CI/CD pipeline setup in Deno - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

Understanding Deno CI Pipeline Step Output

Given this Deno CI pipeline step configuration, what will be the output of the deno test command if all tests pass successfully?

Deno

steps:
  - name: Run tests
    run: deno test --unstable --allow-net

A All tests passed. 0 failures.

B Error: Permission denied for network access.

C SyntaxError: Unexpected token in test file.

D No tests found to run.

💡 Hint

Think about what happens when tests run successfully with correct permissions.

The command deno test --unstable --allow-net runs tests with network permission. If all tests pass, the output confirms zero failures.

❓ Configuration

intermediate

Correct YAML for Deno CI Pipeline with Cache

Which YAML snippet correctly sets up a Deno CI pipeline step that caches the deno_dir directory to speed up dependencies installation?

A

steps:
  - uses: actions/cache@v3
    with:
      path: ./cache/deno_dir
      key: ${{ runner.os }}-deno-cache
  - run: deno cache main.ts

B

steps:
  - uses: actions/cache@v3
    with:
      path: ./deno_dir
      key: ${{ runner.os }}-deno-cache
  - run: deno cache main.ts

C

steps:
  - uses: actions/cache@v3
    with:
      path: ~/.deno
      key: ${{ runner.os }}-deno-cache
  - run: deno cache main.ts

D

steps:
  - uses: actions/cache@v3
    with:
      path: ~/.cache/deno
      key: ${{ runner.os }}-deno-cache
  - run: deno cache main.ts

💡 Hint

Deno stores cache in a hidden directory inside the user's home cache folder.

Deno caches dependencies in ~/.cache/deno. Caching this directory speeds up builds by reusing downloaded modules.

❓ Troubleshoot

advanced

Diagnosing Permission Error in Deno CI Pipeline

A Deno CI pipeline step runs deno run server.ts but fails with the error: PermissionDenied: network access is not allowed. What is the most likely cause?

A The <code>--allow-net</code> flag was not included in the run command.

B The <code>server.ts</code> file has syntax errors preventing execution.

C The <code>deno run</code> command requires <code>--unstable</code> flag for network access.

D The CI environment does not support network access at all.

💡 Hint

Check if the command includes the correct permission flags.

Deno requires explicit permission flags like --allow-net to allow network access. Missing this flag causes the permission error.

🔀 Workflow

advanced

Order of Steps in a Deno CI/CD Pipeline

What is the correct order of steps in a Deno CI/CD pipeline to ensure code quality and deployment?

A 2,3,1,4

B 2,1,3,4

C 1,2,3,4

D 3,2,1,4

💡 Hint

Think about caching before running tests to speed up dependency loading.

First cache dependencies to speed up installs, then run tests to verify code, then build, and finally deploy.

✅ Best Practice

expert

Best Practice for Secrets Management in Deno CI/CD Pipelines

Which option describes the best practice for managing secrets like API keys in a Deno CI/CD pipeline?

A Commit secrets in the source code repository but restrict access to trusted team members.

B Store secrets directly in the pipeline YAML file as plain text for easy access.

C Use encrypted secrets storage provided by the CI platform and inject them as environment variables.

D Pass secrets as command line arguments in the run step to keep them visible in logs.

💡 Hint

Think about security and avoiding exposure of sensitive data.

Using encrypted secrets storage and environment variables keeps secrets secure and avoids accidental exposure.

Practice

1. What is the main purpose of setting up a CI/CD pipeline for a Deno project?

easy

A. To automate testing and deployment processes

B. To write code faster manually

C. To increase the size of the project files

D. To disable automatic updates

Solution

1. Step 1: Understand CI/CD pipeline purpose

   A CI/CD pipeline automates repetitive tasks like testing and deployment to save time and reduce errors.

2. Step 2: Match purpose to options

   Only To automate testing and deployment processes describes automation of testing and deployment, which is the main goal.

3. Final Answer:

   To automate testing and deployment processes -> Option A

4. Quick Check:

   CI/CD automates testing and deployment = A [OK]

Hint: CI/CD means automating build, test, and deploy steps [OK]

Common Mistakes:

• Thinking CI/CD is about writing code manually
• Confusing CI/CD with increasing file size
• Believing CI/CD disables updates

2. Which of the following is the correct command to run tests in a Deno CI/CD pipeline?

easy

A. deno test

B. deno run test

C. deno build test

D. deno deploy test

Solution

1. Step 1: Recall Deno test command

   The official command to run tests in Deno is deno test.

2. Step 2: Compare options with correct syntax

   Only deno test matches the correct command syntax for running tests.

3. Final Answer:

   deno test -> Option A

4. Quick Check:

   Run tests with 'deno test' = A [OK]

Hint: Use 'deno test' to run tests, not 'deno run test' [OK]

Common Mistakes:

• Using 'deno run test' which runs a script, not tests
• Confusing build or deploy commands with test command
• Adding extra words like 'build' or 'deploy' incorrectly

3. Given this CI step in a Deno pipeline:

steps:
  - name: Run tests
    run: deno test --unstable
  - name: Bundle code
    run: deno bundle mod.ts bundle.js

What will be the result if tests fail?

medium

A. The pipeline skips tests and bundles code

B. The pipeline stops and does not bundle the code

C. The pipeline continues and bundles the code anyway

D. The pipeline deletes the bundle.js file

Solution

1. Step 1: Understand default pipeline behavior on failure

   In most CI/CD systems, if a test step fails, the pipeline stops to prevent deploying broken code.

2. Step 2: Apply to given steps

   If deno test --unstable fails, the next step to bundle code will not run.

3. Final Answer:

   The pipeline stops and does not bundle the code -> Option B

4. Quick Check:

   Failed tests stop pipeline = C [OK]

Hint: Failed tests usually stop pipeline to avoid bad deploys [OK]

Common Mistakes:

• Assuming pipeline continues after test failure
• Thinking tests are skipped automatically
• Believing files get deleted on test failure

4. You wrote this pipeline step:

steps:
  - name: Bundle code
    run: deno bundle mod.ts -o bundle.js

But the pipeline fails with an error. What is the likely cause?

medium

A. The pipeline requires 'deno test' before bundling

B. The file 'mod.ts' does not exist

C. The 'run' keyword is misspelled

D. The '-o' flag is not valid for 'deno bundle'

Solution

1. Step 1: Check 'deno bundle' syntax

   The correct syntax to specify output file is: deno bundle input.ts output.js without '-o' flag.

2. Step 2: Identify error cause

   Using '-o' causes an error because 'deno bundle' does not support it.

3. Final Answer:

   The '-o' flag is not valid for 'deno bundle' -> Option D

4. Quick Check:

   Output file is positional, no '-o' flag = D [OK]

Hint: Use positional output filename, not '-o', with deno bundle [OK]

Common Mistakes:

• Adding '-o' flag like other bundlers
• Assuming file existence without checking
• Thinking 'run' keyword is wrong
• Believing tests must run before bundling always

5. You want to create a CI/CD pipeline that runs tests, bundles code, and then deploys only if tests pass. Which YAML snippet correctly represents this sequence?

hard

A. steps:
- run: deno bundle mod.ts bundle.js
- run: deno test
- run: deploy.sh

B. steps:
- run: deploy.sh
- run: deno test
- run: deno bundle mod.ts bundle.js

C. steps:
- run: deno test
- run: deno bundle mod.ts bundle.js
- run: deploy.sh

D. steps:
- run: deno test
- run: deploy.sh
- run: deno bundle mod.ts bundle.js

Solution

1. Step 1: Determine correct order for CI/CD steps

   Tests must run first to verify code, then bundle code, then deploy if tests pass.

2. Step 2: Match order with options

   Only steps: - run: deno test - run: deno bundle mod.ts bundle.js - run: deploy.sh runs tests first, then bundles, then deploys.

3. Final Answer:

   Tests first, then bundle, then deploy -> Option C

4. Quick Check:

   Test -> Bundle -> Deploy = B [OK]

Hint: Test first, then bundle, then deploy in pipeline steps [OK]

Common Mistakes:

• Deploying before tests run
• Bundling before tests
• Changing step order incorrectly