Assert

A GitHub Action for asserting actual is expected in GitHub Workflows, designed for GitHub Action integration tests and robust build pipelines.

• Cast action input values from strings to type for type safety
• Distribute reusable assertions via npm
• Write local Javascript assertions to meet project-specific testing needs
• Run tests against multiple values using each

jobs:
  test-actor:
    runs-on: ubuntu-latest
    steps:
      - name: Test actor is @shrink
        uses: prompt/actions-assert@v4
        with:
          assertion: npm://@assertions/is-equal:v1
          actual: "${{ github.actor }}"
          expected: shrink

Jump to complete examples ↓

Outputs

Name	Description	Example
message	Human readable result of the assertion	Value is equal to expected "Hello, World!"
passed	Boolean describing whether the assertion passed	true
failed	Boolean describing whether the assertion failed	false

Inputs

Name	Description	Default	Examples
assertion	Reference to a supported assertion in source://name format		npm://@assertions/is-equal:v1 local://is-even
expected	Value the assertion is looking for		Hello, World!
actual	Value the assertion will test against the expected value		${{steps.fields.outputs.greeting}}
error-message	Error message to output when assertion fails		Commit does not include a distributable build
type	A supported data type that actual and expected will be cast to before performing assertion	string	string json number
each	Parse multi-line actual into many values and perform assertion against each	false	true false
local-path	Path to directory containing local assertion	${{github.workspace}}	.github/workflows/assertions
error-on-fail	Report error in step when assertion fails	true	false
convert-empty-to-null[1]	Convert empty input values to null	true	false

[1] convert-empty-to-null is a workaround for a GitHub Actions Runner bug #924

Data Types

Name	Description
string	A Javascript String⇗
number	A Javascript Number⇗
json	JavaScript value or object from JSON.parse()⇗

Each

When each is enabled, the Action splits actual by new-line into multiple values and asserts against each value. The final result is an aggregate of each result: all individual assertions must pass for the aggregate to pass.

Assertions

An assertion is a Javascript function that accepts expected and actual parameters and then returns a Result. A Result has a boolean pass parameter and a message string.

module.exports = function (expected, actual) {
  return {
    pass: actual === expected,
    message: `compared ${actual} to ${expected}`
  }
}

Sources

The test builder resolves assertion references using source and name accepted in source://name format.

Source	Resolved To	Example
npm	An npm⇗ package with an assertion as the main exported module⇗	npm://@assertions/is-equal:v1
local	A Javascript file (on the runner's filesystem) that exports an assertion as default	local://is-equal

npm

Version Pinning

📌 An npm assertion reference should include a valid npm package version. Unlike npm itself, an npm assertion reference without a version will default to v1 instead of latest.

ℹ️ assertion: npm://@assertions/is-equal
✅ assertion: npm://@assertions/is-equal:1
✅ assertion: npm://@assertions/is-equal:v1
✅ assertion: npm://@assertions/is-equal:v1.0.0
✅ assertion: npm://@assertions/is-equal:latest

@assertions

A collection of first-party assertions is available on npm within the @assertions^⇗ organisation.

Package	Test
@assertions/is-equal	actual is equal in value to expected
@assertions/is-strictly-equal	actual is equal in value and type to expected
@assertions/starts-with	actual starts with expected
@assertions/directory-exists	path expected exists and is a directory

Third-party assertions are discoverable via 🔎 actions-assert on npm.

Distributing Assertions

Add 🔖 actions-assert to package.json keywords^⇗ for an assertion to be discoverable via npm search^⇗.

Examples

SemVer Aliases Are Prefixed

prompt/actions-semver-aliases generates aliases for a Semantic Version with an optional prefix, in this example, the job tests that the optional prefix is applied to each alias.

on: push

jobs:
  test-aliases-are-prefixed:
    runs-on: ubuntu-latest
    steps:
      - name: Generate SemVer aliases with prefix
        id: prefixed
        uses: prompt/actions-semver-aliases@v1
        with:
          version: "3.14.1"
          prefix: "v"
          major: true
          minor: false
      - name: Assert alias is prefixed
        uses: prompt/actions-assert@v4
        with:
          assertion: npm://@assertions/starts-with:v1
          each: true
          actual: "${{ steps.prefixed.outputs.list }}"
          expected: "v"
          error-message: "SemVer Alias is not prefixed with v"

A complete test Workflow for prompt/actions-semver-aliases using multiple assertions is available in .github/workflows/test.yml.

Delete Invalid Tags

A repository may restrict tags to commits that include a specific file; in this example, the job deletes a newly created tag if the distributable directory (dist) does not exist.

on:
  push:
    tags:
      - "**"

jobs:
  validate-tag:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v2
      - uses: prompt/actions-assert@v4
        with:
          assertion: npm://@assertions/directory-exists:v1
          expected: dist
          error-message: "A commit without a dist is not allowed to be tagged"
      - if: failure()
        name: Delete tag
        uses: prompt/actions-delete-tag@v1

Automatic Release Packaging

A Workflow packages the Action automatically when a collaborator created a new tag. Any reference to this Action in a Workflow must use a tag (mutable) or the commit hash of a tag (immutable).

✅ uses: prompt/actions-assert@v2
✅ uses: prompt/actions-assert@v2.0.0
✅ uses: prompt/actions-assert@0d888b7601af756fff1ffc9d0d0dca8fcc214f0a
❌ uses: prompt/actions-assert@main

The blog post Package GitHub Actions automatically with GitHub Actions describes how this achieved.