Test case for #1528

[msridhar]

Fixes #1528

Add a test case to ensure we handle this case correctly.

Summary by CodeRabbit

• Tests
  • Added regression test to enhance validation of nullability inference with generic method type parameters and method references. The test specifically covers stream operations combined with wildcard type parameters, strengthening test coverage for complex type inference scenarios and improving overall quality assurance.

[coderabbitai]

Walkthrough

A regression test is added to GenericMethodLambdaOrMethodRefArgTests to exercise nullability inference with generic method type parameters and method references. The test case defines a generic and method accepting a Stream<T> and a Function<T, @nullable Pair>, then tests two scenarios involving method references over Map.entrySet().stream(). One method reference variant is expected to produce a nullability-related diagnostic, while another using wildcard type parameters is expected to compile without diagnostics.

Possibly related PRs

• PR #1428: Exercises lambda target-type and type-variable annotation propagation in similar generic method and method reference contexts
• PR #1471: Alters generic-method type-variable inference behavior in GenericsChecks.java, directly affecting how unconstrained type variables are treated in the same inference codepath
• PR #1473: Fixes nullability-inference for generic method types by restoring nullability annotations that javac elides at call sites

Suggested reviewers

• yuxincs
• lazaroclapp

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 33.33% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title 'Test case for #1528' is directly related to the pull request objective of adding a regression test for issue #1528.
Linked Issues check	✅ Passed	The pull request adds a regression test for issue #1528 covering the generic method type parameter nullability matching scenario described in the linked issue.
Out of Scope Changes check	✅ Passed	All changes are within scope: a single new test method (issue1528) in the appropriate test class addressing the exact scenario from the linked issue.

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✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch issue-1528

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[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Inline comments:
In
`@nullaway/src/test/java/com/uber/nullaway/jspecify/GenericMethodLambdaOrMethodRefArgTests.java`:
- Around line 996-999: The test currently asserts a diagnostic for
Pair::fromMapEntry inside the method Test and(Map<String, String> map), which
encodes the regression instead of the intended fix; remove the BUG comment on
the return line (the "// BUG: Diagnostic contains: parameter type of referenced
method is Entry<String, `@Nullable` String>") so that the call return
and(map.entrySet().stream(), Pair::fromMapEntry) is allowed/compiles again per
issue `#1528` and no diagnostic is expected for Pair::fromMapEntry.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: ASSERTIVE

Plan: Pro

Run ID: 8bf36a28-0afe-4bf9-a082-0459286fc333

📥 Commits

Reviewing files that changed from the base of the PR and between da3cc0d and a492536.

📒 Files selected for processing (1)

• nullaway/src/test/java/com/uber/nullaway/jspecify/GenericMethodLambdaOrMethodRefArgTests.java

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 88.52%. Comparing base (da3cc0d) to head (a492536).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff            @@
##             master    #1556   +/-   ##
=========================================
  Coverage     88.52%   88.52%           
  Complexity     2862     2862           
=========================================
  Files           103      103           
  Lines          9522     9522           
  Branches       1911     1911           
=========================================
  Hits           8429     8429           
  Misses          528      528           
  Partials        565      565           

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