Back org.testng.Assert with AssertJ for behaviour-identical assertions#20
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Port the AssertJ-backed assertion implementation from testng-team/testng#3278 into this standalone artifact, so it can be dropped from the parent PR. - Assert: delegate assertNull/assertNotNull/assertSame/assertNotSame and assertThrows to AssertJ (behaviour-identical, only the failure message differs); remove the now-unused failSame/failNotSame helpers. Equality comparison intentionally keeps TestNG semantics (documented NOTE). - Mark org.testng.Assert @deprecated (recommend AssertJ); add @SuppressWarnings("deprecation") on Assertion. - pom: move assertj-core to compile scope (the main code depends on it). - docs: add MIGRATING_ASSERTIONS.md and link it from the README. expectThrows is kept unchanged (it returns the caught exception, which AssertJ's fluent API does not expose). Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Follow-up to the AssertJ delegation: extend it to the remaining behaviour-identical entry points. - assertTrue/assertFalse -> assertThat(condition).as(message).isTrue()/isFalse() - fail(message) and fail(message, cause) -> org.assertj.core.api.Assertions.fail(...) These flow through the OO Assertion/SoftAssert wrappers automatically (they delegate to org.testng.Assert), so soft assertions now use AssertJ for these checks too. Only the failure-message text changes; the pass/fail behaviour is unchanged. Updated the message-format-sensitive tests accordingly: - assertTrue/assertFalse message regexps now match AssertJ's output. - SoftAssertTest#testAssertAllCount no longer counts report lines (AssertJ messages are multi-line); it asserts the failed message is reported once. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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Jun 29, 2026
| * @deprecated TestNG no longer maintains its own assertion library. Use a dedicated assertion | ||
| * library such as <a href="https://assertj.github.io/doc/">AssertJ</a> instead. The OpenRewrite | ||
| * recipe {@code org.openrewrite.java.testing.testng.TestNgToAssertj} migrates the whole class | ||
| * automatically; see {@code docs/MIGRATING_ASSERTIONS.md} for details. |
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Will docs/MIGRATING_ASSERTIONS.md be part of the codebase? We should probably instead replace it with the web url of the repository so that people can come here and view this file to learn about the migration plan
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yes, the URL will be better
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Can we fix this, so that we can get this merged?
krmahadevan
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Jun 29, 2026
krmahadevan
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Jun 29, 2026
krmahadevan
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@juherr - Please check some of the observations that i have logged. I am not sure if they are discrepancies or not. Just wanted to still call them out.
Address review feedback (Krishnan): point the @deprecated javadoc to the hosted migration guide URL instead of the in-repo file path, so it is clickable from generated javadoc. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
krmahadevan
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Summary
Ports the AssertJ-backed assertion implementation from
testng-team/testng#3278 into this standalone
org.testng:testng-assertsartifact. Once released, the parent PR can drop thesetestng-asserts/src/mainchanges and simply depend on this artifact.Only assertions whose semantics are identical to AssertJ are delegated.
assertEquals/assertNotEqualsand the collection/map/array variants keep TestNG's own comparison semantics onpurpose — see the
NOTEcomment added toAssert#areEqualImpl. The only user-visible change is theAssertJ-formatted failure messages on the delegated assertions.
Two commits:
1. Delegate behaviour-identical assertions to AssertJ
assertNull/assertNotNull/assertSame/assertNotSameandassertThrows→ AssertJ.failSame/failNotSame.org.testng.Assert@Deprecated(javadoc recommends AssertJ; notforRemoval— thisartifact is the home of
Assert);@SuppressWarnings("deprecation")onAssertion.pom.xml:assertj-coremoved fromtestto compile scope.docs/MIGRATING_ASSERTIONS.md, linked from the README.2. Delegate assertTrue / assertFalse / fail to AssertJ
assertTrue/assertFalse→assertThat(condition).as(message).isTrue()/.isFalse().fail(message)/fail(message, cause)→org.assertj.core.api.Assertions.fail(...).Assertion/SoftAssertwrappers automatically (they delegate toorg.testng.Assert), so soft assertions use AssertJ for these checks too — no change needed inSoftAssert/Assertion.assertTrue/assertFalse/test2_failsmessage regexps now match AssertJ output, andSoftAssertTest#testAssertAllCountno longer counts report lines (AssertJ messages aremulti-line) — it asserts the failed message is reported exactly once.
Notes
expectThrowsis unchanged: it returns the caught exception, which AssertJ's fluent API doesnot expose.
failis the shared failure sink for the (deliberately non-delegated)assertEquals/ collectionassertions. Delegating it routes those through AssertJ's
AssertionFailedError(a subclass ofAssertionError); the message text is still TestNG's (built byformat(...)), only theexception subtype changes. The full suite confirms no
assertEquals/collection test regressed.Lists/Maps→ JDK refactor from the source PR is not included here (already done in thisrepo via
c4d2bd2).Testing
./mvnw clean test→ BUILD SUCCESS,Tests run: 181, Failures: 0, Errors: 0, Skipped: 1../mvnw dependency:treeconfirmsorg.assertj:assertj-core:3.27.7:compile(testng/guava staytest).🤖 Generated with Claude Code