feats: extend ValuePool by new fields : files, and maxMutations #1033

oetr · 2026-01-21T12:37:45Z

The users can now supply glob patterns to the @ValuePool annotation by using the new field String[] files---files matching the patterns will be loaded as byte []. The field uses the glob: syntax of java.nio.file.PathMatcher.

Example:

@ValuePool(files={"src/test/resources/**", "/home/user/fuzzing-corpus/compression/zip/**"})

In addition, by setting the new field maxMutations, the users can now control up to how many times (by default 1) values selected from @ValuePool will be mutated by the underlying mutator in one mutation operation.

Copilot

Pull request overview

This PR extends the @ValuePool annotation to support two new capabilities: (1) loading files as byte arrays using glob patterns via a new files field, and (2) controlling mutation iterations via a new maxMutations field.

Changes:

Added files field to @ValuePool annotation for glob-based file loading
Added maxMutations field to control mutation iterations on pool values
Implemented file pattern matching and path resolution in ValuePoolRegistry
Updated mutation logic to apply multiple mutations based on maxMutations
Added caching for ArgumentsMutator instances and file reads
Comprehensive test coverage for file loading feature
Extensive documentation updates

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 16 comments.

Show a summary per file

File	Description
src/main/java/com/code_intelligence/jazzer/mutation/annotation/ValuePool.java	Added `files` and `maxMutations` fields to annotation with documentation
src/main/java/com/code_intelligence/jazzer/mutation/support/ValuePoolRegistry.java	Implemented glob pattern matching, file loading, and maxMutations extraction with path resolution logic
src/main/java/com/code_intelligence/jazzer/mutation/mutator/lang/ValuePoolMutatorFactory.java	Updated mutate/crossOver to apply multiple mutations based on maxMutations
src/test/java/com/code_intelligence/jazzer/mutation/support/ValuePoolsTest.java	Added comprehensive tests for file loading patterns and updated test helpers
src/main/java/com/code_intelligence/jazzer/mutation/ArgumentsMutator.java	Added caching for ArgumentsMutator instances to improve performance
src/main/java/com/code_intelligence/jazzer/junit/FuzzTestExecutor.java	Set system property for baseDir to enable ValuePoolRegistry file resolution
docs/mutation-framework.md	Added extensive documentation for ValuePool features including examples and usage patterns

Comments suppressed due to low confidence (1)

src/test/java/com/code_intelligence/jazzer/mutation/support/ValuePoolsTest.java:415

The test helper withValuePoolImplementation is missing the maxMutations() method implementation. Since maxMutations() is now part of the @valuepool annotation interface, this anonymous implementation must override it. Without this method, using this test helper will result in runtime errors when the annotation's maxMutations() method is called.

    return new ValuePool() {
      @Override
      public String[] value() {
        return value;
      }

      @Override
      public String[] files() {
        return files;
      }

      @Override
      public double p() {
        return p;
      }

      @Override
      public String constraint() {
        return constraint;
      }

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docs/mutation-framework.md

src/main/java/com/code_intelligence/jazzer/mutation/support/ValuePoolRegistry.java

src/main/java/com/code_intelligence/jazzer/mutation/annotation/ValuePool.java

src/main/java/com/code_intelligence/jazzer/mutation/support/ValuePoolRegistry.java

src/test/java/com/code_intelligence/jazzer/mutation/support/ValuePoolsTest.java

src/main/java/com/code_intelligence/jazzer/mutation/mutator/lang/ValuePoolMutatorFactory.java

docs/mutation-framework.md

src/main/java/com/code_intelligence/jazzer/mutation/support/ValuePoolRegistry.java

src/main/java/com/code_intelligence/jazzer/mutation/mutator/lang/ValuePoolMutatorFactory.java

Copilot

Pull request overview

Copilot reviewed 8 out of 8 changed files in this pull request and generated 9 comments.

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src/test/java/com/code_intelligence/jazzer/mutation/support/ValuePoolsTest.java

src/main/java/com/code_intelligence/jazzer/mutation/support/ValuePoolRegistry.java

docs/mutation-framework.md

src/test/java/com/code_intelligence/jazzer/mutation/support/ValuePoolsTest.java

src/main/java/com/code_intelligence/jazzer/mutation/mutator/lang/ValuePoolMutatorFactory.java

src/main/java/com/code_intelligence/jazzer/junit/FuzzTestExecutor.java

Marcono1234

Hopefully these comments are useful. Feel free to consider them only as suggestions or ignore them completely.

Please let me know if these comments are not useful or if you consider them disruptive.

docs/mutation-framework.md

src/main/java/com/code_intelligence/jazzer/mutation/annotation/ValuePool.java

src/main/java/com/code_intelligence/jazzer/mutation/support/ValuePoolRegistry.java

src/test/java/com/code_intelligence/jazzer/mutation/support/ValuePoolsTest.java

oetr · 2026-01-23T17:12:14Z

Hopefully these comments are useful. Feel free to consider them only as suggestions or ignore them completely.

Please let me know if these comments are not useful or if you consider them disruptive.

@Marcono1234 Your reviews are welcome, and helpful 😄 Thanks!

The number of fields in ValuePool is getting large, so that construction using positional args is becoming confusing. Using a builder simplifies the tests.

Don't generate the same mutator for the same fuzz test method multiple times. Before this change, a mutator was generated for each crash file in fuzzing mode.

simonresch

Looks good!

Very thorough test coverage. As with our C++ detour I keep getting surprised how complicated it is to do a simple file glob. 😄 But this might come in handy in the future.

simonresch · 2026-02-11T13:51:55Z

src/main/java/com/code_intelligence/jazzer/mutation/ArgumentsMutator.java

  private final Method method;
  private final InPlaceProductMutator productMutator;

+  private static final Map<Method, ArgumentsMutator> mutatorsCache = new ConcurrentHashMap<>();


We might be able to fix the JUnit integration to not create multiple mutators for the same method since it already has a store. I believe the problem is the ExecutionContext in https://github.com/CodeIntelligenceTesting/jazzer/blob/main/src/main/java/com/code_intelligence/jazzer/junit/FuzzTestExtensions.java#L198 which is the invocation context and not the test execution context. This seems to cause the serializer not to be cached correctly. Changing it to

private static SeedSerializer getOrCreateSeedSerializer(ExtensionContext extensionContext) { Method method = extensionContext.getRequiredTestMethod(); // Use the parent context (test method level) to share the store across all invocations // of the same test method. Each invocation gets its own ExtensionContext, so using // the current context would create a new SeedSerializer for each seed. ExtensionContext methodContext = extensionContext.getParent().orElse(extensionContext); ...

seems to fix multiple mutators being created for each crash file.

simonresch · 2026-02-11T14:48:07Z

src/main/java/com/code_intelligence/jazzer/mutation/support/GlobUtils.java

+    return SPECIAL_CHARS.indexOf(c) != -1;
+  }
+
+  protected static Path unescapeGlobChars(Path glob) {


This seems to be unused.

simonresch · 2026-02-11T14:52:09Z

src/main/java/com/code_intelligence/jazzer/mutation/annotation/ValuePool.java

+   *
+   * <p>Relative glob patterns are resolved against the working directory.
+   *
+   * <p>Patterns that start with <code>{</code> or <code>[</code>@code are treated as relative to


Possible typo: @code

simonresch · 2026-02-11T14:54:08Z

src/main/java/com/code_intelligence/jazzer/mutation/support/GlobUtils.java

+   * @param glob
+   * @return true if the glob contains unescaped "**"
+   */
+  protected static boolean isRecursive(String glob) {


Seems to be unused.

simonresch · 2026-02-11T15:11:12Z

src/test/java/com/code_intelligence/jazzer/mutation/support/TestSupport.java

+
+  private static final boolean ON_WINDOWS = FileSystems.getDefault().getSeparator().equals("\\");
+
+  public static void mockSourceDirectory(Path base) throws IOException {


WDYT about moving this into the GlobUtilsTest? Here it seems quite far away from where this specific directory structure is used.

simonresch · 2026-02-11T15:27:54Z

docs/mutation-framework.md

+    Map<String, Integer> map = new HashMap<>();
+    map.put("one", 1);
+    map.put("two", 2);
+    static Stream<?> edgeCases() {


Suggested change

Map<String, Integer> map = new HashMap<>();

map.put("one", 1);

map.put("two", 2);

static Stream<?> edgeCases() {

static Stream<?> edgeCases() {

Map<String, Integer> map = new HashMap<>();

map.put("one", 1);

map.put("two", 2);

Copilot AI review requested due to automatic review settings January 21, 2026 12:37

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oetr force-pushed the CIF-1907-add-glob-pattern-to-value-pool branch 4 times, most recently from ed09c59 to e2cc773 Compare January 21, 2026 19:08

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oetr force-pushed the CIF-1907-add-glob-pattern-to-value-pool branch 3 times, most recently from 6d874ba to 112ab04 Compare January 22, 2026 07:16

oetr marked this pull request as ready for review January 22, 2026 07:48

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oetr force-pushed the CIF-1907-add-glob-pattern-to-value-pool branch from 112ab04 to 49403fd Compare January 22, 2026 14:38

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oetr force-pushed the CIF-1907-add-glob-pattern-to-value-pool branch 2 times, most recently from 4818c8e to a16453d Compare February 2, 2026 09:30

oetr marked this pull request as draft February 2, 2026 11:17

oetr force-pushed the CIF-1907-add-glob-pattern-to-value-pool branch 2 times, most recently from 23d9b67 to d7004da Compare February 4, 2026 08:37

oetr marked this pull request as ready for review February 4, 2026 09:22

oetr added 5 commits February 10, 2026 15:01

chore: build ValuePool using a builder in tests

6beff90

The number of fields in ValuePool is getting large, so that construction using positional args is becoming confusing. Using a builder simplifies the tests.

feat: cache mutators and value pools for each method

f81f15c

Don't generate the same mutator for the same fuzz test method multiple times. Before this change, a mutator was generated for each crash file in fuzzing mode.

feat: ValuePool can load files that match directory patterns

10e638e

feat: add configurable max number of mutations for ValuePools

c88cfcc

feat: document @valuepool

928c9a2

oetr force-pushed the CIF-1907-add-glob-pattern-to-value-pool branch from d7004da to 928c9a2 Compare February 10, 2026 14:01

simonresch approved these changes Feb 11, 2026

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simonresch reviewed Feb 11, 2026

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		private static final boolean ON_WINDOWS = FileSystems.getDefault().getSeparator().equals("\\");

		public static void mockSourceDirectory(Path base) throws IOException {

feats: extend ValuePool by new fields : files, and maxMutations #1033

Are you sure you want to change the base?

feats: extend ValuePool by new fields : files, and maxMutations #1033

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oetr commented Jan 23, 2026

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oetr commented Jan 21, 2026 •

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