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Testing helps keep us from introducing a bug into our code, and it also helped us diagnose what the problem was.
We'll go into our test and
we'll copy our digraph test.
0:01
We'll change this to trigraph.
0:10
And we'll need a trigraphed word.
0:13
I'll use streak.
0:18
The expected output will be eakstray.
0:22
And let's run our test again.
0:27
As expected, our third test fails.
0:31
And we can see that it only moved
0:34
the first two letters
instead of the first three.
0:37
Back in our converter,
we'll start by adding our trigraph array.
0:42
Then we can add a new variable for
firstThreeLetters.
0:48
Substring, the word,
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start at the beginning, and
give the first three letters.
1:00
Next, we can copy our if
statement to create an else if.
1:04
We'll change to first, Three letters,
and first three letters.
1:11
Start at the third character,
and use our trigraph.
1:22
And now let's run our test again.
1:27
We get our same failure, but why?
1:30
Again, in our expected results,
compared to our actual results,
1:34
we see that only the first two
letters of streak has been moved.
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That's because we're checking for
digraphs first.
1:44
An ST is a digraph.
1:48
And STR is a trigraph.
1:50
Our test helps keep us from
introducing a bug into our code.
1:53
And it also help this diagnose
what the problem was.
1:58
We need to move our trigraph
check before our di-graph check.
2:02
Now let's run our test again.
2:16
And this time they all pass.
2:20
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