Normally when we run tests in our Gradle build, all our tests are executed and at the end we can see which tests are failing. But what if we want to let the build fail at the first failing test? Especially for a large test suite this can save a lot of time, because we don’t have to run all (failing) tests, we immediately get informed that at least one test is failing.

We can do this by passing the command-line option --fail-fast when we run the test task in Gradle. With this option Gradle will stop the build and report a failure at the first failing test. Instead of passing the command-line option --fail-fast we can set the property failFast of the test task to true. Using the property failFast allows to still fail the build on the first failing test even if we for example run a build task that depends on the test task. The command-line option --fail-fast only works if we run the test task directly, not if it is part of the task graph for our build when we run another task.

In the following sample we have two failing tests in our project. When we run our test task we see this in the output of our Gradle build:

$ gradle test

mrhaki.gradle.GreetingSpec > greeting should return 'Hello' followed by input FAILED
    org.spockframework.runtime.SpockComparisonFailure at GreetingSpec.groovy:12

mrhaki.gradle.HelloSpec > message should return 'Hello' FAILED
    org.spockframework.runtime.SpockComparisonFailure at HelloSpec.groovy:12

2 tests completed, 2 failed

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':test'.
> There were failing tests. See the report at: file:///Users/mrhaki/Projects/mrhaki.com/blog/posts/samples/gradle/testfast/build/reports/tests/test/index.html

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.

* Get more help at https://help.gradle.org

BUILD FAILED in 1s
3 actionable tasks: 1 executed, 2 up-to-date

Now let’s run the test task with the command-line option --fail-fast:

$ gradle test --fail-fast -q

mrhaki.gradle.GreetingSpec > greeting should return 'Hello' followed by input FAILED
    org.spockframework.runtime.SpockComparisonFailure at GreetingSpec.groovy:12

2 tests completed, 2 failed

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':test'.
> There were failing tests. See the report at: file:///Users/mrhaki/Projects/mrhaki.com/blog/posts/samples/gradle/testfast/build/reports/tests/test/index.html

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.

* Get more help at https://help.gradle.org

BUILD FAILED in 1s
3 actionable tasks: 1 executed, 2 up-to-date

Although the totals indicate 2 tests completed, 2 failed when we use the fail fast option we can see in the output the test in the HelloSpec specification is not run this time.

Instead of using the command-line option --fail-fast we can set the property failFast in our test task, like in the following example Gradle build:

...
test {
   failFast = true
}
...

Written with Gradle 5.6.2.

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