SONARJAVA-6305 Do not raise S8220 in tests where DateTimeException is expected

[aurelien-coet-sonarsource]

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[hashicorp-vault-sonar-prod]

SONARJAVA-6305

[sonar-review-alpha]

Summary

S8220 false-positive suppression in tests expecting DateTimeException

This PR prevents the S8220 rule (InstantConversionsCheck - warns about unsafe Instant.from() conversions) from raising issues in test code that explicitly expects DateTimeException to be thrown.

What changed:

1. Refactored isTryCatchFail detection logic from AbstractOneExpectedExceptionRule → UnitTestUtils to enable reuse
2. Created ExpectedExceptionFilter that suppresses S8220 issues in test contexts where DateTimeException is expected
3. Integrated the new filter into the analysis pipeline

Patterns recognized:

• JUnit 4: @Test(expected = DateTimeException.class)
• TestNG: @Test(expectedExceptions = DateTimeException.class)
• JUnit 5: assertThrows(), assertThrowsExactly()
• AssertJ: assertThatThrownBy(), assertThatExceptionOfType(), catchThrowableOfType()
• Try-catch-fail: Try blocks ending with fail() inside catch blocks expecting DateTimeException
• Union types in catch clauses

What reviewers should know

Where to start:

• Review the test file src/test/files/filters/ExpectedExceptionFilter.java first (~151 lines) — it clearly demonstrates all supported scenarios with comments indicating expected behavior (// NoIssue vs // WithIssue)
• Then examine ExpectedExceptionFilter.java implementation to see how each pattern is detected

Key decisions:

• The filter treats exact type matches and supertype matches differently: assertThrowsExactly(RuntimeException.class) is treated as "broad" (suppresses issues) but isExactlyInstanceOf(RuntimeException.class) is not (raises issues). This distinction is intentional for precision.
• The filter only suppresses issues within the test's expected exception scope — code outside the assertion/try-block still reports issues (see junit5AssertThrowsOnlyFiltersExecutable test case)
• DateTimeException supertypes (RuntimeException, Exception, Throwable) are recognized to handle cases where tests catch the broader type

Non-functional changes to review:

• Minor formatting fixes in UnitTestUtils.java (indentation alignment, spacing before .equals())
• Test assertion counts updated from 6→7 filters in PostAnalysisIssueFilterTest

Watch for:

• Union type handling in catch clauses (multi-type catches with |)
• AssertJ method chaining — the filter follows chains to locate the executable/code block being tested
• Edge case: assignments in annotation arguments (e.g., @Test(expected = SomeClass.class))

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Quality Gate passed

Issues
0 New issues
0 Fixed issues
0 Accepted issues

Measures
0 Security Hotspots
0 Dependency risks
94.1% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube

[sonar-review-alpha]

LGTM! ✅

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