
3
 } returnsJson bobResponse and {
4
     toState = "Alice"
5
 }
6

          
7
 wiremock.post {
8
     url equalTo "/users"
9
     whenState = "Alice"
10
 } returnsJson aliceResponse and {
11
     clearState = true
12
 }



Summary

All features presented in this tutorial can be achieved via wireMock API.

Java
 




x
10
9


 
1
stubFor(any(urlPathEqualTo("/everything"))
2
  .withHeader("Accept", containing("json"))
3
  .withQueryParam("search_term", equalTo("WireMock"))
4
  .withRequestBody(matchingJsonPath("$.things[?(@.name =~ /Required.*/i')]"))
5
  .willReturn(aResponse()
6
              .withHeader("Content-Type", "text/plain")
7
              .withBody("Hello world!")));



But doesn't it look way better in Kotlin Wiremock DSL?

Kotlin
 




xxxxxxxxxx
1


 
1
wiremock.get {
2
  url equalTo "/everything"
3
  header contains "Accept" contains "json"
4
  queryParams contains "search_term" equalTo "WireMock"
5
  body contains "things.name" like "Required.*"
6
} returns {
7
  header = "Content-Type" to "text/plain"
8
  body = "Hello world"
9
}



More examples can be found here:

  • Miscellaneous examples
  • JUnit4 example
  • JUnit5 base class
Kotlin (programming language)

Opinions expressed by DZone contributors are their own.

Trending

  • Managing Data Residency, the Demo
  • Why You Should Consider Using React Router V6: An Overview of Changes
  • What Is React? A Complete Guide
  • Authorization: Get It Done Right, Get It Done Early

Comments

Partner Resources

X

ABOUT US

  • About DZone
  • Send feedback
  • Careers
  • Sitemap

ADVERTISE

  • Advertise with DZone

CONTRIBUTE ON DZONE

  • Article Submission Guidelines
  • Become a Contributor
  • Visit the Writers' Zone

LEGAL

  • Terms of Service
  • Privacy Policy

CONTACT US

  • 600 Park Offices Drive
  • Suite 300
  • Durham, NC 27709
  • support@dzone.com

Let's be friends: