JavaRIG

Description

Small, reflection-based random instance generator for Java. Given a type, JavaRIG builds a random instance by walking setters (and common JDK types), with guards to prevent infinite recursion.

Latest release: 1.1.1 (2023-10-28).

Supported types

Source of truth: io.javarig.TypeEnum and the corresponding TypeGenerator.

Category	Types
Primitives / wrappers	Integer, Long, Double, Float, Short, Byte, Boolean, Character
Text	String
Time	java.time.Instant, java.util.Date, java.time.LocalDate
Collections	List / ArrayList
Sets	Set, HashSet, LinkedHashSet, TreeSet
Maps	Map, HashMap, TreeMap
Other	Arrays, Enums, arbitrary Objects (via public no-args ctor + setters)

Install

Maven

<dependency>
  <groupId>io.github.oubaydos</groupId>
  <artifactId>java-random-generator</artifactId>
  <version>1.1.1</version>
  <scope>test</scope>
</dependency>

Gradle

gradletestImplementation("io.github.oubaydos:java-random-generator:1.1.1")

Artifact coordinates from Maven Central. Maven Repository

Quick start

import io.javarig.RandomInstanceGenerator;

RandomInstanceGenerator rig = new RandomInstanceGenerator();

// 1) Simple POJO
User user = rig.generate(User.class);

// 2) Generics (e.g., Map<String, Integer>)
java.util.Map<String, Integer> scores = rig.generate(Map.class, String.class, Integer.class);

// 3) Collections with exact size
java.util.List<String> names = rig.withSize(10).generate(ArrayList.class, String.class);

// 4) Collections with size range [min, max)
java.util.Set<Long> ids = rig.withSize(3, 7).generate(HashSet.class, Long.class);

// 5) Regex-constrained String
String phone = rig.withRegexPattern("[a-zA-Z0-9,;:!?]").generate(String.class);

// 6) Arrays & enums
Color[] palette = rig.withSize(4).generate(Color[].class);

API essentials

RandomInstanceGenerator

<T> T generate(Type objectType);
<T> T generate(Type objectType, Type... genericTypes);
RandomInstanceGenerator withSize(int size);                  // exact size
RandomInstanceGenerator withSize(int minSizeInclusive, int maxSizeExclusive);
RandomInstanceGenerator withRegexPattern(String regex);
RandomInstanceGenerator withOneTimeConfig(Configuration cfg);

• Use withSize(...) to control sizes for arrays/collections/strings for the next generation only (one-time config).
• withRegexPattern(...) constrains String values for the next generation.
• Cycles in object graphs cause NestedObjectRecursionException.

Requirements & limitations

• POJO generation expects a public no-args constructor and public setters for fields to populate.
• The generator keeps an internal stack to detect recursion; mutating and not thread-safe → create a generator per thread if needed.
• Regex support is a practical subset; unsupported tokens are sanitized before use.
• Defaults (e.g., size ranges) come from Configuration; override with withSize(...).

Why JavaRIG?

It’s a tiny dependency that does the basics well handy for tests and fakes without bringing a heavyweight fixture library.

Roadmap

• More built-in generators (BigDecimal, UUID, etc.)
• Thread-safe mode
• Public extensibility for custom TypeGenerators

Contributing

Issues and PRs welcome. Keep changes small and covered by tests. (See repo issues.) GitHub

License

MIT. See LICENSE. GitHub

Links

• Repo: github.com/oubaydos/javaRIG GitHub
• Maven Central artifact page: io.github.oubaydos:java-random-generator Maven Repository

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