I have only proven it correct, not tried it.

You see this is the initial test.

Welcome back again. This is the second unit in the debugging course.

The correct answer is No.

So here comes the quiz.

This is how the argument goes.

In the next unit, I'm going to introduce you to one of the most powerful debugging tools ever invented, that is assertions.

While you can easily roll out your own assertion, built in assertions typically do have a couple of advantages.

You see the location here it's in the file foo.c in line 9.

At the very end, what you see here, is an error message.

That is statements in the program that automatically check for errors during execution.

What you do instead is you put the functionality into code that is outside of the assertion and then use the assertion only for checking the result.

Now I have gone and fixed the program.

Here are some points to consider. First, failing is better than bad data.

So any proof can only be as good as the specification it relies on.

In Java, there is an option ea for enable assertions which turns assertions on.

In C C , the compiler option DNDEBUG for no debugging also turns assertions off.

The precondition for a sorting function is simple basically, we simply assume that x is a list.

Not very surprisingly, the assert keyword in Java is the least frequently used of all keywords in Java, which in my view is a big, big shame.

Which of these four is the best option to go down here considering the pros and cons about assertion that we see over to you.

Here's a failing assertion 2 2 5. Let's see, when we run this whole thing what we got?

The answer here is to first leave the assertions on then measure which assertions actually do impact performance and possibly do turn this off and leave the others enabled.

Data invariants make up an important part of all sorts of pre and postconditions.

Do you get the failing assertion condition. In our case, 2 2 5.

From the line of our reasoning, we can now deduce that if this condition had not been true, then for this input the assertion would not have failed.

If debugging were a video game and you would be hunted by bugs, then assertions would be a power pill that would help you catch all the bugs.

In Python, there is a O option which turns assertions off. O stands for optimized.

There is location that tell you where the assertion failed that is where in the code.

We get the location line 1 in our function and we get the list of callers.

The earlier you see an infection for instance, because an assertion fails, the shorter the cause effect chain, we need to investigate.

We also check this condition, but since we don't have any quotes in there, this line is never executed, and, of course, we add individual characters.

And everything, including the tag characters up here, is being added to the output.

Now imagine what happens if you do have assertions in your code that check large parts of your state for whether they're valid or not.

This is why assertions can be turned off.

First we need to generate on execution and second we need to check the outcome.

However, it suffices to set only a subset of these variables to the values found in the failing run.

They are optional meaning that they can be turned on or off although turning assertions off is mostly a bad idea, which we will discuss later.

The way assertions are being turned on and off differs from the language used.

These two kinds of assertions form a pair and both of them have very specific objectives.

But in our deduction, none of these matter.

Which, of course, again is a call for good assertions.

Assertions in the code are there to stay.

We could have the assertion in here, assert fault, which would be nice but keep in mind that this could actually also be turned off, for instance, when invoking the Python interpreter with 0.

However, if we assume the 2 2 5, we can run this and we get an assertion error that's being raised in here, and this gives us almost the same functionality as the built in assertions.

Just for the record, on my machine at this point, I can go and run a million test like this per second, which means that assertions can be a really great test device, compared that to the time it would take you to write a million number of test cases, which means that once you do have assertions, you can go and run test like crazy.