public void OnlyReturnPositiveExpressionTypes()
{
// Arrange
var weighted = new WeightedExpressionTypeProvider();
foreach (ExpressionType type in Enum.GetValues(typeof(ExpressionType))) {
weighted.SetTypeDistribution(type, 0);
}
ExpressionType[] allowed = {
ExpressionType.Add,
ExpressionType.Subtract,
ExpressionType.Constant
};
foreach (ExpressionType type in allowed) {
weighted.SetTypeDistribution(type, 1);
}
// Act
// Assert
for (int i = 0; i < 10; i++) {
var expressionType = weighted.NextExpressionType();
bool typeFound = false;
foreach (ExpressionType type in allowed) {
if (expressionType == type) {
typeFound = true;
continue;
}
}
Assert.IsTrue(typeFound);
}
}
public void ShouldNotAllowNegativeWeight()
{
// Arrange
var weighted = new WeightedExpressionTypeProvider();
// Act
// Assert
weighted.SetTypeDistribution(ExpressionType.Subtract, -1);
}
public void TypeDistribution_SelectUnlikelyExpressionType()
{
// Arrange
var weighted = new WeightedExpressionTypeProvider();
foreach (ExpressionType type in Enum.GetValues(typeof(ExpressionType))) {
weighted.SetTypeDistribution(type, 0);
}
// Act
weighted.SetTypeDistribution(ExpressionType.Add, 100000000);
weighted.SetTypeDistribution(ExpressionType.Subtract, 0.00001);
var expressionType = weighted.NextExpressionType();
// Assert
Assert.AreEqual(ExpressionType.Add, expressionType);
}