public void TestValidateBST()
{
// Arrange
// null case
BTNode <int> nullRoot = null;
// single node
BTNode <int> singleNode = new BTNode <int>(1);
// common case true
BTNode <int> commonCaseTrueRoot = new BTNode <int>(5);
commonCaseTrueRoot.Left = new BTNode <int>(2);
commonCaseTrueRoot.Left.Left = new BTNode <int>(1);
commonCaseTrueRoot.Left.Right = new BTNode <int>(3);
commonCaseTrueRoot.Right = new BTNode <int>(8);
commonCaseTrueRoot.Right = new BTNode <int>(6);
// common case false 1
BTNode <int> commonCaseFalseRoot1 = new BTNode <int>(3);
commonCaseFalseRoot1.Left = new BTNode <int>(1);
commonCaseFalseRoot1.Left.Left = new BTNode <int>(0);
commonCaseFalseRoot1.Left.Right = new BTNode <int>(4);
commonCaseFalseRoot1.Right = new BTNode <int>(5);
commonCaseFalseRoot1.Right.Left = new BTNode <int>(5);
commonCaseFalseRoot1.Right.Right = new BTNode <int>(7);
// common case false 2
BTNode <int> commonCaseFalseRoot2 = new BTNode <int>(4);
commonCaseFalseRoot2.Left = new BTNode <int>(2);
commonCaseFalseRoot2.Right = new BTNode <int>(6);
commonCaseFalseRoot2.Right.Left = new BTNode <int>(1);
// Act
bool nullRootResult = TreesAndGraphs.ValidateBST(nullRoot);
bool singleNodeResult = TreesAndGraphs.ValidateBST(singleNode);
bool commonCaseTrueResult = TreesAndGraphs.ValidateBST(commonCaseTrueRoot);
bool commonCaseFalseResult1 = TreesAndGraphs.ValidateBST(commonCaseFalseRoot1);
bool commonCaseFalseResult2 = TreesAndGraphs.ValidateBST(commonCaseFalseRoot2);
// Assert
Assert.IsFalse(nullRootResult);
Assert.IsTrue(singleNodeResult);
Assert.IsTrue(commonCaseTrueResult);
Assert.IsFalse(commonCaseFalseResult1);
Assert.IsFalse(commonCaseFalseResult2);
}