All language subtitles for 385 Testing edge cases by writing and fixing failing tests.en

In the last video we added our new test to our state validator and in general one of the goals of the

unit testing is that we should test our objects with all possible inputs.

And while these may not be practical in all cases I think there is one more test that we could add to

this file and that is to check what happens when we pass a no string to this method.

However when we created the known empty string validator we haven't actually decided what should happen

when the input string is no.

So by writing these extra test we are actually looking at one edge case that we have not considered

before and we could approach this in two ways.

We could say that passing a new string is not about this scenario and we would expect the app to throw

an assertion at runtime or we could decide that a new string should be accepted and that this method

to return false.

In this case.

And for this specific case I propose that we take the second option and we allow unknown string to be

passed.

So what we are going to do is throw out our new test by copy pasting the previous method like this and

here we can update that description to no string.

And we are going to pass no two is valid and we want the expectation to be false and then we can run

this test and in the console log we see that we get a narrow because we try to call is not empty on

unknown object.

So let's open the string money that are once again.

And here we can fix this by adding a check that says if value is no then return false like this and

then we can run the test once again

and this time we can see that the test has passed.

By the way this icon on Android Studio is still red but I have found that this is a bug in Android Studio

and we can tell that the test is passed because this check mark is green over here.

In summary we have written some tests for this class and this forced us to think about all the possible

inputs and in the process of doing this we have discovered a problem when passing new values and to

address this.

We have written a failing test first and then we have fixed our known empty string validate or class

which made our test go green again.

And this is a process that is often used when writing tests because we can start by writing a failing

test and then we can write the code that makes that test go green and the result of this is that our

code is more robust and it also has better test coverage so you can consider using this approach as

you write your own classes and tests.

Okay.

So let's continue on the next video.