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Background

ActivityPub § 5.2 Inbox:

The inbox is discovered through the inbox property of an actor's profile. The inbox MUST be an OrderedCollection.

About this Test

This is a Test Case describing a rule to determine whether an ActivityPub object has an inbox property that meets this requirement to 'be an OrderedCollection', meeting requirement 4edf6768-c751-448f-96ac-4ef44cb4291f

Identifier

The identifier of this test is urn:uuid:5e94d155-ed4a-4d71-b797-d7c387736ecf.

Test Subject

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

This test is not inherently applicable to an ActivityPub Server. An ActivityPub Server serves 0 or more Actor Objects. An ActivityPub Server for a big community might serve hundreds of ActivityPub Actor Objects. An ActivityPub Server for a single human may serve only that person's ActivityPub Actor Object.

This test is not inherently applicable to a URL of an Actor Object. The URL is not the same as the Actor Object. The URL may resolve to different Actor Objects in different contexts.

Inputs

This test requires the following inputs:

1. object - the object whose inbox property will be tested

   • type: binary
   • constraints
     • will be interpreted as JSON

2. time - amount of time allowed to run test. This is meant to configure the limit for how long this test will wait for network requests.

   • required: yes
   • example: T0.0021S
   • type: bytes
   • constraints
     • MUST be an RFC3339 dur-time

Applicability

This test applies to inbox objects linked to from the object input. Usually an actor will have one inbox, but there may be multiple.

This test does not apply to objects with more than one inbox . If the input object has an inbox property whose value is an array of length >= 2, outcome is inapplicable. (See issue #5102 below to track expanding the applicability)

If object is not parseable as JSON to a JSON object, outcome is inapplicable.

If object is a JSON object, but it does not contain a property named inbox, outcome is inapplicable. The rationale is that there is already a test acaacb5f-8f7e-4f28-8d81-c7955070a767 that can be used to determine if input object has an inbox property at all.

Test Targets

1. inbox - the value of the inbox property in the input object object
   • since the object object must be JSON for this test's applicability, the value of JSON.parse(actor).inbox must also be JSON
   • how to derive inbox from inputs
     1. let inboxValue be
        • if inputs.actor.inbox is a JSON string, inboxValue is that string
        • if inputs.actor.inbox is a JSON object, inboxValue is that object
        • if inputs.actor.inbox is an Array of length 1, inboxValue is the item in that array
        • if inputs.actor.inbox is an Array of length greater than 1, the test outcome is not applicable (covered in 'Applicability' above)
          • see issue #5102 below to track expanding the applicability to support inbox property values that are arrays with length greater than 1
     2. let inboxObject be
        • if inboxValue is a json object, inboxObject is that object
        • if inboxValue is a json string, inboxObject is the result of interpreting that string as an ActivityPub Object Identifier and fetching the corresponding ActivityPub Object (e.g. GET https://...).
     3. test target inbox is inboxValue

Expectations

1. inbox is a json object
2. inbox has a property named type
3. the values of the inbox's type property must contain "OrderedCollection", as determined by
   • if value of inbox's type property is a string, it MUST be "OrderedCollection"
   • if value of inbox's type property is an Array, it MUST contain an entry identical to "OrderedCollection"

Assumptions

Interpreting "MUST be an OrderedCollection"

Revisiting the background from above, ActivityPub says

The inbox is discovered through the inbox property of an actor's profile. The inbox MUST be an OrderedCollection.

"MUST be an OrderedCollection" is open to some interpretation here.

This test chose to interpret 'be an' to include 'indicate its type as'. The rationale is that it's easy to check and easy to implement.

Test Cases

simple valid inbox

inputs

• object

  {
    "inbox": {
      "id": "http://example.org/blog/",
      "type": "OrderedCollection",
      "name": "Martin's Blog"
    }
  }
  

  • note: this OrderedCollection is from Example 5 in activitystreams-core

test targets

• inbox

  • value:

    {
    "id": "http://example.org/blog/",
    "type": "OrderedCollection",
    "name": "Martin's Blog"
    }
    

  • outcome: passed

inbox is null

inputs

• object

  {
    "inbox": null
  }
  

test targets

• inbox

  • value:

    null
    

  • outcome: failed

    • rationale: inbox is not an OrderedCollection

inbox type array contains only Person

inputs

• object

  {
    "inbox": {
      "type": ["Person"]
    }
  }
  

test targets

• inbox

  • value:

    {
      "type": ["Person"]
    }
    

  • outcome: failed

    • rationale: inbox type is not OrderedCollection

object with no properties

inputs

• object

  {}
  

result

• outcome: inapplicable

object is not JSON

inputs

• object

  \0x123abc_intentionallyNotJson
  

result

• outcome: inapplicable

inapplicable because inbox has many values

inputs

• object

  {
    "inbox": ["https://example.com", "https://example.com"]
  }
  

test targets

• inbox

  • value:

    ["https://example.com", "https://example.com"]
    

  • outcome: inapplicable

    • rationale: inbox values that are arrays of length greater than 1 or inapplicable. See issue #5102 below to track expanding the applicability

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 4edf6768-c751-448f-96ac-4ef44cb4291f - The inbox MUST be an OrderedCollection
  • Required for Conformance to ActivityPub
  • Outcome Mapping
    • when test target inbox has outcome passed, requirement is satisfied
    • when test target inbox has outcome failed, requirement is not satisfied
    • when test target inbox has outcome inapplicable, further testing is needed to determine requirement satisfaction

Change Log

• 2023-11-15T01:18:34.191Z - first draft
• 2023-11-16T06:09:56.915Z - finish all sections in first draft
  • add test cases for passed outcome
  • add test cases for failed outcome
  • add test cases for inapplicable outcome
  • add requirements mapping for https://socialweb.coop/activitypub/requirements/4edf6768-c751-448f-96ac-4ef44cb4291f/
  • add a test case where inbox is a URI that is resolved to an OrderedCollection an the outcome is "passed"
• 2023-12-29T21:51:17.983Z - reformat test cases

Issues

• #01d2: resolving inbox url should use inputs.time and timeout
• #5102: expand applicability to handle cases where there are multiple inboxes