Introduction to Testcontainers

Introduction to
Testcontainers

Oleg Šelajev
Developer relations
@shelajev
github.com/shelajev
oleg@atomicjar.com
Cora Iberkleid
Developer relations
@ciberkleid
github.com/ciberkleid
ciberkleid@vmware.com

Unit tests
Integration
tests
e2e

Common approaches to integration testing
In Integration tests we are interested in verifying the behavior and interactions of
multiple components.
For this purpose we can use:
● Shared instances
● Local installation
● In memory solutions
○ Mock server (Wiremock, Loki…)
○ In-memory service (h2, hsql...)
● Docker Compose

• Container lifecycle &
cleanup
• Container & service
conﬁguration
• Integration with
frameworks or tests

Testcontainers-java
• Created 7 years ago (Docker is 8 years old)
• github.com/testcontainers/testcontainers-java
• Uses docker-java API
• Integrates with frameworks, like Spring, JUnit
• Works with anything that runs in a Docker container

https:/
/www.thoughtworks.com/en-us/radar/languages-and-frameworks/testcontainers
We think it's a useful default
option for creating
a reliable environment for
running tests.
…
Our teams have consistently
found this library of
programmable, lightweight
and disposable containers to
make functional tests more
reliable.

Demo 0: Lifecycle!
● JUnit 5 integration
● Container lifecycle
● Shared containers (between test methods)

@Testcontainers
@Slf4j
public class LifeCycleTest {
@Container
GenericContainer container = new
GenericContainer(DockerImageName.parse("myRepo/myImg"));
public LifeCycleTest() {
log.info("In Constructor. Class instance: ", this);
}
@BeforeAll
public static void beforeAllMethod() {
log.info("In @BeforeAll. Static method.");
}
@BeforeEach
public void beforeEachMethod() {
log.info("In @BeforeEach. Class instance: " + this
+ ", Container id: ", container.getContainerId());
}
@Test
public void test1() {
log.info("In @Test 1. Class instance: ", this);
}
@Test
}
@AfterEach
public void afterEachMethod() {
log.info("In @AfterEach. Class instance: ", this);
}
@AfterAll
public static void afterAllMethod() {
log.info("In @AfterAll. Static method.");
}
}

@Testcontainers
@Slf4j
@Container
}
@BeforeAll
}
@BeforeEach
}
@Test
}
@Test
}
@AfterEach
}
@AfterAll
}
}
In @BeforeAll. Static method.
In Constructor. Class instance: LifeCycleTest@17d88132
Found Docker environment with local Unix socket (unix:///var/run/docker.sock)
Connected to docker
Pulling docker image: testcontainers/ryuk
Ryuk started - will monitor and terminate Testcontainers containers on JVM
exit
Checking the system...
✔ Docker server version should be at least 1.6.0
✔ Docker environment should have more than 2GB free disk space
Pulling docker image: myRepo/myImg
Container myRepo/myImg is starting:
b1c63a2738a6131ac06dd90bc334e621099b8a9d0092cfbc8899954495bd57c5
In @BeforeEach. Class instance: LifeCycleTest@17d88132, Container id:
@BeforeEach, Test1:
Connect to docker
Start ryuk
Check system
Start container
Execute BeforeEach method
Test 1

@Testcontainers
@Slf4j
@Container
}
@BeforeAll
}
@BeforeEach
}
@Test
}
@Test
}
@AfterEach
}
@AfterAll
}
}
Connected to docker
exit
In @Test 1. Class instance: LifeCycleTest@17d88132
In @AfterEach. Class instance: LifeCycleTest@17d88132
Ryuk removed container and associated volume(s): myRepo/myImg
After Test 1 “AfterEach”,
Ryuk cleans up container
Test 1

@Testcontainers
@Slf4j
@Container
}
@BeforeAll
}
@BeforeEach
}
@Test
}
@Test
}
@AfterEach
}
@AfterAll
}
}
Connected to docker
exit
In @Test 1. Class instance: LifeCycleTest@17d88132
In @AfterEach. Class instance: LifeCycleTest@17d88132
In Constructor. Class instance: LifeCycleTest@42d236fb
20e4227f6d5366c7f6ccb2ebf09eb5666bb75d20a4c307c6026870dc0fc0d3a1
In @BeforeEach. Class instance: LifeCycleTest@42d236fb, Container id:
20e4227f6d5366c7f6ccb2ebf09eb5666bb75d20a4c307c6026870dc0fc0d3a1
@BeforeEach, Test2:
Start new container
Execute BeforeEach method
Test 2
Test 1

@Testcontainers
@Slf4j
@Container
static GenericContainer container = new
}
@BeforeAll
}
@BeforeEach
}
@Test
}
@Test
}
@AfterEach
}
@AfterAll
}
}

@Testcontainers
@Slf4j
@Container
static GenericContainer container = new
}
@BeforeAll
}
@BeforeEach
}
@Test
}
@Test
}
@AfterEach
}
@AfterAll
}
}
Connected to docker
exit
8d8ff20a9f25dd8b0d4cd025406bdebfa9dcf5ab637ef53b5a815d97bc739b5a
In Constructor. Class instance: LifeCycleTest@63a5d002
In @BeforeEach. Class instance: LifeCycleTest@63a5d002, Container id:
In @Test 1. Class instance: LifeCycleTest@63a5d002
In @AfterEach. Class instance: LifeCycleTest@63a5d002
In Constructor. Class instance: LifeCycleTest@60e949e1
In @BeforeEach. Class instance: LifeCycleTest@60e949e1, Container id:
In @Test 2. Class instance: LifeCycleTest@60e949e1
In @AfterEach. Class instance: LifeCycleTest@60e949e1
In @AfterAll. Static method.
Container is reused
across tests
Test 2
Test 1

Demo 1: basics :)
● Docker container configuration
○ ports
○ logs
○ environment variables
○ startup commands
● Dockerfile support
https://github.com/shelajev/spring-one-tour-2022

Demo 2: common use cases
● Testcontainers modules
● Spring dynamic configuration
● Manual lifecycle control
● Containerized service initialization
● Database initialization strategies
● Chaos testing
https://github.com/shelajev/spring-one-tour-2022

TC - cloud
testcontainers.cloud

bit.ly/tcc-springone-tour22
testcontainers.cloud

What’s next?
— github.com/testcontainers/testcontainers-java
— testcontainers.org
— slack.testcontainers.org

Introduction to Testcontainers

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