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Background ^?

ActivityPub § 5.3 Followers Collection:

Every actor SHOULD have a followers collection. This is a list of everyone who has sent a Follow activity for the actor, added as a side effect. This is where one would find a list of all the actors that are following the actor. The followers collection MUST be either an OrderedCollection or a Collection

About This Test

This is a Test Case describing a rule to determine whether an ActivityPub Object is in partial conformance with the following behaviors required by ActivityPub.

• requirement abef3a0a-d3c4-4dee-a320-b28837d0bcd8 - The followers collection MUST be either an OrderedCollection or a Collection

Identifier

The identifier of this test is urn:uuid:018c3e08-611f-7e56-9f45-2fe5e4877d4e.

Test Subject

The subject of this test is an ActivityPub Actor Object.

Input ^?

This test requires the following inputs indicating parts of the test subject:

1. object - the object whose followers property will be tested
   • type: binary
   • constraints
     • should be JSON

Applicability ^?

This test applies to each of the followers collections derived from the values of the property on object named followers.

Prerequisites

• object is a JSON object
• object JSON object has a property named followers

How to Derive Test Targets from Input

• let targets be a set
• let followersValues be the result of
  • if object.followers is an Array, return it
  • else return an Array whose only item is the value of object.followers
• for each item in followersValues
  • if item is a string
    • let itemFetched be the result of interpreting the string as an ActivityPub Object Identifier and fetching the corresponding ActivityPub Object.
    • add itemFetched to targets
  • else add item to targets
• return targets

Expectations ^?

For every target target

• target is a JSON object
• target has a property named type
• the values of the target's type property must be one of
  • an array containing the string "Collection"
  • an array containing the string "OrderedCollection"
  • the string "Collection"
  • the string "OrderedCollection"

Assumptions ^?

Test Cases ^?

What follows are some specific cases of applything this test.

Passed Example 1 - followers has type Collection

inputs

• object:

  {
    "followers": {
      "type": "Collection"
    }
  }
  

test targets

• {
    "type": "Collection"
  }
  

  • outcome: passed

Passed Example 2 - followers has type OrderedCollection

inputs

• object:

  {
    "followers": {
      "type": "OrderedCollection"
    }
  }
  

test targets

• {
    "type": "OrderedCollection"
  }
  

  • outcome: passed

Passed Example 3 - followers type includes OrderedCollection

inputs

• object:

  {
    "followers": {
      "type": ["FancyCollection", "OrderedCollection"]
    }
  }
  

test targets

• {
    "type": ["FancyCollection", "OrderedCollection"]
  }
  

  • outcome: passed
    • rationale
      • "FancyCollection" is not well-defined here, but this object still passes the test because at least one of the type property values is OrderedCollection and thus satisfies the requirement as interpreted.

Failed Example 1 - followers is a number

inputs

• object:

  {
    "followers": 1
  }
  

test targets

• 1
  

  • outcome: failed

Failed Example 2 - followers is an empty object

inputs

• object:

  {
    "followers": {}
  }
  

test targets

• {}
  

  • outcome: failed

Failed Example 3 - followers object type is array including only "Link"

inputs

• object:

  {
    "followers": {
      "type": ["Link"]
    }
  }
  

test targets

• {
    "type": ["Link"]
  }
  

  • outcome: failed

Inapplicable Example 1

inputs

• object:

  1
  

result

• outcome: inapplicable

Inapplicable Example 2 - object has no followers property

inputs

• object:

  { "foo": "bar" }
  

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 abef3a0a-d3c4-4dee-a320-b28837d0bcd8 - The followers collection MUST be either an OrderedCollection or a Collection
  • Required for Conformance to ActivityPub
  • Outcome Mapping
    • when every test target has outcome passed, the requirement is satisfied by the test subject
    • when any test target has outcome failed, the requirement is not satisfied by the test subject
    • when any test target has outcome inapplicable, further testing is needed to determine requirement satisfaction

Issues ^?

Change Log

• 2023-12-06T07:43:27.890Z - init
• 2023-12-18T05:11:09.722Z - add test cases based on implementing