Groovy syntax in pipelines in Jenkins - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

What is the output of this Groovy pipeline snippet?

Consider this Jenkins pipeline Groovy code snippet:

def result = []
for (int i = 1; i <= 3; i++) {
  result.add(i * 2)
}
println(result)

What will be printed in the Jenkins console?

Jenkins

def result = []
for (int i = 1; i <= 3; i++) {
  result.add(i * 2)
}
println(result)

A [1, 2, 3]

B SyntaxError

C [3, 6, 9]

D [2, 4, 6]

💡 Hint

Think about what the loop does for each value of i.

The loop runs from 1 to 3. For each i, it multiplies by 2 and adds to the list. So the list becomes [2, 4, 6].

❓ Configuration

intermediate

Which Groovy syntax correctly defines a Jenkins pipeline stage with a shell step?

Choose the correct Groovy syntax to define a Jenkins pipeline stage named Build that runs a shell command echo Hello.

A

stage('Build') {
  steps {
    shell 'echo Hello'
  }
}

B

stage('Build') {
  shell {
    echo 'Hello'
  }
}

C

stage('Build') {
  steps {
    sh 'echo Hello'
  }
}

D

stage('Build') {
  commands {
    sh 'echo Hello'
  }
}

💡 Hint

Remember the correct block names for steps and shell commands in declarative pipelines.

The correct syntax uses steps block and sh command to run shell scripts.

❓ Troubleshoot

advanced

What error does this Groovy pipeline code produce?

Analyze this snippet:

def x = 5
if (x = 10) {
  println('x is 10')
} else {
  println('x is not 10')
}

What error or output will Jenkins show?

Jenkins

def x = 5
if (x = 10) {
  println('x is 10')
} else {
  println('x is not 10')
}

A SyntaxError: Cannot assign in if condition

B Prints 'x is 10'

C Prints 'x is not 10'

D RuntimeException: Variable x not defined

💡 Hint

Check the difference between assignment = and comparison ==.

In Groovy, assignment = is allowed inside an if condition and returns the assigned value (10), which is truthy, so it prints 'x is 10'. Use == for comparison to avoid accidental assignment.

🔀 Workflow

advanced

Which Groovy pipeline snippet correctly waits for a user input before continuing?

In Jenkins pipelines, you want to pause and ask for user approval before proceeding. Which snippet does this correctly?

A input message: 'Approve deployment?', ok: 'Yes'

B pause('Approve deployment?')

C waitForInput('Approve deployment?')

D confirm('Approve deployment?')

💡 Hint

Look for the Jenkins pipeline step that pauses for input.

The input step pauses the pipeline and waits for user approval with a message and button label.

✅ Best Practice

expert

Which Groovy pipeline snippet best handles errors to ensure cleanup always runs?

Choose the snippet that guarantees the cleanup() function runs even if build() fails.

A

try {
  build()
} catch (e) {
  echo 'Build failed'
} finally {
  cleanup()
}

B

build()
cleanup()

C

try {
  build()
  cleanup()
} catch (e) {
  echo 'Build failed'
}

D

catch (e) {
  echo 'Build failed'
}
build()
cleanup()

💡 Hint

Think about how try-catch-finally works in Groovy.

The finally block always runs whether an error occurs or not, ensuring cleanup is done.