ZAP ("Ze'report Anything Protocol")

A streamable structured interface for real time reporting of developer tools.

Important! This specification is a work in progress and is seeking feedback from potential users and any developer tooling authors. It may change dramatically based on feedback.

Motivation

There are thousands of different developer tools across every programming language. Each of them has their own way of reporting the results of tests while they are running and after they are completed.

But we need some standard formats for reporting their results so that tools can work together without having to support hundreds of different formats for every language and tool.

Today there exists two prominent formats for reporting test results:

JUnit XML

<?xml version="1.0" encoding="UTF-8" ?>
<testsuites id="20140612_170519" name="New_configuration (14/06/12 17:05:19)" tests="225" failures="1262" time="0.001">
  <testsuite id="codereview.cobol.analysisProvider" name="COBOL Code Review" tests="45" failures="17" time="0.001">
    <testcase id="codereview.cobol.rules.ProgramIdRule" name="Use a program name that matches the source file name" time="0.001">
      <failure message="PROGRAM.cbl:2 Use a program name that matches the source file name" type="WARNING">
WARNING: Use a program name that matches the source file name
Category: COBOL Code Review – Naming Conventions
File: /project/PROGRAM.cbl
Line: 2
      </failure>
    </testcase>
  </testsuite>
</testsuites>

Test Anything Protocol (aka "TAP")

1..4
ok 1 - Input file opened
not ok 2 - First line of the input valid
ok 3 - Read the rest of the file
not ok 4 - Summarized correctly # TODO Not written yet

Each of these has different strengths and weaknesses.

JUnit is easy to parse and lots of structured information about results, but cannot be streamed as tests run. You have to wait until your tests are finished before generating the XML.

TAP is great for streaming test results as they run and can be used to report progress to developers. But it is hard to parse and contains very little structured information.

ZAP is a new reporting format that tries to get the best of both systems, it contains well structured information about results and can be streamed and parsed very easily.

Goals

• Streaming: Allow developer tools to report test information to consumers in real time as tests execute.
• Concurrency: Allow tools to be run concurrently across threads or processes and allow interweaving of events in output.
• Structured: Use a well-defined structure that is easy to parse and understand with lots of information.
• Definitive: At any given point, it should be clear what state things are in: "Passing" or "Failing". When a completion state is given, it should not change.
• Extensible: Have a clear way of adding additional information to output that is still meets the above goals.

Non-goals

• Readability: It should be easy to build reporting tools on top of ZAP that is human readable, but ZAP itself should be designed for machines.

Comparison

	XML	TAP	ZAP
Streaming	❌	✅	✅
Concurrency	N/A	👌	✅
Structured	✅	❌	✅
Extensible	✅	❌	✅
Readable	❌	✅	❌

Considerations

There are many different types of development tools that would like a standard way to report results via a format like ZAP.

They generally fall into one of two categories:

1. Producers

• Testing Frameworks
• Linters/Code Quality
• Type Checkers
• Compilers/Build Tools

2. Consumers

• CI/CD Platforms/Services
• Task Runners/Build Frameworks
• Reporters (CLI or GUI)

Many of these tools already use JUnit or TAP, however many are unhappy with these formats and would like something better. ZAP should consider all of these tools and provide guidance on implementations.

Spec

Format

The output is stream of events written in newline-delimited json:

{"kind":"group","event":"started","id":"0","time":304.09246500208974,"content":[{"message":"DatabaseConnection","source":[{"file":"/path/to/test.js","start":{"line":3,"column":6},"end":{"line":3,"column":26}}]}]}
{"kind":"item","event":"started","id":"0.0","time":318.4295700006187,"content":[{"message":"db.connect()","source":[{"file":"/path/to/test.js","start":{"line":4,"column":8},"end":{"line":4,"column":20}}]}]}
{"kind":"check","event":"failed","id":"0.0.0","time":379.8125419989228,"content":[{"message":"Expected:\n { port: 5432 }\nActual:\n  { port: 8000 }","source":[{"file":"/path/to/test.js","start":{"line":42,"column":6}}]}]}
{"kind":"item","event":"failed","id":"0.0","time":390.98526199907064,"content":[{"message":"db.connect()","source":[{"file":"/path/to/test.js","start":{"line":4,"column":8},"end":{"line":4,"column":20}}]}]}
{"kind":"group","event":"failed","id":"0","time":464.20705600082874,"content":[{"message":"DatabaseConnection","source":[{"file":"/path/to/test.js","start":{"line":3,"column":6},"end":{"line":3,"column":26}}]}]}

Individual events have this shape:

interface Event {
  kind: string,
  event: string,
  id: string,
  time: number,
  status?: string,
  content: Array<{
    message: string,
    source?: Array<{
      file: string,
      start?: { line: number, column?: number },
      end?: { line: number, column?: number }
    }>
  }>
}

Fields

kind

The type of entity the event is for.

• "group" Contains "group"'s, "item"'s, or "check"'s, passes or fails based on children.
• "item" Contains "check"'s, passes or fails based on children.
• "check" Represents an individual assertion that either passes or fails.

You can have any of these (including "check"'s) with top-level "id"'s, you don't have to wrap everything in a "group" or "item".

Note that if a "group" or "item" fails, they should always have at least one child kind that failed. i.e. You should always have at least one reported "check" that failed.

Kind Examples

The structure of reported event kinds may differ a lot based on the tool,

Testing Framework

- item: Test
  - check: Assertion
- group: Suite
  - item: Test
    - check: Assertion
    - check: Assertion
  - item: Test
    - check: Assertion
  - group: Nested Suite
    - item: Test
      - check: Assertion
      - check: Assertion
      - check: Assertion

Linter

- group: File 1
  - check: Lint Error
  - check: Lint Error
- group: File 2
  - check: Lint Error
  - check: Lint Error

Type Checker

- check: Type Error
- check: Type Error
- check: Type Error
- check: Type Error
- check: Type Error
- check: Type Error

event

The name of the event.

• "started" Execution has started.
• "info" Still executing, but has some information.
• "completed" Execution has completed.

You don't need to send a "started" event in order to send a "completed" event. You only really need to send it when there is a gap in time between when something began running and when it completed. For example, a simple check does not need to report when it started running.

status

• "running"
• "passed"
• "failed"
• "errored"
• "skipped"

All statuses except for "running" should be considered final. They should only be updated by restarting an entity.

# Bad
- 0: started (running)
- 0: info (failed)
- 0: completed (passed)

# Good
- 0: started (running)
- 0: completed (failed)
- 0: started (running) "Retry"
- 0: completed (passed)

# Bad
- 0: started (running)
  - 0.0: started (running)
  - 0.0: completed (passed)
  - 0.1: started (running)
  - 0.1: completed (failed)
- 0: completed (failed)
  - 0.1: started (running)
  - 0.1: completed (passed) "Retry"
- 0: completed (passed)

# Good
- 0: started (running)
  - 0.0: started (running)
  - 0.0: completed (passed)
  - 0.1: started (running)
  - 0.1: completed (failed)
- 0: completed (failed)
- 0: started (running) "Retry"
  - 0.1: started (running)
  - 0.1: completed (passed) "Retry"
- 0: completed (passed)

A parent's status should be "passed" when all children "passed":

- 0: passed
  - 0.0: passed
  - 0.1: passed

A parent may have a status of "passed" or "failed" when a child was "skipped". Skips may have multiple different reasons. They are not all failures depending on the situation.

- 0: passed
  - 0.0: passed
  - 0.1: skipped
- 1: failed
  - 1.0: passed
  - 1.1: skipped

But when one or more children fail or error, you must fail the parent.

- 0: failed
  - 0.0: failed
  - 0.1: passed
- 2: failed
  - 2.0: errored
  - 2.1: passed
- 1: failed
  - 1.0: failed
  - 1.1: errored

Inversely, if you may not fail a parent if all the children passed, express your failure with another "check". Although it can error.

# Bad
- 0: failed
  - 0.0: passed
  - 0.1: passed

# Good
- 0: failed
  - 0.0: passed
  - 0.1: passed
  - 0.2: errored "An error occurred when cleaning up the database"

# Good
- 0: errored "An error occurred when cleaning up the database"
  - 0.0: passed
  - 0.1: passed

A parent can also choose to update their status to "failed" early when a child has failed and there are more children still running.

- 0: failed
  - 0.0: failed
  - 0.1: running
  - 0.2: running

id

The identifier for the entity.

A string which a series of numbers separated by periods . (i.e. 2.3.1.12)

{ "kind": "group", ... "id": "0", ... }
{ "kind": "item", ... "id": "0.0", ... }
{ "kind": "check", ... "id": "0.0.0", ... }
{ "kind": "check", ... "id": "0.0.1", ... }
{ "kind": "item", ... "id": "0.0", ... }
{ "kind": "item", ... "id": "0.1", ... }
{ "kind": "check", ... "id": "0.1.0", ... }
{ "kind": "item", ... "id": "0.1", ... }
{ "kind": "item", ... "id": "0.2", ... }
{ "kind": "check", ... "id": "0.2.0", ... }
{ "kind": "check", ... "id": "0.2.1", ... }
{ "kind": "item", ... "id": "0.2", ... }
...

This is a flat way to describe a tree of groups, items, and checks.

- group: "0"
  - item: "0.0"
    - check: "0.0.0"
    - check: "0.0.1"
  - item: "0.1"
    - check: "0.1.0"
  - item: "0.2"
    - check: "0.2.0"
    - check: "0.2.1"
- group: "1"
  - item: "1.0"
    - check: "1.0.0"
- group: "2"
  - item: "2.0"
    - check: "2.0.0"
    - check: "2.0.1"

You can determine the "parent" of the entity by stripping the last .number (i.e. s/\.\d+$//)

time

The offset time the event occured.

A number in milliseconds with arbitrary precision up to nanoseconds.

{ ... "time": 257.0332779996097  ... }
{ ... "time": 304.6154760001227  ... }
{ ... "time": 397.152665999718   ... }
{ ... "time": 425.59379499964416 ... }
{ ... "time": 496.1821520002559  ... }

To calculate the duration of an entity you can compare the entity's "start" and "completed" events.

{ "id": "0.0", "event": "started", "time": 304.6154760001227 ... }
{ "id": "0.0", "event": "completed", "time": 425.59379499964416 ... }

425.5937949996ms - 304.6154760001227ms = 120.9783189995ms = 0.12s

Important! You should not assume that event times from entities with different "id"'s have anything to do with one another. They could have been run in separate parallel processes, or even across different machines.

{ "id": "1.8", "event": "started", "time": 304.6154760001227 ... } // from process 1
{ "id": "4.3", "event": "started", "time": 4235.59379499964416 ... } // from process 2
{ "id": "2.2", "event": "started", "time": 204.152665999718 ... } // from process 3
// none of these times have anything to do with one another

content

The content of the event.

An array of messages and (optionally) source locations.

{ ...
  "content": [
    { "message": "number", "source": [{ "file": "/path/to/source/file.js", "start": { "line": 15, "column": 12 }, "end": { "line": 15, "column": 19 } }] },
    { "message": "is not compatible with" },
    { "message": "string", "source": [{ "file": "/path/to/source/file.js", "start": { "line": 19, "column": 8 }, "end": { "line": 19, "column": 14 } }] }
  ]
  ...
}

Every element in the "content" array should be an object with the following shape:

interface ContentPart {
  message: string,
  source?: Array<{
    file: string,
    start?: { line: number, column?: number },
    end?: { line: number, column?: number }
  }>
}

Content Targets

When interpreting elements of "content" you should not attempt to "fill in" the missing elements.

• If there is no "source", do not make one up or try associating it with the other elements in the "content" array.
• If there is a "file" but no "start" or "end" positions, assume it means the file itself, not the range of the file's content.
• If there is a "line" but no "column", assume it means the entire line, not range of the line's content.
• If there is a "start" but no "end", assume it means that exact position, not a range of a single characters, or to the rest of the file.

Content Positions

When interpreting a position:

• "line" is 1-index based
• "column" is 0-index based

This means that when you are interpreting a "column" it is the index before a character. It targets this "in between" position and not the character itself.

For example if we have the following line:

012345

And we are selecting columns 1 through 4, we would get the following selection:

0[123]45
  ^^^

Content Examples

A message with no location:

{ ...
  "content": [{
    "message": "No tests found"
  }]
}

No tests found

An entire file:

{ ...
  "content": [{
    "message": "File named incorectly",
    "source": [{
      "file": "/path/to/file.js"
    }]
  }]
}

/path/to/file.js: File named incorrectly

A specific line in a file:

{ ...
  "content": [{
    "message": "File too long",
    "source": [{
      "file": "/path/to/file.js",
      "start": { "line": 10000 }
    }]
  }]
}

/path/to/file.js
   9998 |   "lorem",
   9999 |   "ipsum",
> 10000 |   "dolor",
  10001 |   "sit"
  10002 |   "amet",
File too long

A specific position in a file:

{ ...
  "content": [{
    "message": "Missing closing brace",
    "source": [{
      "file": "/path/to/file.js",
      "start": { "line": 24, "column": 4 }
    }]
  }]
}

/path/to/file.js
  22 |     for (let item of items) {
  23 |       total += item.price;
> 24 |
     |     ^ Missing closing brace
  25 |     return toPriceString(total);
  26 |   }

A range of lines in a file:

{ ...
  "content": [{
    "message": "...",
    "source": [{
      "file": "/path/to/file.js",
      "start": { "line": 12 },
      "end": { "line": 14 }
    }]
  }]
}

/path/to/file.js
  11 |   ...
> 12 |     ...
> 13 |     ...
> 14 |     ...
  15 |   ...
...

A range in a file:

{ ...
  "content": [{
    "message": "Variable name `public` is reserved word",
    "source": [{
      "file": "/path/to/file.js",
      "start": { "line": 9, "column": 6 },
      "end": { "line": 9, "column": 13 }
    }]
  }]
}

/path/to/file.js
   7 |
   8 |   function isPublic(item) {
>  9 |     let public = item.public;
     |         ^^^^^^ Variable name `public` is reserved word
  10 |     let childrenPublic = item.children.every(child => {
  11 |       return isPublic(child);

Multiple ranges in a file:

{ ...
  "content": [{
    "message": "Binding `active` declared multiple times",
    "source": [{
      "file": "/path/to/file.js",
      "start": { "line": 9, "column": 6 },
      "end": { "line": 9, "column": 13 }
    }, {
      "file": "/path/to/file.js",
      "start": { "line": 27, "column": 6 },
      "end": { "line": 27, "column": 13 }
    }]
  }]
}

/path/to/file.js
   8 |   function isActive(item) {
>  9 |     let active = item.active;
     |         ^^^^^^
  10 |     let childrenActive = item.children.every(child => {
    ...
  26 |
  27 |     let active = item.children.filter(child => {
     |         ^^^^^^
  28 |       return isActive(child);
Binding `active` declared multiple times

Multi-part message

{ ...
  "content": [
    {
      "message": "number",
      "source": [{
        "file": "/path/to/one.js",
        "start": { "line": 15, "column": 38 },
        "end": { "line": 15, "column": 45 }
      }]
    },
    {
      "message": "is not compatible with"
    },
    {
      "message": "string",
      "source": [{
        "file": "/path/to/two.js",
        "start": { "line": 9, "column": 6 },
        "end": { "line": 9, "column": 13 }
      }]
    }
  }]
}

/path/to/one.js
  14 |
> 15 | export function calculateTotal(item): number {
     |                                       ^^^^^^ number
  16 |

is not compatible with

/path/to/two.js
  36 |     let message = 'Total: ';
> 37 |     let total: string = calculateTotal(item);
     |                ^^^^^^ string
  38 |     message += total;