CODEWITHSUNDEEP
javagradle
johnrl
johnrl

Reputation: 583

Gradle: how to test custom task output (println)

How would I go about testing the println output of custom Gradle tasks? This is my code so far:

class TaskTest {
    @Test
    void testSomething() {
        Project project = ProjectBuilder.builder().build()
        def task = project.task('testTask', type: Task)
        task.execute()
        <<assert task did println "Hello, world!">>
    }
}

Upvotes: 1

Views: 1563

Answers (2)

airborn
airborn

Reputation: 2625

You can do this by using SystemOutputInterceptor This should look something like this:

import groovy.ui.SystemOutputInterceptor

class TaskTest {
    @Test
    void testSomething() {
        def expected = 'expectedOutput'
        def actual ='';
        def interceptor = new SystemOutputInterceptor({ actual += it; false});

        Project project = ProjectBuilder.builder().build()
        def task = project.task('testTask', type: Task)

        interceptor.start()
        task.execute()
        interceptor.stop()

        assert actual.trim() == expected
    }
}

EDIT: If you would like to use spock for Your's than You could also test this like that:

class TaskTest extends spock.lang.Specification {
  def "should print test to stdout"() {
    given:
    def expected = 'expectedOutput'
    System.out = Mock(PrintStream)
    Project project = ProjectBuilder.builder().build()
    def task = project.task('testTask', type: Task)

    when:
    task.execute()

    then:
    1 * System.out.println(expected)
  }
}

mocking out System.out in Java should be possible with PowerMock

Upvotes: 1

Grzegorz Żur
Grzegorz Żur

Reputation: 49231

The solution is to replace standard output stream with your implementation and then read data from it. You can do it for error end input streams too.

def stdout = System.out
def os = new ByteArrayOutputStream()

System.out = new PrintStream(os)
println 'Hello World!' // implicit flush

def array = os.toByteArray()
def is = new ByteArrayInputStream(array)
System.out = stdout

def line = is.readLines()[0]
assert line == 'Hello World!'

Upvotes: 0

Related Questions