Add Property parameter to Test-Json

Summary of the new feature / enhancement

On the back of #12272 in which since that was raised both Path and SchemaPath parameters have been added this request is to add a Property parameter that accepts a string array of properties to test for.

This is so that

Test-Json -Path .\test.json -SchemaPath .\schema.json -Property Time,Date,Location 

would perhaps return True if all 3 exist False if all 3 do not exist An object that that shows which exist and which do not exist that can be easily passed to any other downstream cmdlet or application

Proposed technical implementation details (optional)

No response

[gregsdennis]

If you only want to validate a subset of properties, you need to create a new schema that only contains those properties. Partial schema validation isn’t something that’s supported (by JSON Schema, not just this cmdlet).

For example, given the schema

{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "$id": "https://example.com/my-model",
  "type": "object",
  "properties": {
    "Time": { /* ... */ },
    "Date": { /* ... */ },
    "Location": { /* ... */ },
    "Foo": { /* ... */ }
  }
}

This will validate all four properties, always. There’s no way to perform a partial validation by ignoring Foo.

If you want to only validate Time, Date, and Location, then you’ll need to create a new schema that validates just those.

{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "$id": "https://example.com/my-selective-model",
  "type": "object",
  "properties": {
    "Time": { /* ... */ },
    "Date": { /* ... */ },
    "Location": { /* ... */ }
  }
}

If you still need a schema that validates the entire thing, you can reference this new one in the other:

{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "$id": "https://example.com/my-new-model",
  "$ref": "https://example.com/my-selective-model",
  "properties": {
    "Foo": { /* ... */ }
  }
}

This new schema will validate everything in my-selective-model with the addition of the Foo property.

[gregsdennis]

if support in other tooling chains offer partial validation in future or not

You’re welcome to perform a survey of the implementations, but I doubt you’ll find one that supports partial validation specifically because it’s not a feature of JSON Schema. Implementations tend to stick as closely to the spec as their language allows.

You’re also welcome to raise a proposal, but I can say with some confidence (because I’m one of the authors) that it probably won’t be. We aim to honor the intent of the schema author. If the schema author has elected to include/require properties, then that’s what needs to be validated. If something else needs to be validated, a different schema needs to be used.