Junit Assertions

Beer.java

package com.github.jbleduigou.beer.model;

import com.fasterxml.jackson.annotation.JsonIgnore;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;

@AllArgsConstructor
@NoArgsConstructor
@Data
@Entity
public class Beer {

  @Id
  @GeneratedValue(strategy = GenerationType.IDENTITY)
  private Long id;

  private String name;

  private Double alcoholByVolume;

  @JsonIgnore
  public boolean isAlcoholFree() {
    return alcoholByVolume != null && alcoholByVolume <= 0.5;
  }

}

BeerRepository.java

package com.github.jbleduigou.beer.repository;

import com.github.jbleduigou.beer.model.Beer;

import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.stereotype.Repository;

@Repository
public interface BeerRepository extends JpaRepository<Beer, Long> {

  Beer findByName(String name);
}

BeerService.java

package com.github.jbleduigou.beer.service;

import com.github.jbleduigou.beer.exception.EntityNotFoundException;
import com.github.jbleduigou.beer.model.Beer;
import com.github.jbleduigou.beer.repository.BeerRepository;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import javax.validation.constraints.NotNull;

import java.util.List;
import java.util.stream.Collectors;

@Service
public class BeerService {

  private final BeerRepository repository;

  @Autowired
  public BeerService(BeerRepository repository) {
    this.repository = repository;
  }

  public List<Beer> getAllBeers() {
    return repository.findAll();
  }

  public List<Beer> getAllNonAlcoholicBeers() {
    return repository.findAll().stream()
            .filter(Beer::isAlcoholFree)
            .collect(Collectors.toList());
  }

  public Beer getBeerById(@NotNull Long beerId) {
    return repository.findById(beerId).orElseThrow(() -> new EntityNotFoundException("Beer", beerId));
  }
}