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Background

ActivityPub § 5.8 Shares Collection:

Every object MAY have a shares collection.… The shares collection MUST be either an OrderedCollection or a Collection

About this Test

This is a Test describing a rule to determine whether an ActivityPub object has a shares property whose value conforms to a the requirement that "The shares collection MUST be either an OrderedCollection or a Collection".

Identifier

The identifier of this test is urn:uuid:b03a5245-1072-426d-91b3-a3d412d45ae8.

Test Subject

The subject of this test is data claiming to conform to the specification of an ActivityPub Object.

This test is not inherently applicable to an ActivityPub Server. An ActivityPub Server serves 1 or more ActivityPub Objects.

This test is not inherently applicable to a URL that resolves to an ActivityPub Object. The URL is not the same as the Object. The URL may resolve to different Objects in different contexts. Dereference the URL to test the referent with this test.

Inputs

This test requires the following inputs:

1. object - the object whose shares property will be tested
   • type: binary
   • constraints
     • will be interepreted as JSON

Applicability

This test applies to the the shares property on the input object.

This test does not apply to objects with more than one shares collection. If the input object has a shares property whose value is an array length >= 2, the test outcome is inapplicable.

This test does not apply to objects for which a shares collection cannot be found. If input object is not parseable as JSON to a JSON object, the test outcome is inapplicable. If input object is a JSON object, but it does not contain a property named shares, the test outcome is inapplicable.

Test Targets

1. shares - the shares collection derived from the input object and its shares property
   • because this is the value of a property from the input object that must be a JSON object, the value of this shares target will also be JSON
   • how to derive shares from inputs
     1. let inputs.object be the JSON object parsed from input object
     2. let propertyValue be
        • if inputs.object.shares is a JSON string, propertyValue is that string
        • if inputs.object.shares is a JSON object, propertyValue is that object
        • if inputs.object.shares is an Array of length 1, propertyValue is the item in that array
        • if inputs.object.shares is an Array of length greater than 1, the test outcome is inapplicable (covered in 'Applicability' above)
     3. let value be *if outboxValue is a json string, value is the result of interpreting that string as an ActivityPub Object Identifier, fetching the corresponding ActivityPub Object (e.g. GET https://...), and parsing the resulting response body as application/json. * otherwise value is outboxValue
     4. test target shares is equal to value

Expectations

1. shares is a JSON object
2. shares has a property named type
3. the values of the shares target's type property must indicate that the value is either an OrderedCollection or a Collection as determined by:
   • if the value of the shares target's type property is a string, it MUST be equal to either "OrderedCollection" or "Collection"
   • if the value of the shares target's type property is an Array, it MUST contain an entry for at least one of "OrderedCollection" or "Collection"

Assumptions

Interpreting "MUST be either an OrderedCollection or a Collection"

This test chose to interpret 'MUST be… an' to include 'indicate its type as'. The rationale is:

• it's easy to check and implement.
• I can't think of a better alternative
• I haven't received any objections

Test Cases

simple passed case

inputs

• object

  {
    shares: [{
      type: ["Collection"]
    }]
  }
  

test targets

• shares

  {
    "type": ["Collection"]
  }
  

  • outcome: passed

object.shares is a number

inputs

• object

  {
    shares: 1
  }
  

test targets

• shares

  1
  

  • outcome: failed
    • rationale: shares does not seem to "be either an OrderedCollection or a Collection"

object is number

inputs

• object

  1
  

result

• outcome: inapplicable

Glossary

outcome

An outcome is a conclusion that comes from evaluating a test on a test subject. An outcome can be one of the three following types:

• inapplicable: No part of the test subject matches the applicability
• passed: A test target meets all expectations
• failed: A test target does not meet all expectations

Requirements Mapping

• ActivityPub Requirement 937ae4e2-dd33-40c7-be1d-3ecac7f9fad5 - "The shares collection MUST be either an OrderedCollection or a Collection"
  • Required for Conformance to ActivityPub
  • Outcome Mapping
    • when test target shares has outcome passed, requirement is satisfied
    • when test target shares has outcome failed, requirement is not satisfied
    • when test target shares has outcome inapplicable, further testing is needed to determine requirement satisfaction

Change Log

• 2023-11-28T22:01:58.195Z - first draft
• 2023-12-29T23:06:48.611Z - format test cases section so each test case has a heading

Issues

• [ ] ff7a: expand applicability to cover objects with shares property whose value is an array of length >= 2
  • or perhaps just make another more ambitious test case