asmhatre
fd3434c42d
Verifies five claims against primary sources rather than release-note prose: the org.testcontainers:junit-jupiter -> testcontainers-junit-jupiter rename (and the other 60 like it, per OpenRewrite's own Testcontainers2Migration recipe), that GenericContainer no longer implements org.junit.rules.TestRule anywhere in the 2.0.5 jar (confirmed exhaustively, not just for this one class), the real compiler/dependency-resolution breaks from bumping only a version number on existing JUnit 4 @ClassRule code, the literal 1.32 -> 1.44 default Docker API version bump in DockerClientProviderStrategy's bytecode (tied to the real Docker Engine 29 compatibility issue), and Spring Boot 4.1.1's BOM pinning 2.0.5. Built and tested with no Docker daemon available; one test class demonstrates a clean @EnabledIfDockerAvailable skip, guarded at the class level after the method-level guard was caught failing first.
testcontainers2
Companion module for Migrating to Testcontainers 2.0: Artifact Renames, Package Moves and JUnit 6 on ankurm.com.
What this is
Testcontainers 2.0 shipped on 2025-10-14 as a deliberately disruptive release: 61 artifacts
renamed, JUnit 4 support dropped from the type hierarchy itself (not deprecated — removed), and
a default Docker API version bump that quietly fixes a real compatibility break with current
Docker Engine releases. This module verifies each of those claims against a real jar, a real
Maven Central artifact history, or a real compiler run — never against a changelog's prose alone
— and runs the result against real JUnit 6.1.3. No docs/NN-topic.md chapters; everything beyond
what fits in the post itself is in the Javadoc on the two committed test classes and in the
captured transcripts below.
This module was built and tested in a sandbox with no Docker daemon available. Both test classes run (or cleanly skip) without one; nothing here asserts on a real container's output.
Self-correction made before this module was finished: the first draft of
NewPostgresContainerSkipsCleanlyTest put @EnabledIfDockerAvailable on the test method. That
compiles, and it is wrong — see the Javadoc on that class and
docs/output/01-guard-on-method-still-fails.txt for the real failure it produced before the fix.
Versions
| Dependency | Version | Verified against |
|---|---|---|
| Testcontainers | 2.0.5 | testcontainers-bom-2.0.5.pom; same version data-jpa-testcontainers verified Spring Boot 4.1.1's own BOM pins |
| JUnit Jupiter | 6.1.3 | maven-metadata.xml, <release> |
| AssertJ | 3.27.7 | maven-metadata.xml, <release> |
| JUnit 4 (test-scope only, for the reflective check) | 4.13.2 | pinned deliberately — see GenericContainerNoLongerImplementsTestRuleTest |
| JDK | 25 (Temurin) | java -version, this module's own build |
Quickstart
mvn test # 3 tests run; 1 skips cleanly, 0 failures
Test classes
| Class | What it proves | Needs Docker | Outcome here |
|---|---|---|---|
GenericContainerNoLongerImplementsTestRuleTest |
GenericContainer implemented org.junit.rules.TestRule by inheritance in 1.21.4; zero classes anywhere in the 2.0.5 core jar implement it |
No | Pass |
NewPostgresContainerSkipsCleanlyTest |
The relocated, non-generic org.testcontainers.postgresql.PostgreSQLContainer compiles and runs under JUnit 6, guarded correctly (class-level) by @EnabledIfDockerAvailable |
Yes (guarded) | Skipped |
Captured output
| File | Contents |
|---|---|
docs/output/00-full-test-run.txt |
mvn clean test — 3 tests, 1 clean skip, build green, with the guard on the class |
docs/output/01-guard-on-method-still-fails.txt |
The same class with @EnabledIfDockerAvailable on the method instead — a real IllegalStateException from GenericContainer.start(), because TestcontainersExtension.beforeAll starts every @Container field before any method-level condition runs |
docs/output/02-genericcontainer-testrule-removed-javap.txt |
javap proof of the TestRule removal: present via inheritance in 1.21.4, absent — exhaustively, jar-wide — in 2.0.5 |
docs/output/03-docker-api-version-bump-javap.txt |
javap proof that the hardcoded default Docker API version moved from 1.32 to 1.44 between 1.21.4 and 2.0.5, tied to the real GitHub issue where Docker Engine 29 rejects API 1.32 outright |
docs/output/04-legacy-pom-compiles-under-1.21.4.txt |
A classic @ClassRule public static PostgreSQLContainer<?> JUnit 4 test, compiling clean against 1.21.4 with no extra dependency |
docs/output/05-legacy-pom-fails-to-resolve-under-2.0.5.txt |
The identical source file; only the version property changed to 2.0.5. The build fails before it even reaches the TestRule question, because org.testcontainers:postgresql has no 2.0.5 release at all |
docs/output/06-maven-central-artifact-history.txt |
The real maven-metadata.xml for both org.testcontainers:junit-jupiter (frozen at 1.21.4) and org.testcontainers:testcontainers-junit-jupiter (starts at 2.0.0) — the permanent fork point behind the rename |
What's sourced from documentation, not run here
The full 61-artifact rename list and the composite Testcontainers2Migration OpenRewrite recipe
are quoted from OpenRewrite's own published recipe catalog, not executed in this sandbox — see
the post for the exact quotes and the link. Everything else above was compiled, run, or pulled
directly from a real jar or a real Maven Central response in this sitting.