package com.javatechie.tdd_example;

import org.junit.Assert;
import org.junit.Test;

/**
 * Unit test for simple App.
 */
public class PopulationSearchTest

{
	
	
	
	@Test
	public void findPopulation() {
		String city="Bangalore";
		int expectedPopulationCount=200000;
		PopulationSearch ps=new PopulationSearch();
		int count=ps.getPopulation(city);
		Assert.assertEquals(expectedPopulationCount, count);
	}
	
	@Test(expected=NullPointerException.class)
	public void findPopulationWithEmptyInput() {
		String city="";
		int expectedPopulationCount=0;
		PopulationSearch ps=new PopulationSearch();
		int count=ps.getPopulation(city);
		Assert.assertEquals(expectedPopulationCount, count);
	}
	
	@Test(expected=NullPointerException.class)
	public void findPopulationWithInavlidInput() {
		String city="XYZ";
		int expectedPopulationCount=0;
		PopulationSearch ps=new PopulationSearch();
		int count=ps.getPopulation(city);
		Assert.assertEquals(expectedPopulationCount, count);
	}
}

package com.javatechie.tdd_example;

import java.util.HashMap;
import java.util.Map;

/**
 * Hello world!
 *
 */
public class PopulationSearch {
	

	public int getPopulation(String city) {
		Map<String, Integer> populationMap = null;
		int populationCount = 0;
		if (city.isEmpty()) {
			throw new NullPointerException("input shouldn't be empty");
		}
		populationMap = getPopulationStatistic();
		if (!populationMap.containsKey(city)) {
			throw new NullPointerException("invalid input");
		} else {
			populationCount = populationMap.get(city);
		}
		return populationCount;
	}
	// user can give empty input
	// input may not be present in db

	private Map<String, Integer> getPopulationStatistic() {
		Map<String, Integer> populationMap = new HashMap<>();
		populationMap.put("Bangalore", 200000);
		populationMap.put("Hyderabad", 500000);
		populationMap.put("Pune", 300000);
		populationMap.put("Mumbai", 800000);
		return populationMap;
	}
}