[POC] Migrate `JUnit` asserts to `AssertJ` - impl #2307

Pankraz76 · 2025-05-09T15:01:03Z

[POC] Migrate JUnit asserts to AssertJ - impl

tryout:

mvn -U org.openrewrite.maven:rewrite-maven-plugin:run -Drewrite.recipeArtifactCoordinates=org.openrewrite.recipe:rewrite-testing-frameworks:RELEASE -Drewrite.activeRecipes=org.openrewrite.java.testing.assertj.JUnitToAssertj -Drewrite.exportDatatables=true

Pankraz76 · 2025-05-09T15:45:34Z

bug:

[junittoassertj] ReflectionValueExtractorTest.mappedIndexed:227 openrewrite/rewrite-testing-frameworks#728

[ERROR]   ReflectionValueExtractorTest.mappedIndexed:227 
expected: "a-value"
 but was: null

Pankraz76 · 2025-05-09T15:50:42Z

build success

Pankraz76 · 2025-05-09T16:12:21Z

bug:

missing dependency check: assertj-core openrewrite/rewrite-testing-frameworks#727

missing dependency check: assertj-core

      <dependency>
          <groupId>org.assertj</groupId>
          <artifactId>assertj-core</artifactId>
          <scope>test</scope>
      </dependency>

------------------
[ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.14.0:testCompile (default-testCompile) on project maven-api-plugin: Compilation failure: Compilation failure: 
[ERROR] /Users/vincent.potucek/IdeaProjects/maven/api/maven-api-plugin/src/test/java/org/apache/maven/api/plugin/descriptor/another/ExtendedPluginDescriptorTest.java:[24,35] package org.assertj.core.api does not exist
[ERROR] /Users/vincent.potucek/IdeaProjects/maven/api/maven-api-plugin/src/test/java/org/apache/maven/api/plugin/descriptor/another/ExtendedPluginDescriptorTest.java:[24,1] static import only from classes and interfaces
[ERROR] /Users/vincent.potucek/IdeaProjects/maven/api/maven-api-plugin/src/test/java/org/apache/maven/api/plugin/descriptor/another/ExtendedPluginDescriptorTest.java:[74,9] cannot find symbol
[ERROR]   symbol:   method assertThat(java.lang.String)
[ERROR]   location: class org.apache.maven.api.plugin.descriptor.another.ExtendedPluginDescriptorTest
[ERROR] /Users/vincent.potucek/IdeaProjects/maven/api/maven-api-plugin/src/test/java/org/apache/maven/api/plugin/descriptor/another/ExtendedPluginDescriptorTest.java:[75,9] cannot find symbol
[ERROR]   symbol:   method assertThat(java.lang.String)
[ERROR]   location: class org.apache.maven.api.plugin.descriptor.another.ExtendedPluginDescriptorTest
[ERROR] -> [Help 1]

Pankraz76 · 2025-05-10T14:33:46Z

kindly request some feedback

gnodet

The PR contains unrelated commis.

Pankraz76 · 2025-05-11T08:52:12Z

The PR contains unrelated commis.

yes will squash.

This anyway just demo.

I would suggest to go with one single source of truth and not pay double the cost of carry and raising questions.

Where was the question about migrating to AssertJ risen and discussed already? Please provide me a link, I might have overseen it in my mails.

Migrate JUnit asserts to AssertJ - migration #2309 (comment)

Need to pitch and sync with community. Might be obvious that we benefit from strict diet, but of course all need to be heard, as SSOT is just an illusion and individual.

@Bukama @olamy

Pankraz76 · 2025-05-11T08:57:07Z

Illustration of New Code Already Being Out of Sync (Considered Outdated)

GitHub reference: apache/maven#2236 (comment)

JUnit vs AssertJ Comparison

Medium article reference

In summary:

JUnit: Testing framework for defining, executing, and reporting tests
AssertJ: Library that enhances assertion readability and expressiveness

Personal Experience

In my last project using JUnit5, we still maintained a modern assertThat structure.

StackOverflow reference about the assertThat method.

Proposal: Standardizing Test Style

Key points:

Adopt a single test style using the generic assertThat pattern
Both JUnit and AssertJ share this API design pattern
The actual framework implementation becomes an abstraction layer detail

Current problems:

Mixing assertTrue and assertThat creates inconsistency
No common base increases setup time
Requires recognizing different patterns for the same purpose

Goal:

Reduce complexity from 3 patterns to 1
Framework choice becomes a separate discussion

gnodet · 2025-05-11T09:24:54Z

impl/maven-impl/src/test/java/org/apache/maven/impl/DefaultModelVersionParserTest.java

-        assertNotNull(v);
-        assertEquals("", v.toString());
+        assertThat(v).isNotNull();
+        assertThat(v.toString()).isEqualTo("");


Is there any isEmpty() assertion ?

Is there any isEmpty() assertion ?

If not, you can create custom assertions for AssertJ very easly. I do this quite a lot at work for custom objects/classes

might be a bug, as failed to choose: https://docs.openrewrite.org/recipes/java/testing/assertj/simplifyassertjassertion

@timtebeek

Or simply need to chain.

Any change not standardized is weakened.

Simplest way would be JUnit Jupiter best practices and allow both.

[POC] JUnit Jupiter best practices #2320

or (continuous) migrate JUnit asserts to AssertJ like seen here.

Both will cure generic assertTrue statements elevate into assertThat.
Which lib is actually an random impl. detail.

gnodet · 2025-05-11T09:26:36Z

impl/maven-impl/src/test/java/org/apache/maven/impl/AbstractVersionTest.java

-            assertNotEquals(v2, v1, "expected " + v2 + " != " + v1);
+            assertThat(Integer.signum(v1.compareTo(v2))).as("expected " + v1 + " > " + v2).isEqualTo(1);
+            assertThat(Integer.signum(v2.compareTo(v1))).as("expected " + v2 + " < " + v1).isEqualTo(-1);
+            assertThat(v2).as("expected " + v1 + " != " + v2).isNotEqualTo(v1);


Aren't those messages automatically generated by assertJ in case of failures ?

gnodet

I think there's still room for improvements.
It would be nice if the details of the commit include a command used to refactor.

Pankraz76 · 2025-05-11T09:31:34Z

It would be nice if the details of the commit include a command used to refactor.

you mean this?

https://docs.openrewrite.org/recipes/java/testing/assertj/junittoassertj#usage

mvn -U org.openrewrite.maven:rewrite-maven-plugin:run -Drewrite.recipeArtifactCoordinates=org.openrewrite.recipe:rewrite-testing-frameworks:RELEASE -Drewrite.activeRecipes=org.openrewrite.java.testing.assertj.JUnitToAssertj -Drewrite.exportDatatables=true

Pankraz76 · 2025-05-11T10:29:13Z

I think there's still room for improvements.

I would argue against this change now, realising and remembering that JUnit 5 looks almost 1o1 the same like AssertJ.

Both following and featuring assertThat prefix.

We could apply the API changes avoiding generic fluff assertTrue but use JUnit as its mandatory, which AssertJ might be not anymore.

Pankraz76 · 2025-05-11T10:37:39Z

JUnit 5 is equal, therefore superior to AssertJ.

only need to apply: JUnit Jupiter best practices

[POC] JUnit Jupiter best practices #2320

Pankraz76 changed the title ~~Migrate JUnit asserts to AssertJ~~ Migrate JUnit asserts to AssertJ May 9, 2025

Pankraz76 mentioned this pull request May 9, 2025

Pull #2291: Modernize codebase with Java improvements - Unnecessary throws #2291

Draft

Pankraz76 mentioned this pull request May 9, 2025

[junittoassertj] ReflectionValueExtractorTest.mappedIndexed:227 openrewrite/rewrite-testing-frameworks#728

Open

Pankraz76 marked this pull request as ready for review May 9, 2025 15:50

Pankraz76 changed the title ~~Migrate JUnit asserts to AssertJ~~ Migrate JUnit asserts to AssertJ - POC May 9, 2025

Pankraz76 mentioned this pull request May 9, 2025

Migrate JUnit asserts to AssertJ - migration #2309

Closed

Pankraz76 changed the title ~~Migrate JUnit asserts to AssertJ - POC~~ Migrate JUnit asserts to AssertJ - POC: impl/ May 9, 2025

This was referenced May 9, 2025

missing dependency check: assertj-core openrewrite/rewrite-testing-frameworks#727

Open

Migrate JUnit asserts to AssertJ checkstyle/checkstyle#17047

Closed

Issue #17047: Migrate JUnit asserts to AssertJ checkstyle/checkstyle#17048

Closed

Pankraz76 marked this pull request as draft May 10, 2025 14:32

gnodet requested changes May 11, 2025

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Pankraz76 mentioned this pull request May 11, 2025

[MNG-8686] Add SourceRoot.matcher(boolean) method #2236

Open

Pankraz76 changed the title ~~Migrate JUnit asserts to AssertJ - POC: impl/~~ [POC] Migrate JUnit asserts to AssertJ - impl May 11, 2025

[POC] Migrate JUnit asserts to AssertJ - impl

432c7a3

Pankraz76 force-pushed the fix-write-fix-JUnitToAssertj branch from e3d5e17 to 432c7a3 Compare May 11, 2025 09:18

Pankraz76 requested a review from gnodet May 11, 2025 09:20

gnodet reviewed May 11, 2025

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[POC] Migrate `JUnit` asserts to `AssertJ` - impl #2307

[POC] Migrate `JUnit` asserts to `AssertJ` - impl #2307

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[POC] Migrate JUnit asserts to AssertJ - impl #2307

Are you sure you want to change the base?

[POC] Migrate JUnit asserts to AssertJ - impl #2307

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Illustration of New Code Already Being Out of Sync (Considered Outdated)

JUnit vs AssertJ Comparison

Personal Experience

Proposal: Standardizing Test Style

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[POC] Migrate `JUnit` asserts to `AssertJ` - impl #2307

[POC] Migrate `JUnit` asserts to `AssertJ` - impl #2307

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