com.redfin.fuzzy

Interface Subcase<T>

public interface Subcase<T>

Describes a specific variant of a value generated by a Case. When the fuzzy engine is determining how many test cases to execute, it treats subcases as equivalency classes: although an individual subcase's return value can vary randomly, it assumes that all values it can return are effectively equal.

Method Summary

Modifier and Type	Method and Description
default void	describeTo(StringBuilder sink, T value) Describes a given output produced by this subcase, for use in test failure reports.
T	generate(Random random) Instructs the subcase to generate and return a new value.

Method Detail

generate

T generate(Random random)

Instructs the subcase to generate and return a new value.

Subcases are not required to return exactly the same value for subsequent calls to generate; they may randomly adjust their output on a per-call basis. However, subcases should adhere to the expectation that they represent an equivalency class of output: although individual return values may differ, each value they produce is effectively the same from a testing perspective.

If the subcase does chose to produce randomized values, it should do so deterministically: two calls provided with a random number generator with the same seed should produce exactly the same output. In general, this condition should be satisfied if the test uses the provided random number generator as its only source of randomness.

describeTo

default void describeTo(StringBuilder sink,
                        T value)

Describes a given output produced by this subcase, for use in test failure reports.

The default implementation of this method attempts to provide helpful descriptions of null, common primitives, strings, arrays, and collections. It defers to Object.toString() for all other descriptions.

Parameters:

sink - the string builder to which the description of the value should be appended.

value - the value (as returned by this subcase's generate method) that should be described.