# A little testing script can go a long way

**URL:** <https://forum.codecrafters.io/t/a-little-testing-script-can-go-a-long-way/1574>\
**Category:** General\
**Tags:** challenge:grep\
**Created:** [August 31, 2024, 9:07pm UTC](https://forum.codecrafters.io/t/a-little-testing-script-can-go-a-long-way/1574 "2024-08-31T21:07:45Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![jasonflorentino](https://yyz1.discourse-cdn.com/flex003/user_avatar/forum.codecrafters.io/jasonflorentino/32/1059_2.png) [@jasonflorentino](https://forum.codecrafters.io/u/jasonflorentino)\
**Post date:** [August 31, 2024, 9:07pm UTC](https://forum.codecrafters.io/t/a-little-testing-script-can-go-a-long-way/1574/1 "2024-08-31T21:07:45Z")

</div>

I did this for working through the `grep` challenge and it meant I could refactor the app and add new features faster and with high confidence.

Admittedly the program just reads from stdin, and only exits 0 or 1, so it’s easy to write as many tests as you want for all the regex patterns your heart desires. (I didn’t bother writing automated tests when going through `http-server`.) So while this may not be worth it for all challenges, a quick and dirty test script might be useful for those wanting to re-test things more frequently, prevent regressions from a refactor, or make sure all cases are covered before hitting `git push`.

Here’s what I started with for the `grep` challenge:

```auto
#!/usr/bin/env bash

echo "Compiling program"

go build -o _temp/main cmd/mygrep/main.go

echo "Running tests..."

# This `expr AND expr OR expr` form takes
# advantage of short-circuiting to conditionally
# print the result of the test.
echo "aaabbbccc" | _temp/main -E "bc" && {
    echo "Passed"
} || {
    echo "Failed"
}

# Note that the messages must be flipped
# when we expect to find no match
 echo "aaabbbccc" | _temp/main -E "bcccc" && {
    echo "Failed"
} || {
    echo "Passed"
}

echo "Cleaning up"
rm -rf _temp

echo "Finished"

```

And as exercises for the reader 😉

- Print the inputs to see which tests are passing and failing.
- Print debugging help on failing cases. (I printed the command to run the program with the failing inputs along with my `--debug` flag.)
- Convert the test-running code into functions.
- Count up passes, fails, and total number of test cases.
- Add colors to more easily see pass vs. fail in the terminal output.