diff --git a/Exam/Solution/Exam/SchoolSystem.Tests/Extensions/MoqExtensions.cs b/Exam/Solution/Exam/SchoolSystem.Tests/Extensions/MoqExtensions.cs
index 5a1b9f5..d7a2d9b 100644
--- a/Exam/Solution/Exam/SchoolSystem.Tests/Extensions/MoqExtensions.cs
+++ b/Exam/Solution/Exam/SchoolSystem.Tests/Extensions/MoqExtensions.cs
@@ -11,6 +11,14 @@ public static void SetupMany<TSvc, TReturn>(this Mock<TSvc> mock,
             params TReturn[] args)
             where TSvc : class
         {
+            if (args.Length == 0)
+            {
+                mock.Setup(expression)
+                    .Returns(null);
+
+                return;
+            }
+
             var numCalls = 0;
 
             mock.Setup(expression)
diff --git a/Exam/Solution/Exam/SchoolSystem.Tests/Models/StudentTests.cs b/Exam/Solution/Exam/SchoolSystem.Tests/Models/StudentTests.cs
index a393b54..b4d9a73 100644
--- a/Exam/Solution/Exam/SchoolSystem.Tests/Models/StudentTests.cs
+++ b/Exam/Solution/Exam/SchoolSystem.Tests/Models/StudentTests.cs
@@ -14,14 +14,15 @@ public void Constructor_ShouldSetGradeProperty_WhenInitialized()
         {
             var expectedGrade = Grade.Fifth;
             var student = new Student("Pesho", "Peshov", expectedGrade);
-            Assert.That(student.Grade == expectedGrade);
+            Assert.AreEqual(expectedGrade, student.Grade);
         }
 
         [Test]
         public void Constructor_ShouldSetInstanceToMarksCollectionProperty_WhenInitialized()
         {
             var student = new Student("Pesho", "Peshov", Grade.Fifth);
-            Assert.That(student.Marks != null);
+            Assert.AreNotEqual(null, student.Marks);
+
         }
 
         [Test]
diff --git a/Exam/Solution/Exam/SchoolSystem.Tests/Models/TeacherTests.cs b/Exam/Solution/Exam/SchoolSystem.Tests/Models/TeacherTests.cs
index 7185876..be91135 100644
--- a/Exam/Solution/Exam/SchoolSystem.Tests/Models/TeacherTests.cs
+++ b/Exam/Solution/Exam/SchoolSystem.Tests/Models/TeacherTests.cs
@@ -17,7 +17,7 @@ public void Constructor_ShouldSetSubjectProperty_WhenInitialized()
         {
             var expectedSubject = Subject.Bulgarian;
             var teacher = new Teacher("Pesho", "Peshov", expectedSubject);
-            Assert.That(teacher.Subject == expectedSubject);
+            Assert.AreEqual(expectedSubject, teacher.Subject);
         }
 
         [TestCase("P", "Goshev")]
@@ -45,8 +45,8 @@ public void AddMark_ShouldAddMarkToThePassedStudent_WhenPassedMarkIsValid()
 
             teacher.AddMark(student.Object, expectedValue);
 
-            Assert.That(student.Object.Marks.Single().Subject == expectedSubject);
-            Assert.That(student.Object.Marks.Single().Value == expectedValue);
+            Assert.AreEqual(expectedSubject, student.Object.Marks.Single().Subject);
+            Assert.AreEqual(expectedValue, student.Object.Marks.Single().Value);
         }
 
         [Test]