ythirion

public class Addition_properties_with_vavr_test {

    private final int size = 10_000, tries = 100;

    @Test
    public void commutative() {
        Property.def("Addition is commutative")
                .forAll(Arbitrary.integer(), Arbitrary.integer())
                .suchThat((x, y) -> Calculator.add(x, y) == Calculator.add(y, x))
                .check(size, tries)

ythirion

@RunWith(JUnitQuickcheck.class)
public class Account_properties {
    @Property
    public void balance_should_be_decremented_of_the_amount(
            @From(AccountGenerator.class) Account account,
            @From(WithdrawGenerator.class) Withdraw withdraw) {

        withEnoughMoney(account, withdraw);
        withoutReachingMaxWithdrawal(account, withdraw);

ythirion

public class WithdrawGenerator extends Generator<Withdraw> {

    public WithdrawGenerator() {
        super(Withdraw.class);
    }

    @Override
    public Withdraw generate(SourceOfRandomness sourceOfRandomness, GenerationStatus generationStatus) {
        return new Withdraw(sourceOfRandomness.nextDouble(), new Date());
    }

ythirion

import io.vavr.control.Try;
import lombok.AllArgsConstructor;
import lombok.Getter;
import lombok.NoArgsConstructor;

@AllArgsConstructor
@Getter
public class Account {
    private final double balance;
    private final boolean isOverdraftAuthorized;

ythirion

import com.pholser.junit.quickcheck.Property;
import com.pholser.junit.quickcheck.runner.JUnitQuickcheck;
import org.junit.Assert;
import org.junit.runner.RunWith;

@RunWith(JUnitQuickcheck.class)
public class Addition_properties {
    @Property
    public void commutative(int randomX, int randomY) {
        int result1 = Calculator.add(randomX, randomY);

ythirion

<properties>
    <junit-quickcheck.version>0.9.1</junit-quickcheck.version>
</properties>

<dependency>
    <groupId>com.pholser</groupId>
    <artifactId>junit-quickcheck-core</artifactId>
    <version>${junit-quickcheck.version}</version>
    <scope>test</scope>
</dependency>

ythirion

private readonly PersonRepository personRepository;
private readonly ILogger logger;
private readonly TwitterService twitterService;

public PersonService(ILogger logger)
{
    this.logger = logger;
    personRepository = new PersonRepository();
    twitterService = new TwitterService();
}

ythirion

public void file_monad_example()
{
    GetLine()
        .Bind(ReadFile)
        .Bind(PrintStrln)
        .Match(success => Console.WriteLine("SUCCESS"),
                failure => Console.WriteLine("FAILURE"));
}

static Try<string> GetLine()

ythirion

[Fact]
public void fold_vs_reduce()
{
    //fold takes an explicit initial value for the accumulator
    //Can choose the result type
    var foldResult = List(1, 2, 3, 4, 5)
        .Map(x => x * 10)
        .Fold(0m, (x, s) => s + x); // 150m

    //reduce uses the first element of the input list as the initial accumulator value

ythirion

static Func<int, int, int> Multiply = (a, b) => a * b;
static Func<int, int> TwoTimes = par(Multiply, 2);

[Fact]
public void partial_app_example()
{
    Multiply(3, 4); // 12
    TwoTimes(9); // 18
}