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package au.id.zancanaro.javacheck;
import au.id.zancanaro.javacheck.annotations.DataSource;
import au.id.zancanaro.javacheck.annotations.Property;
import au.id.zancanaro.javacheck.junit.Properties;
import org.junit.runner.RunWith;
import java.util.Optional;
import java.util.function.Function;
import static au.id.zancanaro.javacheck.Generator.pure;
import static au.id.zancanaro.javacheck.Generators.integer;
import static au.id.zancanaro.javacheck.Generators.oneOf;
import static org.junit.Assert.assertEquals;
@RunWith(Properties.class)
public class OptionalRulesTest {
@DataSource
public static Generator<Optional<Integer>> listOfIntegers = oneOf(
pure(Optional.empty()),
integer().map(Optional::of));
@DataSource
public static Generator<Function<Integer, Integer>> integerFunction =
oneOf(
integer().map(OptionalRulesTest::plusI),
integer().map(OptionalRulesTest::timesI),
integer().map(OptionalRulesTest::constantlyI));
@Property
public void flatMapIdentity(Optional<Integer> optional) {
assertEquals(optional, optional.flatMap(Optional::of));
}
@Property
public void mappingComposition(
Optional<Integer> optional,
Function<Integer, Integer> f,
Function<Integer, Integer> g) {
Optional<Integer> left = optional
.map(g)
.map(f);
Optional<Integer> right = optional
.map(x -> f.apply(g.apply(x)));
assertEquals(left, right);
}
@Property
public void mapIdentityIsIdentity(Optional<Integer> optional) {
Optional<Integer> mapped = optional.map(x -> x);
assertEquals(optional, mapped);
}
private static Function<Integer,Integer> plusI(final int i) {
return new Function<Integer, Integer>() {
@Override
public Integer apply(Integer integer) {
return i + integer;
}
@Override
public String toString() {
return "x -> x + " + i;
}
};
}
private static Function<Integer,Integer> timesI(final int i) {
return new Function<Integer, Integer>() {
@Override
public Integer apply(Integer integer) {
return i * integer;
}
@Override
public String toString() {
return "x -> x * " + i;
}
};
}
private static Function<Integer,Integer> constantlyI(final int i) {
return new Function<Integer, Integer>() {
@Override
public Integer apply(Integer integer) {
return i;
}
@Override
public String toString() {
return "x -> " + i;
}
};
}
}
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