At the end of the previous chapter, you saw that an exception was thrown when the model’s CreateTask method was called with the value "sleep" in the VerifyAddTasks test from T_TodoModels.cs.:
foreach (var taskName in GetTaskNames())
{
model.CreateTask(taskName);
}A breakpoint has been defined. Now, we’d like the foreach loop execution to pause only when taskName has this value.
To do this, right-click on the breakpoint’s red dot, and select Conditions:
We’re interested in two types of conditions – Conditional Expression and Hit Count:
The first allows the break condition to be defined, either when a boolean expression is true, or when its value has changed:
The expression taskName == “sleep” requires the debugger to stop when the value of taskName is equal to “sleep”:
Let’s look at another situation where we know which iteration of a loop to stop. You can use the second type of condition by indicating the number of times the debugger must pass the breakpoint before pausing execution:
In this example, it's set to pause before performing the fourth iteration of the breakpoint.
If you look at the unit test code, you’ll see that the GetTaskNames method, which returns the list of task names, sets the value “sleep” on the first and fourth iterations:
private IEnumerable<string> GetTaskNames()
{
yield return "sleep";
yield return "work";
yield return "play Diablo";
yield return "sleep";
}Thus, this sort of conditional breakpoint allows pausing on the last value “sleep”.
Let's recap!
In this chapter, you’ve seen how to tell the debugger to pause code execution with instructions and conditions. We have everything ready to pause execution just before calling the instruction that will trigger the exception we’ve been hunting down ever since the start of this course! 🤩
However, we don’t know what to do to get out of the paused debugger: the next chapter will explain in detail how to run the execution step by step.
