Assertions

Nunit provides the Assert class to validate the expected result through many static methods.

Why do we need Assert:

To validate the expected result and the actual result we can use assert, it will throw an error if expected and actual mismatches.

There are constraint model of Assert,

Comparision
    - Equal
    - Not Equal
    - Greater than
    - Less than
    - Ranges
    

Examples:
            Assert.That(5, Is.EqualTo(5));
            Assert.That(4, Is.Not.EqualTo(5));
            Assert.That(6, Is.GreaterThan(5));
            Assert.That(4, Is.LessThan(5));
            Assert.That(4, Is.InRange(1,5));
 

String
    - String Equal
    - String Equal Ignore case
    - Substring
    - Empty
    - Start with, Ends with
    

Examples:
            Assert.That("Test", Is.EqualTo("Test"));
            Assert.That("Dev", Is.Not.EqualTo("Test"));
            Assert.That("Test", Does.Contain("Test"));
            Assert.That("Dev", Does.Not.Contain("Test"));
            Assert.That("", Is.Empty);
            Assert.That("Test", Is.Not.Empty);
            Assert.That("Test", Does.StartWith("T"));
            Assert.That("Dev", Does.Not.StartWith("T"));
            Assert.That("TesT", Does.EndWith("T"));
            Assert.That("Dev", Does.Not.EndsWith("T"));
            Assert.That("Test", Does.Match("T*T"));
 

Collection
    - Not Null
    - All Greater than
    - Instance of 
    - No Items
    - Exactly n items
    - Unique Items
    - Contains Items
    

Examples:
            int[] intArray = new int[] { 2, 4, 6, 8, 10 };
            int[] emptyArray = new int[] {};
            int[] nullArray = null;
            Assert.That(intArray, Is.All.Not.Null);
            Assert.That(intArray, Is.All.GreaterThan(1));
            Assert.That(intArray, Is.All.LessThan(11));
            Assert.That(emptyArray, Is.Empty);
            Assert.That(intArray, Is.Not.Empty);
            Assert.That(intArray, Has.Exactly(5).Items);
            Assert.That(intArray, Is.Unique);
            Assert.That(intArray, Contains.Item(4));
    
 

Conditional
    - Null 
    - Boolean
    - Empty
    

Examples:
            Assert.That(nullArray, Is.Null);
            Assert.That(true, Is.True);
            Assert.That(emptyArray, Is.Empty);
 

Compound
    - And
    - OR
    - Not      
    

Examples:
            Assert.That(3, Is.GreaterThan(2).And.LessThan(7));
            Assert.That(3, Is.LessThan(4).Or.GreaterThan(7));
            Assert.That(3, Is.Not.EqualTo(7));
            
 

File / Directory
     Examples:
            Assert.That(new FileInfo("path"), Does.Exist);
            
Exceptions
     - Is Exception Throws 
     Examples:
            Assert.That(Exceptionclass, Throws.Exception);

It also supports the classic way of asserting , 
     Assert.AreEqual("Test", "Dev");
     
If the script failed due to assertion then it will not move to the next line.

In such a situation we can use multiple asserts, Nunit will store all the failures and report at last.

If there is an unhandled exception occurred in Multiple asserts then the rest of the code will not be executed.