
using Xunit;
namespace ConsoleApp {
    public class ProgramTests {
        [Fact(DisplayName = "Default constructor sets AccountNumber and Balance to 0")] 
        public void DefaultConstructor_SetsFieldsToZero() {
            var acc = new Account();
            Assert.True(acc.AccountNumber == 0 && acc.Balance == 0.0m, "Default constructor should set AccountNumber and Balance to 0");
        }

        [Fact(DisplayName = "Constructor with one parameter sets AccountNumber and Balance to 0.0m")] 
        public void OneParameterConstructor_SetsAccountNumberAndZeroBalance() {
            var acc = new Account(12345);
            Assert.True(acc.AccountNumber == 12345 && acc.Balance == 0.0m, "Constructor with one parameter should set AccountNumber, Balance to 0");
        }

        [Fact(DisplayName = "Constructor with two parameters sets AccountNumber and Balance correctly")] 
        public void TwoParameterConstructor_SetsBothFields() {
            var acc = new Account(67890, 500.75m);
            Assert.True(acc.AccountNumber == 67890 && acc.Balance == 500.75m, "Constructor with two parameters should set AccountNumber and Balance to given values");
        }

        [Fact(DisplayName = "Constructors use chaining; assignment logic is not duplicated")] 
        public void Constructors_UseChaining_NoDuplication() {
            // Use reflection to count number of assignments in constructors
            var type = typeof(Account);
            var ctors = type.GetConstructors();
            int assignmentCtorCount = 0;
            foreach (var ctor in ctors) {
                var methodBody = ctor.GetMethodBody();
                if (methodBody != null && methodBody.LocalVariables.Count > 0) {
                    assignmentCtorCount++;
                }
            }
            // Only one constructor should contain assignment logic
            Assert.True(assignmentCtorCount <= 1, "Only the two-parameter constructor should contain assignment logic. Others should use chaining.");
        }
    }
}

ProgramTests.cs

Master the art of building robust C# classes through hands-on drills and engaging theory. Explore constructors, encapsulation, access modifiers, static classes, and more, with real-world inspired challenges.

Dive into the world of constructors in C#. Learn how to initialize objects, use constructor overloading, and apply best practices for flexible class instantiation.

Explore the principles of class design, encapsulation, and how to protect and organize data using access modifiers.

Learn how to use static classes and members for shared data and utility functionality in C#.

Delve into advanced class construction topics: composition vs inheritance, and refactoring structs into classes for more complex scenarios.

Challenge: Chained Account Constructors

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