google/guava · error · ParameterNotInstantiableException

Cannot determine value for parameter %s of %s

Error message

Cannot determine value for parameter %s of %s

What it means

Thrown as ParameterNotInstantiableException by generateDummyArg() when, for a non-@Nullable constructor/factory parameter, FreshValueGenerator.generateFresh() returns null (no sample/default is registered for that parameter's type). The tester cannot even invoke the factory to begin testing, so it aborts that factory.

Source

Thrown at android/guava-testlib/src/com/google/common/testing/ClassSanityTester.java:687

          @Override
          @Nullable Object interfaceMethodCalled(Class<?> interfaceType, Method method) {
            return getDummyValue(TypeToken.of(interfaceType).method(method).getReturnType());
          }
        };
    for (Entry<Class<?>, Collection<Object>> entry : distinctValues.asMap().entrySet()) {
      generator.addSampleInstances((Class) entry.getKey(), entry.getValue());
    }
    return generator;
  }

  private static @Nullable Object generateDummyArg(Parameter param, FreshValueGenerator generator)
      throws ParameterNotInstantiableException {
    if (isNullable(param)) {
      return null;
    }
    Object arg = generator.generateFresh(param.getType());
    if (arg == null) {
      throw new ParameterNotInstantiableException(param);
    }
    return arg;
  }

  private static <X extends Throwable> void throwFirst(List<X> exceptions) throws X {
    if (!exceptions.isEmpty()) {
      throw exceptions.get(0);
    }
  }

  /** Factories with the least number of parameters are listed first. */
  private static <T> ImmutableList<Invokable<?, ? extends T>> getFactories(TypeToken<T> type) {
    List<Invokable<?, ? extends T>> factories = new ArrayList<>();
    for (Method method : type.getRawType().getDeclaredMethods()) {
      Invokable<?, ?> invokable = type.method(method);
      if (!invokable.isPrivate()
          && !invokable.isSynthetic()
          && invokable.isStatic()

View on GitHub (pinned to 94f39958ba)

Solutions

1. Register a default instance for the parameter type via ClassSanityTester.setDefault(Class, instance).
2. Mark the parameter @Nullable if null is a valid argument so the tester passes null instead of failing.
3. Provide a FreshValueGenerator sample or restrict the tested factories.

Example fix

// before
sanityTester.testNulls(MyService.class); // ctor takes Executor -> no default

// after
sanityTester.setDefault(Executor.class, Runnable::run);
sanityTester.testNulls(MyService.class);

sanityTester.setDefault(Executor.class, Runnable::run); // register default
sanityTester.testNulls(MyService.class);

try { sanityTester.testNulls(MyType.class); }
catch (ClassSanityTester.ParameterNotInstantiableException e) {
  // e.getMessage() names the parameter; register a default or mark @Nullable, retry
}

When it happens

Trigger: Calling ClassSanityTester.test*(...) on a class whose constructor or static factory has a parameter of a type with no known default (interface/abstract/third-party type) and not marked @Nullable. generateFresh returns null -> throw ParameterNotInstantiableException.

Common situations: Testing a value object that takes a collaborator interface in its constructor; types not covered by the built-in default value table; newly added factory parameters of exotic types.

Related errors

• Null check failed on return value of %s
• Serialization failed on return value of %s
• Cannot generate distinct value for parameter %s of %s
• unable to extract method from test: not a TestCase.
• Error extracting features from tester annotation.

AI-assisted analysis of google/guava@94f39958ba (2026-08-13). Data as JSON: /api/errors/5d01ab86da193bb3. Report an issue: GitHub.