Learn C# Linq Examples

LinqLearn.cs

//These code are easily convertible into linq version try them out

using System;
using System.Collections.Generic;
using Microsoft.VisualStudio.TestTools.UnitTesting;
namespace UnitySC.PM.EME.Architecture.Test
{
    [TestClass]
    public class LinqDemoTests
    {
        List<Person> _people = new List<Person>()
        {
            new Person(54, "Henri"),
            new Person(34, "Berenice"),
            new Person(14, "Kevin"),
            new Person(56, "Josiane"),
            new Person(42, "Camille")
        };
        internal class Person
        {
            public int Age { get; set; }
            public string FirstName { get; set; }
            public Person(int age, string firstName)
            {
                Age = age;
                FirstName = firstName;
            }
            internal void SayHello() => Console.WriteLine("Hello");
        }
        [TestMethod]
        public void ForEach()
        {
            foreach (var person in _people)
            {
                person.SayHello();
            }
            Assert.IsTrue(true);
        }
        [TestMethod]
        public void Filter()
        {
            var adults = new List<Person>();
            foreach (var person in _people)
            {
                if (person.Age >= 18)
                {
                    adults.Add(person);
                }
            }
            Assert.AreEqual(4, adults.Count);
        }
        [TestMethod]
        public void Projection()
        {
            var namesAndAges = new List<string>();
            foreach (var person in _people)
            {
                namesAndAges.Add($"{person.FirstName} - {person.Age}");
            }
            var expectedNames = new List<string>() { "Henri - 54", "Berenice - 34", "Kevin - 14", "Josiane - 56", "Camille - 42" };
            CollectionAssert.AreEquivalent(expectedNames, namesAndAges);
        }
        [TestMethod]
        public void Reduction()
        {
            double average = 0;
            foreach (var person in _people)
            {
                average += person.Age;
            }
            average /= _people.Count;
            Assert.AreEqual(40, average);
            // Same with Count()
        }
        [TestMethod]
        public void Ordering()
        {
            int i = 0;
            Person olderPerson = new Person(0,"");
            do
            {
                if (_people[i].Age > olderPerson.Age)
                    olderPerson = _people[i];
                i++;
            } while (i < _people.Count);
            var expectedOlderPersonName = "Josiane";
            Assert.AreEqual(expectedOlderPersonName, olderPerson.FirstName);
        }
        [TestMethod]
        public void Verify()
        {
            bool anyAdult = false;
            foreach (var person in _people)
            {
                if (person.Age >= 18)
                {
                    anyAdult = true;
                }
            }
            Assert.IsTrue(anyAdult);
        }
    }
}