Stage conditions with when directive in Jenkins - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

Output of a stage with a simple when condition

Given the following Jenkins pipeline snippet, what will be the output if the branch name is 'feature-xyz'?

Jenkins

pipeline {
  agent any
  stages {
    stage('Build') {
      when {
        branch 'main'
      }
      steps {
        echo 'Building on main branch'
      }
    }
  }
}

A The stage 'Build' will be skipped and no output from this stage

B The stage 'Build' will run and print 'Building on main branch'

C Pipeline will fail with a syntax error

D The stage 'Build' will run but print nothing

💡 Hint

Check the branch name condition in the when directive.

The when condition specifies the stage runs only on branch 'main'. Since the branch is 'feature-xyz', the stage is skipped.

🧠 Conceptual

intermediate

Understanding multiple conditions in when directive

Which of the following when conditions will cause the stage to run only if the branch is 'develop' and the build is triggered by a user?

A when { branch 'develop' && triggeredBy 'UserIdCause' }

B when { allOf { branch 'develop'; triggeredBy 'UserIdCause' } }

C when { anyOf { branch 'develop'; triggeredBy 'UserIdCause' } }

D when { branch 'develop' || triggeredBy 'UserIdCause' }

💡 Hint

Look for the condition that requires both checks to be true.

The allOf block requires all conditions inside to be true, so the stage runs only if branch is 'develop' and triggered by a user.

❓ Troubleshoot

advanced

Why does this when condition cause a syntax error?

Identify the error in this when directive snippet: when { branch == 'main' }

Jenkins

when {
  branch == 'main'
}

A The when block must be empty

B Missing quotes around 'main'

C The branch condition requires parentheses

D Using '==' inside when block is invalid syntax

💡 Hint

Check the correct syntax for branch condition in when directive.

The when directive uses a keyword style like branch 'main', not an expression with '=='. Using '==' causes syntax error.

🔀 Workflow

advanced

Order of evaluation in multiple when conditions

Given this when directive, in what order are the conditions evaluated? when { allOf { branch 'release' environment name: 'DEPLOY_ENV', value: 'prod' } }

A branch condition is checked first, then environment

B environment condition is checked first, then branch

C Both conditions are checked simultaneously

D Only the branch condition is checked

💡 Hint

Think about how allOf logically works in Jenkins when directive.

Jenkins evaluates conditions in the order written inside allOf, so branch is checked first, then environment.

✅ Best Practice

expert

Choosing the best when condition for skipping stages on pull requests

You want to skip a stage when the build is triggered by a pull request. Which when condition is the best choice?

A when { branch 'PR-*' }

B when { expression { return env.CHANGE_ID == null } }

C when { not { changeRequest() } }

D when { triggeredBy 'PullRequestCause' }

💡 Hint

Consider the official Jenkins way to detect pull requests.

The changeRequest() condition is designed to detect pull requests. Using not { changeRequest() } skips the stage on PR builds.