fix: address non-digit character cases in card number validation

[Chethan-rao]

Type of Change

• [x] Bugfix
• [ ] New feature
• [ ] Enhancement
• [ ] Refactoring
• [ ] Dependency updates
• [ ] Documentation
• [ ] CI/CD

Description

This PR enforces following validations on the card number -

• non-digit characters in card number
• invalid card number length
• invalid card number (luhn failure)

If any of the above validation fails, appropriate error is raised. This PR also fixes the failing CI check.

Additional Changes

• [ ] This PR modifies the API contract
• [ ] This PR modifies the database schema
• [ ] This PR modifies application configuration/environment variables

Motivation and Context

How did you test it?

1. Unit tests -

2. Invalid card number length -

curl --location 'http://localhost:8080/payment_methods' \
--header 'Content-Type: application/json' \
--header 'Accept: application/json' \
--header 'api-key: dev_ekfmmqSYoY0bvjOGGO0Pe5CQdP9oS0ycImpRG78tjNTrgp03HGxvDAhHCrmHrYoO' \
--data '{
  "payment_method": "card",
  "payment_method_type": "credit",
  "payment_method_issuer": "Visa",
  "card": {
    "card_number": "1234567",
    "card_exp_month": "10",
    "card_exp_year": "26",
    "card_holder_name": "Chethan"
  },
  "customer_id": "cus_Cbszk87dvhH7EuBp2ZoB",
  "metadata": {
    "city": "NY",
    "unit": "245"
  }
}'

3. Non-digit character in card number

curl --location 'http://localhost:8080/payment_methods' \
--header 'Content-Type: application/json' \
--header 'Accept: application/json' \
--header 'api-key: dev_ekfmmqSYoY0bvjOGGO0Pe5CQdP9oS0ycImpRG78tjNTrgp03HGxvDAhHCrmHrYoO' \
--data '{
  "payment_method": "card",
  "payment_method_type": "credit",
  "payment_method_issuer": "Visa",
  "card": {
    "card_number": "411111111111111🦀",
    "card_exp_month": "10",
    "card_exp_year": "26",
    "card_holder_name": "Chethan"
  },
  "customer_id": "cus_Cbszk87dvhH7EuBp2ZoB",
  "metadata": {
    "city": "NY",
    "unit": "245"
  }
}'

4. Invalid card number (Failing luhn check):

curl --location 'http://localhost:8080/payment_methods' \
--header 'Content-Type: application/json' \
--header 'Accept: application/json' \
--header 'api-key: dev_ekfmmqSYoY0bvjOGGO0Pe5CQdP9oS0ycImpRG78tjNTrgp03HGxvDAhHCrmHrYoO' \
--data '{
  "payment_method": "card",
  "payment_method_type": "credit",
  "payment_method_issuer": "Visa",
  "card": {
    "card_number": "411111111111112",
    "card_exp_month": "10",
    "card_exp_year": "26",
    "card_holder_name": "Chethan"
  },
  "customer_id": "cus_Cbszk87dvhH7EuBp2ZoB",
  "metadata": {
    "city": "NY",
    "unit": "245"
  }
}'

Checklist

• [x] I formatted the code cargo +nightly fmt --all
• [x] I addressed lints thrown by cargo clippy
• [x] I reviewed the submitted code
• [x] I added unit tests for my changes where possible