BREAKING feat: use mutation framework for single-byte[] fuzz tests

[oetr]

Fuzz tests with a single byte[] parameter now also use the mutation framework by default.
This allows Jazzer annotations to be used in this setting as well.
To use classsic mode, set environment variable JAZZER_MUTATOR_FRAMEWORK to 0.
See discussion in #1022 for more background.

[Copilot]

Pull request overview

This pull request enables the mutation framework by default for fuzz tests with a single byte[] parameter, resolving issue #1022 where mutation framework annotations like @WithLength were being ignored for such tests. Previously, single byte[] parameter fuzz tests were automatically treated as "classic" mode tests, but now they use the mutation framework unless JAZZER_MUTATOR_FRAMEWORK=false is explicitly set.

Changes:

• Modified FuzzTargetRunner to remove the check that forced single byte[] parameters into classic mode
• Added @NotNull annotations to byte[] parameters in fuzz tests that use the mutation framework
• Updated build configurations to test fuzzers in both classic and mutation framework modes
• Added null checks in tests that run in both modes (LongStringFuzzer, KotlinStringCompareFuzzer)

Reviewed changes

Copilot reviewed 22 out of 22 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/main/java/com/code_intelligence/jazzer/driver/FuzzTargetRunner.java	Removed check that forced byte[] parameters into classic mode
src/main/java/com/code_intelligence/jazzer/mutation/mutator/lang/PrimitiveArrayMutatorFactory.java	Added special default max length for byte arrays (4096 vs 1000) to match libFuzzer defaults
tests/src/test/java/com/example/StringCompareFuzzer.java	Added @NotNull annotation to byte[] parameter
tests/src/test/java/com/example/OfflineInstrumentedFuzzer.java	Added @NotNull annotation to byte[] parameter
tests/src/test/java/com/example/ObjectEqualsStringFuzzer.java	Added @NotNull annotation to byte[] parameter
tests/src/test/java/com/example/LongStringFuzzer.java	Added null check for mutation framework compatibility
tests/src/test/java/com/example/KotlinStringCompareFuzzer.kt	Changed parameter to nullable ByteArray? and added null check
tests/BUILD.bazel	Duplicated tests to run in both classic and mutation framework modes, updated crash hashes
src/test/java/com/code_intelligence/jazzer/junit/BUILD.bazel	Added JAZZER_MUTATOR_FRAMEWORK=false to tests that should remain in classic mode
src/test/java/com/code_intelligence/jazzer/driver/BUILD.bazel	Added JAZZER_MUTATOR_FRAMEWORK=false to FuzzTargetRunnerTest
sanitizers/src/test/java/com/example/BUILD.bazel	Duplicated ObjectInputStreamDeserialization test for both modes
examples/src/main/java/com/example/*.java	Added @NotNull annotations to byte[] parameters in example fuzzers
examples/junit/src/test/java/com/example/*.java	Added @NotNull annotations to byte[] parameters in JUnit example tests
examples/BUILD.bazel	Duplicated example tests to run in both classic and mutation framework modes
examples/junit/src/test/java/com/example/BUILD.bazel	Duplicated JUnit example tests for both modes, updated crash hashes for CommandLineFuzzTest

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.