Add a test for a useless @Contract by msridhar · Pull Request #1346 · uber/NullAway (original) (raw)

Walkthrough

A new static method uselessContract(@nullable Object o) was added to the NullnessChecker test class, accompanied by a corresponding test case. This method is annotated with a contract and returns a nullable object. The test case exercises the contract behavior and verifies that diagnostics are still produced when using this contract configuration.

Pre-merge checks and finishing touches

❌ Failed checks (1 warning)

✅ Passed checks (2 passed)

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Reviewing files that changed from the base of the PR and between 39d65f8 and 4fc1af9.

📒 Files selected for processing (1)

• nullaway/src/test/java/com/uber/nullaway/ContractsTests.java (2 hunks) 🧰 Additional context used 🧠 Learnings (1) 📚 Learning: 2025-08-14T18:50:06.159Z

Learnt from: msridhar
Repo: uber/NullAway PR: 1245
File: guava-recent-unit-tests/src/test/java/com/uber/nullaway/guava/NullAwayGuavaParametricNullnessTests.java:101-102
Timestamp: 2025-08-14T18:50:06.159Z
Learning: In NullAway JSpecify tests, when JDK version requirements exist due to bytecode annotation reading capabilities, prefer failing tests over skipping them on unsupported versions to ensure CI catches regressions and enforces proper JDK version usage for developers.

Applied to files:

• nullaway/src/test/java/com/uber/nullaway/ContractsTests.java 🔇 Additional comments (2)

nullaway/src/test/java/com/uber/nullaway/ContractsTests.java (2)

176-178: uselessContract contract and signature correctly model a “no-op” contract for NullAway.

The @Contract("null -> null") on uselessContract matches the implementation (return o;) and keeps the method return type @Nullable, so it doesn’t accidentally imply non-null on non-null inputs. This cleanly encodes the “useless” contract scenario the PR is targeting.

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195-199: New test4 precisely asserts that @Contract("null -> null") doesn’t suppress the nullable-return diagnostic.

Using a non-null Object o4 argument while expecting // BUG: Diagnostic contains: returning @Nullable expression is the right way to guard against misinterpreting the contract as strengthening the return type; this directly tests the PR objective.

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