GH-3873: Deprecate JUnit 4 utilities in the project #3878

chickenchickenlove · 2025-04-29T23:27:51Z

Fixes Deprecate JUnit 4 utilities in the project #3873

The class that implements MethodRule in Junit4 is called whenever each test method is executed.
Before executing the test method, it configures the log level.
Then, after executing the test method, it returns the log level back.

Like MethodRule in Junit4, the interface InvocationInterceptor in Junit5 provides interceptTestMethod(...).
So, I migrated MethodRule to InvocationInterceptor.

Signed-off-by: chickenchickenlove <[email protected]>

sobychacko · 2025-04-30T15:44:55Z

...-kafka-test/src/main/java/org/springframework/kafka/test/extensions/Log4j2LevelAdjuster.java

 *
 */
-public class Log4j2LevelAdjuster implements MethodRule {
+public class Log4j2LevelAdjuster implements InvocationInterceptor {


Where is this class used with Junit5?

This is not correct.
The class is public and for end-user consumption.
It is totally wrong to change the class contract.
We develop here a library for target projects, so whatever is public cannot be changed like this.
We have to revert the change here and deprecate it.
We may come up with JUnit 5 variant. But that is a different story.
You may take a inspiration from Spring AMQP: https://github.com/spring-projects/spring-amqp/blob/main/spring-rabbit-junit/src/main/java/org/springframework/amqp/rabbit/junit/LogLevels.java

Maybe we can deprecate it on the 3.3.x line and then still remove it in 4.0.0. Thoughts?

Yeah... That would be inconsistent with Spring Framework plans.
They do deprecate JUnit 4 in version 7.0.

@sobychacko

As @artembilan mentioned before, this class is to configure log levels.
Also, It can be replace with @LogLevels in Junit5.

artembilan · 2025-04-30T15:53:46Z

...-kafka-test/src/main/java/org/springframework/kafka/test/extensions/Log4j2LevelAdjuster.java

 *
 */
-public class Log4j2LevelAdjuster implements MethodRule {
+public class Log4j2LevelAdjuster implements InvocationInterceptor {


This is not correct.
The class is public and for end-user consumption.
It is totally wrong to change the class contract.
We develop here a library for target projects, so whatever is public cannot be changed like this.
We have to revert the change here and deprecate it.
We may come up with JUnit 5 variant. But that is a different story.
You may take a inspiration from Spring AMQP: https://github.com/spring-projects/spring-amqp/blob/main/spring-rabbit-junit/src/main/java/org/springframework/amqp/rabbit/junit/LogLevels.java

artembilan · 2025-04-30T15:55:02Z

build.gradle

@@ -378,9 +377,6 @@ project ('spring-kafka-test') {
 		api 'org.junit.platform:junit-platform-launcher'
 		optionalApi "org.hamcrest:hamcrest-core:$hamcrestVersion"
 		optionalApi "org.mockito:mockito-core:$mockitoVersion"
-		optionalApi ("junit:junit:$junit4Version") {


This is not correct.
We are talking about deprecation of the utility, but not total removal.
Therefore dependency and deprecated classes must still be here.
Again: we develop library, so whatever we do here might break target projects using our library.

Removing it temporary locally is a good way to check if we still have any JUnit 4 tests left. 😄

artembilan · 2025-04-30T15:57:52Z

.../src/test/java/org/springframework/kafka/test/extensions/AddressableEmbeddedBrokerTests.java

@@ -14,7 +14,7 @@
 * limitations under the License.
 */

-package org.springframework.kafka.test.rule;
+package org.springframework.kafka.test.extensions;


Doesn't look like this class logic does something with log adjustment.
Might be better to move it to some other package.
Probably to the root one alongside with the EmbeddedKafkaKraftBrokerTests

…oject" This reverts commit 2da4d5d. Signed-off-by: chickenchickenlove <[email protected]>

Signed-off-by: chickenchickenlove <[email protected]>

chickenchickenlove · 2025-05-01T05:26:04Z

@artembilan

There are no test cases using Junit4 in spring-kafka project. So, I don't need to fix any test case.
I tried to replace Components to Deprecate with JUnit5 one.
- However, there were no usages of deprecated components in the current spring-kafka codebase.
- However, many parts of the test documentation were written using JUnit4, so I updated them.
Added @Deprecated to concreate class of JUnit4 interface.
Update Java docs to use Junit5 instead of Junit4.

I’m not sure if I’m on the right track with my work.
The work I just did was based on the following assumptions:

Migrate all JUnit4 test code used in spring-kafka to JUnit 5.
Identify the JUnit4-related deprecated components in Spring and migrate them to Spring JUnit5 equivalents (including both documentation and code).
For any JUnit 4-based public interfaces exposed to users, add @Deprecated warnings.

Is my understanding correct?
If I’ve misunderstood anything, I would appreciate it if you could correct me.
I’m sorry for bothering you.
This kind of work is new to me, so there are many parts that I find confusing.

Sorry again and Thanks for your time. 🙇‍♂️

artembilan · 2025-05-01T13:51:37Z

spring-kafka-docs/src/main/antora/modules/ROOT/pages/testing.adoc

@@ -121,15 +121,19 @@ The following example configuration creates topics called `cat` and `hat` with f

 [source, java]
 ----
+@ExtendWith(SpringExtension.class)


Why @SpringJUnitConfig doesn't work for us here?

artembilan · 2025-05-01T13:53:39Z

spring-kafka-docs/src/main/antora/modules/ROOT/pages/testing.adoc

@@ -350,6 +354,38 @@ They include:
 * xref:testing.adoc#kafka-testing-junit4-class-rule[JUnit4 Class Rule]
 * xref:testing.adoc#kafka-testing-embeddedkafka-annotation[`@EmbeddedKafka` Annotation or `EmbeddedKafkaBroker` Bean]

+[[kafka-testing-junit4-embedded-broker]]
+=== Junit4 Embedded Broker


I think if we deprecate JUnit 4, we just should mention that we have done that and recommend to migrate to JUnit 5 without any further advises how to configure JUnit 4.

I removed all contents about JUnit4 and left comment for asking migration to JUnit5.
Thanks a lot 🙇‍♂️

artembilan · 2025-05-01T13:54:20Z

spring-kafka-test/src/main/java/org/springframework/kafka/test/context/EmbeddedKafka.java

@@ -43,7 +43,7 @@
 * <p>
 * The typical usage of this annotation is like:
 * <pre class="code">
- * &#064;RunWith(SpringRunner.class)
+ * &#064;ExtendWith(SpringExtension.class)


DITTO about @SpringJUnitConfig.
It is very rare situation when we need to use @ExtendWith(SpringExtension.class).

artembilan · 2025-05-01T13:54:56Z

spring-kafka-test/src/main/java/org/springframework/kafka/test/rule/Log4j2LevelAdjuster.java

 */
+@Deprecated(since = "4.0")


Missed forRemoval = true.
We really are going to remove it in the next 4.1 or 4.2

artembilan · 2025-05-01T13:55:51Z

spring-kafka-test/src/main/java/org/springframework/kafka/test/rule/Log4j2LevelAdjuster.java

@@ -37,8 +37,11 @@
 * @author Dave Syer
 * @author Artem Bilan
 * @author Gary Russell
- *
+ * @author Sanghyeok An
+ * @deprecated since Spring for Apache Kafka 4.0 in favor of the


This is not good style since the @author section becomes not visible and we lose a credit for those who contributed to the class.

You use too many words for the @deprecated tag. It is really obvious if we use version without project mentioning. If that is not a case, we would mention the target library name.
So, for me this sentence could be like this:

@deprecated since 4.0 in favor of {@link org.springframework.kafka.test.condition.LogLevels}.

That is also obvious by LogLevels design that it is for JUnit 5.

@artembilan

This is not good style since the @author section becomes not visible and we lose a credit for those who contributed to the class.

Sorry to say that I don't understand your point. 😓
other spring projects do same things. for examples,

springframework/lang/NonNull.java

springframework/core/env/JOptCommandLinePropertySource

I built the java docs in my local and I can't see @author in all java docs.
However, spring-kafka java docs don't display @author tags at all as well.(https://javadoc.io/doc/org.springframework.kafka/spring-kafka/latest/org/springframework/kafka/listener/CommonErrorHandler.html)

Could you let me know about not visiable @author tag...? 😢
Thanks for your time... 🙇‍♂️

Sure! Different projects may have different styles or just don't care about readability.
I try to be with my code as friendly as possible.
That style:

makes it hard for me to read the code, so I imaging that not only me, therefore in my code I try to separate those sections for readers of my code.

If you use @ here in GH comments, please, wrap that into code snippet.
Otherwise GH treats it as mentioning of that user here on GH.
Just try to follow that @author link. Since there that GH user you have just called him into our discussion 🤷

I'm not sure what Javadoc link you show there, but the one we provide on our site has @author list: https://docs.spring.io/spring-kafka/docs/3.3.5/api/org/springframework/kafka/listener/AbstractMessageListenerContainer.html.

Either way, my point is not about Javadoc tool, but rather source code to be readable clearly.
In the end that's why it is an Open Source!

Thanks for your comments!!
I totally misunderstood your points. 😅
I thought you were letting me know that the author would not be visible in the JavaDoc.

artembilan · 2025-05-01T13:59:26Z

spring-kafka-docs/src/main/antora/modules/ROOT/pages/testing.adoc

+
+}
+----
+
 [[kafka-testing-junit4-class-rule]]
 === JUnit4 Class Rule


I would prefer to have all the JUnit 4 text removed in favor of a single sentence that its support is deprecated for removal in the next minor version.

Signed-off-by: chickenchickenlove <[email protected]>

artembilan · 2025-05-02T14:04:51Z

spring-kafka-docs/src/main/antora/modules/ROOT/pages/testing.adoc

@@ -56,8 +56,7 @@ If this is not possible for some reason, note that the `consumeFromEmbeddedTopic
 Since it does not have access to the consumer properties, you must use the overloaded method that takes a `seekToEnd` boolean parameter to seek to the end instead of the beginning.
 ====

-NOTE: The `EmbeddedKafkaRule` JUnit 4 rule has been removed in version 4.0.
-For JUnit 4, you should use the `EmbeddedKafkaKraftBroker` directly or migrate to JUnit 5 with the `@EmbeddedKafka` annotation.
+NOTE: `Spring Kafka` no longer supports JUnit4. Please consider migrating from JUnit4 to JUnit5.


Our rule is One sentence per line: https://asciidoctor.org/docs/asciidoc-recommended-practices/

And another nit-pick.
Since this is a technical documentation it has to be in a business language and impersonal.
Therefore words, like you, we, please have to be avoided.

I know we have a lot like this in our doc, but that doesn't mean that we have to pollute more.

artembilan · 2025-05-02T14:08:59Z

spring-kafka-docs/src/main/antora/modules/ROOT/pages/testing.adoc

@@ -121,15 +120,19 @@ The following example configuration creates topics called `cat` and `hat` with f

 [source, java]
 ----
+@SpringJUnitConfig
+@EmbeddedKafka(
+		partitions = 5,


It is not clear from this view, but can we be sure that we don't use tabs for indents?

I think I had used tabs for indents.
Now, I fixed it with 8 spaces fir indents.
I attached rendered image! Please refer it!

sbrannen · 2025-05-02T14:36:23Z

spring-kafka-docs/src/main/antora/modules/ROOT/pages/testing.adoc

@@ -56,8 +56,7 @@ If this is not possible for some reason, note that the `consumeFromEmbeddedTopic
 Since it does not have access to the consumer properties, you must use the overloaded method that takes a `seekToEnd` boolean parameter to seek to the end instead of the beginning.
 ====

-NOTE: The `EmbeddedKafkaRule` JUnit 4 rule has been removed in version 4.0.
-For JUnit 4, you should use the `EmbeddedKafkaKraftBroker` directly or migrate to JUnit 5 with the `@EmbeddedKafka` annotation.
+NOTE: `Spring Kafka` no longer supports JUnit4. Please consider migrating from JUnit4 to JUnit5.


I would not refer to JUnit Jupiter as "JUnit 5", especially since we (the JUnit team) will be releasing JUnit Jupiter 6 as part of "JUnit 6" later this year.

In other words, I think it is better to refer to JUnit Jupiter as "JUnit Jupiter" to avoid any confusion and unnecessary updates to documentation in the future.

I would also suggest that "JUnit Jupiter" be used consistently across the documentation.

Signed-off-by: chickenchickenlove <[email protected]>

artembilan · 2025-05-03T02:04:13Z

spring-kafka-docs/src/main/antora/modules/ROOT/pages/testing.adoc

+[NOTE]
+====
+`Spring Kafka` no longer supports `JUnit4`.
+Migration to `JUnit Jupiter` is recommended.


Those words don’t justify to be a code.
Plus, why stick 4 to JUnit word?

Also, the official project name is Spring for Apache Kafka and since we don’t use code wrapping here why do that for JUnit projects?

Signed-off-by: chickenchickenlove <[email protected]>

spring-projectsGH-3873: Deprecate JUnit 4 utilities in the project

2da4d5d

Signed-off-by: chickenchickenlove <[email protected]>

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chickenchickenlove added 2 commits May 1, 2025 12:37

Revert "spring-projectsGH-3873: Deprecate JUnit 4 utilities in the pr…

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…oject" This reverts commit 2da4d5d. Signed-off-by: chickenchickenlove <[email protected]>

Addressing PR review

c8839a5

Signed-off-by: chickenchickenlove <[email protected]>

chickenchickenlove force-pushed the GH-3873 branch from 0bc99b7 to c8839a5 Compare May 1, 2025 05:08

Fixes lint error.

6fe5470

Signed-off-by: chickenchickenlove <[email protected]>

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Addressing PR review

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GH-3873: Deprecate JUnit 4 utilities in the project #3878

GH-3873: Deprecate JUnit 4 utilities in the project #3878

chickenchickenlove commented Apr 29, 2025

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		*/
		@Deprecated(since = "4.0")

GH-3873: Deprecate JUnit 4 utilities in the project #3878

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GH-3873: Deprecate JUnit 4 utilities in the project #3878

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