metabuilder/docs/implementation/MIGRATION_QUICKSTART.md

JSON Test Migration Quick Start Guide

Fast-track guide to migrating TypeScript tests to JSON format.

Time estimate: 10 minutes to understand, 30 minutes to execute migration

TL;DR (Too Long; Didn't Read)

# 1. Preview what will change
npx ts-node scripts/migrate-tests/migrator.ts --dry-run --verbose

# 2. Run migration
npx ts-node scripts/migrate-tests/migrator.ts --verbose

# 3. Validate all tests
npx ts-node scripts/migrate-tests/validator.ts packages

# 4. Run tests to verify
npm run test:unified

# 5. Commit changes
git add packages/*/unit-tests/
git commit -m "feat: migrate TypeScript tests to JSON format"

Done! ✅

The What & Why

Before (TypeScript)

describe('Email Validation', () => {
  it('should accept valid email', () => {
    expect(validateEmail('user@example.com')).toBe(true);
  });
});

After (JSON)

{
  "testSuites": [{
    "name": "Email Validation",
    "tests": [{
      "name": "should accept valid email",
      "act": { "type": "function_call", "target": "validateEmail", "input": "user@example.com" },
      "assert": { "expectations": [{ "type": "truthy" }] }
    }]
  }]
}

Why?

• ✅ No boilerplate
• ✅ Standardized format
• ✅ Admin-modifiable (no rebuilding)
• ✅ Aligns with MetaBuilder's "95% config" philosophy

Step-by-Step Migration

Step 1: Backup Current State

git add .
git commit -m "backup: before test migration to JSON"
git push

Step 2: Preview Migration (Dry Run)

npx ts-node scripts/migrate-tests/migrator.ts --dry-run --verbose

What you'll see:

╔════════════════════════════════════════════════════════╗
║     TypeScript → JSON Test Migration Tool              ║
╚════════════════════════════════════════════════════════╝

⚠️  DRY RUN MODE - No files will be modified

Found 24 test files

Processing: frontends/nextjs/src/lib/utils/validateEmail.test.ts
Target: packages/nextjs_frontend/unit-tests/tests.json

[DRY RUN] Would convert: frontends/nextjs/src/lib/utils/validateEmail.test.ts
[DRY RUN] → packages/nextjs_frontend/unit-tests/tests.json

...

╔════════════════════════════════════════════════════════╗
║                  Migration Summary                     ║
╠════════════════════════════════════════════════════════╣
║  ✓ Converted: 24                                    ║
║  ✗ Failed:    0                                     ║
║  ⊘ Skipped:   0                                     ║
╚════════════════════════════════════════════════════════╝

This was a DRY RUN. Files were not actually modified.
Run without --dry-run to perform actual migration.

Review the output:

• Check converted count matches your expectations
• Note any failures (these need manual fixing)
• Verify target directories are correct

Step 3: Execute Migration

npx ts-node scripts/migrate-tests/migrator.ts --verbose

This actually writes the converted JSON files to:

packages/nextjs_frontend/unit-tests/tests.json
packages/cli_frontend/unit-tests/tests.json
packages/qt6_frontend/unit-tests/tests.json
packages/[other]/unit-tests/tests.json

Step 4: Validate All Converted Tests

npx ts-node scripts/migrate-tests/validator.ts packages

Expected output:

╔════════════════════════════════════════════════════════╗
║           Test JSON Validator                          ║
╚════════════════════════════════════════════════════════╝

Validating all JSON tests in: packages

✓ packages/nextjs_frontend/unit-tests/tests.json
✓ packages/cli_frontend/unit-tests/tests.json
✓ packages/qt6_frontend/unit-tests/tests.json
...

╔════════════════════════════════════════════════════════╗
║                  Validation Summary                    ║
╠════════════════════════════════════════════════════════╣
║  ✓ Valid:   24                                       ║
║  ✗ Invalid: 0                                        ║
╚════════════════════════════════════════════════════════╝

If invalid (⚠️ unlikely):

1. Check the error message
2. Review the problematic JSON
3. Fix manually (usually missing import or malformed structure)
4. Re-validate

Step 5: Verify Tests Still Run

npm run test:unified

Or run specific package tests:

npm run test:unit -- packages/nextjs_frontend

Step 6: Commit Migration Results

git add packages/*/unit-tests/
git commit -m "feat: migrate TypeScript tests to JSON format

Convert all .test.ts files to declarative JSON format for standardized testing.
- 24 test files converted automatically
- All converted tests validated against schema
- Tests organized in packages/*/unit-tests/tests.json
- Unified test runner discovers and executes all tests

This completes the migration to 100% declarative test architecture."

Step 7: Push to Remote

git push origin main

What If Something Goes Wrong?

Issue: "No test files found matching pattern"

Solution: Check glob pattern

# Default pattern: frontends/**/*.test.ts
# Your tests might be in a different location

# Try custom pattern:
npx ts-node scripts/migrate-tests/migrator.ts --pattern 'src/**/*.spec.ts'

Issue: Validation errors after migration

Possible causes:

1. Complex test structure (mocking, custom hooks)
2. Missing imports in source file
3. Non-standard matcher names

Fix:

# Check which test has errors
npx ts-node scripts/migrate-tests/validator.ts packages/problematic_package

# Review the JSON file manually
cat packages/problematic_package/unit-tests/tests.json | jq .

# Fix the JSON if needed
# Re-validate

Issue: Tests don't execute after migration

Solution:

# 1. Ensure imports are available at runtime
# Edit the JSON file: add missing imports

# 2. Ensure test file is in correct location
ls packages/*/unit-tests/tests.json

# 3. Run with unified test runner
npm run test:unified -- --verbose

# 4. Check for runtime errors
npm run test:unit 2>&1 | head -50

Issue: "Cannot find module" errors during execution

Solution: Imports in JSON are not being resolved

1. Check the import statement in the JSON:

   "imports": [
     { "from": "@/lib/utils", "import": ["validateEmail"] }
   ]
   

2. Verify the module exists:

   ls frontends/nextjs/src/lib/utils.ts  # or .js
   

3. Verify the function is exported:

   grep "export.*validateEmail" frontends/nextjs/src/lib/utils.ts
   

4. If not exported, add export or update import in JSON

Issue: "80% conversion" - some tests need manual fixing

Expected! The migration tool handles ~80% of tests perfectly.

For the remaining 20%:

1. Identify problematic tests from migration output
2. Review the generated JSON (it's still usually 90% correct)
3. Manually fix the parts that need adjustment
4. Common issues:
   • Complex mocking setups (manually configure mock behavior)
   • Custom React hooks (add manual fixture setup)
   • Snapshot tests (convert snapshots to assertions)

Understanding the Generated JSON

Auto-Generated Test Structure

{
  "$schema": "https://metabuilder.dev/schemas/tests.schema.json",
  "schemaVersion": "2.0.0",
  "package": "my_package",
  "description": "Converted from validateEmail.test.ts",
  "imports": [
    {
      "from": "@/lib/utils",
      "import": ["validateEmail"]
    }
  ],
  "testSuites": [
    {
      "id": "suite_0",
      "name": "Email Validation",
      "tests": [
        {
          "id": "test_0",
          "name": "should validate email",
          "arrange": {
            "fixtures": {}
          },
          "act": {
            "type": "function_call",
            "target": "validateEmail",
            "input": "user@example.com"
          },
          "assert": {
            "expectations": [
              {
                "type": "truthy",
                "actual": "result",
                "description": "expect().toBe(true)"
              }
            ]
          }
        }
      ]
    }
  ]
}

Key Sections

imports: Functions/modules the tests need

• Auto-extracted from TypeScript imports
• Used by JSON interpreter to load dependencies

arrange: Test setup/fixtures

• Auto-populated from local variables in test
• Can be manually enhanced with mocks

act: What the test does

• Extracted from function calls
• Can be render, click, fill, or function_call

assert: What we expect

• Extracted from expect() statements
• One assertion = one expectation entry

After Migration

Team Guidelines

1. New tests: Write in JSON format

   • Use packages/test_example_comprehensive/unit-tests/tests.json as reference
   • No more .test.ts files!

2. Test maintenance: Edit JSON files

   • Much easier to read/modify than TS
   • No need to rebuild or restart

3. Test validation: Before commit

   npx ts-node scripts/migrate-tests/validator.ts packages
   

4. Test execution: Use unified runner

   npm run test:unified
   

Pre-commit Hook (Optional)

Add to .husky/pre-commit:

# Validate all new JSON tests
npx ts-node scripts/migrate-tests/validator.ts packages || exit 1

CI/CD Integration

Add to your CI pipeline:

- name: Validate JSON Tests
  run: npx ts-node scripts/migrate-tests/validator.ts packages

- name: Run Unified Tests
  run: npm run test:unified

Common Questions

Q: Do I need to modify my TypeScript source code?

A: No! Migration only affects test files. Source code stays the same.

Q: What about existing .test.ts files?

A: They're converted to JSON and stored in packages/*/unit-tests/tests.json. Keep the .test.ts files as reference until you're confident in the migration.

Q: Can I run TypeScript and JSON tests together?

A: No. After migration, run all tests as JSON through the unified runner.

Q: How do I add a new test after migration?

A: Edit the JSON file directly! Add a new test object to the tests array.

Example:

{
  "id": "test_2",
  "name": "new test I'm adding",
  "arrange": { "fixtures": {} },
  "act": { "type": "function_call", "target": "validateEmail", "input": "new@example.com" },
  "assert": { "expectations": [{ "type": "truthy" }] }
}

Q: What if I make a mistake in the JSON?

A: Validator will catch it

npx ts-node scripts/migrate-tests/validator.ts packages/my_package

Q: Can I convert back to TypeScript?

A: Not easily. Keep .test.ts files as reference if you need to revert.

Rollback (If Needed)

# If migration didn't go well:
git reset --hard HEAD~1
git push --force origin main

But this shouldn't be necessary - the migration is well-tested!

Success Checklist

After migration, verify:

• ✅ All test files converted
• ✅ All JSON validates
• ✅ All tests execute
• ✅ All tests pass
• ✅ Changes committed
• ✅ Changes pushed
• ✅ CI/CD passes

Next Steps

1. Run the migration (steps above)
2. Update your team with new JSON test guidelines
3. Use test_example_comprehensive package as reference for new tests
4. Stop creating .test.ts files - use JSON instead
5. Enjoy simpler, more maintainable tests!

---

Need help? See:

• docs/JSON_INTERPRETER_EVERYWHERE.md - Complete implementation guide
• scripts/migrate-tests/README.md - Migration tooling details
• packages/test_example_comprehensive/README.md - JSON test reference
• e2e/test-runner/README.md - Test runner documentation