Generated duration strings are not valid about 30% of the time

[hxlnt]

Generated duration strings are often not valid.

To reproduce the issue:

Using https://json-schema-faker.js.org/ with the following schema, some results generated are valid and others are not.

{
  "properties": {
    "duration": {
      "type": "string",
      "format": "duration"
    }
  },
  "required": [
    "duration"
  ],
  "additionalProperties": false
}

Clicking "Generate" 10 times yielded the following results--7 valid durations and 3 non-valid durations:

{
  "duration": "P78187143M"
}
{
  "duration": "P35882228342MT"
}
{
  "duration": "PW"
}
{
  "duration": "P05Y6D"
}
{
  "duration": "P15267M03035361D"
}
{
  "duration": "P26Y411240M"
}
{
  "duration": "P41Y7252451M9DT2590M"
}
{
  "duration": "P"
}
{
  "duration": "P69Y251M188D"
}
{
  "duration": "PT26540H"
}

Here is a comparison of the Regex used in

json-schema-faker/src/lib/generators/coreFormat.mjs

Line 26 in 7446c2f

duration: '^P(?!$)((\\d+Y)?(\\d+M)?(\\d+D)?(T(?=\\d)(\\d+H)?(\\d+M)?(\\d+S)?)?|(\\d+W)?)$',

against these results. As you can see, duration strings ending in T are not valid as well as strings without any duration values (e.g., P and PW)

I discovered this issue via Prism, where API response validation checks are failing against generated data. I initially logged stoplightio/prism#2650 against Prism, but it looks like this is actually a bug on json-schema-faker.

[pateketrueke]

Good catch, I think we should improve the regex used or the generation behavior, I'll see what to do asap, thank you!