{
  "exercise": "phone-number",
  "version": "1.0.2",
  "cases": [
    {
      "description": "Cleanup user-entered phone numbers",
      "comments": [
        " Returns the cleaned phone number if given number is valid, "
      , " else returns nil. Note that number is not formatted,       "
      , " just a 10-digit number is returned.                        "
      ],
      "cases": [
        {
          "description": "cleans the number",
          "property": "clean",
          "phrase": "(123) 456-7890",
          "expected": "1234567890"
        },
        {
          "description": "cleans numbers with dots",
          "property": "clean",
          "phrase": "123.456.7890",
          "expected": "1234567890"
        },
        {
          "description": "cleans numbers with multiple spaces",
          "property": "clean",
          "phrase": "123 456   7890   ",
          "expected": "1234567890"
        },
        {
          "description": "invalid when 9 digits",
          "property": "clean",
          "phrase": "123456789",
          "expected": null
        },
        {
          "description": "invalid when 11 digits does not start with a 1",
          "property": "clean",
          "phrase": "21234567890",
          "expected": null
        },
        {
          "description": "valid when 11 digits and starting with 1",
          "property": "clean",
          "phrase": "11234567890",
          "expected": "1234567890"
        },
        {
          "description": "invalid when more than 11 digits",
          "property": "clean",
          "phrase": "321234567890",
          "expected": null
        },
        {
          "description": "invalid with letters",
          "property": "clean",
          "phrase": "123-abc-7890",
          "expected": null
        },
        {
          "description": "invalid with punctuations",
          "property": "clean",
          "phrase": "123-@:!-7890",
          "expected": null
        },
        {
          "description": "invalid with right number of digits but letters mixed in",
          "property": "clean",
          "phrase": "1a2b3c4d5e6f7g8h9i0j",
          "expected": null
        }
      ]
    }
  ]
}