A little testing script can go a long way

General
1

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:

#!/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 :wink:

  • 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.
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