Validation & Debugging

6 min read · Beginner
You will learn
  • How to read a YAML error message line-by-line
  • How to validate your file before handing it to a tool
  • A 60-second pre-flight checklist you can apply to any file

When working with YAML files in semiconductor design, even small mistakes can cause big problems. A missing space or wrong indentation might prevent your design tools from running correctly. In this lesson, you will learn tools and techniques to catch errors early.

Exercise: Validate a Real Semiconductor Config

Let’s examine a real configuration file and identify all the issues. This file from the book has 8 errors — missing spaces, wrong indentation, duplicate keys, and inconsistent booleans. Click each line to check it:

Interactive: Find All the Errors

This semiconductor config has 8 errors. Click each line to check it — can you find them all?

Found 0 of 8 errors
Broken File — click each line
1 # Semiconductor Design Configuration
2 project_info:
3 name: 5G Modem Design
4 team_lead:"Sarah Chen"
5 version: 2.0
6 version: 3.0
 
8 specifications:
9 - frequency_ghz: 2.4
10 - power_consumption_mw:150
11 - voltage_v: 0.8
 
13 testing:
14 functional_test: TRUE
15 performance_test: yes
16 power_test: True
Explanations
Click any line on the left to check if it has an error.

Error Messages and What They Mean

When YAML finds an error, it shows a message. These messages can be confusing at first, but they all point to common problems. Click each one to learn what it means:

Q "mapping values are not allowed here" ▸
Q "found duplicate key" ▸
Q "expected <block end>, but found '<scalar>'" ▸
Q "could not find expected ':'" ▸

How to Validate Your YAML

Method 1: Online YAML Validators

The easiest way to check your YAML — no installation needed:

  1. YAML Lint (yamllint.com) — paste your YAML, see errors instantly
  2. YAML Validator (codebeautify.org/yaml-validator) — validates and formats
  3. JSON Formatter YAML Validator — shows the JSON equivalent

Steps:

  1. Copy your YAML content
  2. Paste it into the validator
  3. Check for error messages
  4. Fix any issues reported

Method 2: Text Editor with YAML Support

Use editors that highlight YAML syntax errors in real time:

Recommended Editors:

  • Visual Studio Code (with YAML extension by Red Hat)
  • Sublime Text
  • Vim (with YAML plugin)

What to look for in your editor:

  • Red underlines (syntax errors)
  • Color coding (proper highlighting — keys, values, comments in different colors)
  • Indentation guides (vertical lines showing each level)

Method 3: Command Line Tools

If you have access to command line tools:

# Using yamllint (if installed)
yamllint my_config.yaml

# Using Python's yaml module
python -c "import yaml; yaml.safe_load(open('my_config.yaml'))"

Common Questions About Validation Tools

Q What is YAML Lint? ▸
Q What VS Code extension should I use? ▸
Q Can I validate from the command line? ▸

YAML Validation Checklist

Before using any YAML file, check these items:

Syntax Checklist

  • ✓ Indentation: Consistent spaces (2 or 4), no tabs
  • ✓ Colons: Space after every colon
  • ✓ Lists: Consistent dash formatting
  • ✓ Quotes: Used for text with spaces or special characters
  • ✓ Booleans: Using true/false (lowercase)
  • ✓ No duplicate keys in the same section

Content Checklist

  • ✓ Required fields: All necessary settings present
  • ✓ Valid values: Settings match expected formats
  • ✓ Units specified: Include units in key names (like frequency_mhz)
  • ✓ Comments helpful: Explain complex settings
  • ✓ Consistent naming: Follow snake_case naming

Building Good Validation Habits

Before Saving Your YAML File

  1. Visual inspection: Does the structure look right?
  2. Check indentation: Are all levels consistent?
  3. Validate syntax: Use an online validator
  4. Test with tools: Try loading it in your design tools

When Sharing YAML Files

  1. Include documentation: Explain the structure
  2. Validate first: Don’t share broken files
  3. Use version control: Track changes properly
  4. Include examples: Show how to use the configuration

Key takeaways

Proper YAML validation helps you:

  • ✓ Avoid tool errors: Prevent design tools from failing
  • ✓ Save debugging time: Catch mistakes early
  • ✓ Share confidently: Know your files work correctly
  • ✓ Maintain quality: Keep professional standards
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