Greencently

Do you usually run your tests before you commit, to check your work?

Do your tests also get run by a pre-commit hook?

This is helpful in the worst case -- the pre-commit hook has your back when you forget -- but in the typical case it's harmful:

• Disrupts flow
• Doubles cost
• Adds no marginal benefit
• Discourages frequent small well-tested commits
• Engenders learned helplessness

We can fix this.

Setup for JUnit 5

1. Update build.gradle.kts:

dependencies {
    testRuntimeOnly("com.schmonz:greencently:CHECK_ABOVE_FOR_VERSION")
}
tasks.withType<Test> {
    maxParallelForks = 1  // see issue #4
}

2. Run all tests in your project
3. If green, see that .greencently/junit5 exists (and it's already .gitignore'd)
4. Run only one test, or only some tests, or all tests where at least one of them is red
5. See that .greencently/junit5 no longer exists
6. From now on, whenever you've just run tests, all of them, and they're all green, the pre-commit hook can decide not to run them again. Example:

#!/bin/sh

ACCEPTABLY_LARGE_NUMBER_OF_SECONDS_AGO=30

greencently() {
    too_many_seconds_ago=$1
    thenstamp=$(date -r .greencently/junit5 '+%s' 2>/dev/null || echo 0)
    nowstamp=$(date '+%s')
    secondsago=$(expr ${nowstamp} - ${thenstamp})
    [ ${secondsago} -lt ${too_many_seconds_ago} ]
}

if greencently ${ACCEPTABLY_LARGE_NUMBER_OF_SECONDS_AGO}; then
    ./gradlew clean build --exclude-task test
else
    ./gradlew clean build
fi

More information

See the Greencently webpage.