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Validating YAML Starter Configuration Tests in GatsbyJS

This test suite validates the YAML configuration for Gatsby starters, ensuring proper structure and content validation for the starter template registry. It implements comprehensive validation rules for required fields, data types, and uniqueness constraints.

Test Coverage Overview

The test suite provides extensive coverage for YAML validation in Gatsby starters:

Validates required fields (url, repo, description, tags, features)
Checks field type constraints and formats
Ensures unique URLs and repository references
Validates against GitHub-specific repository patterns

Implementation Analysis

The implementation uses Jest’s mocking capabilities to simulate file system interactions and validate YAML content. It employs beforeEach hooks for test setup and mock resets, while utilizing expect assertions to verify validation outcomes.

The testing pattern follows AAA (Arrange-Act-Assert) with clear separation of setup, execution, and verification phases.

Technical Details

Jest test framework with mock functions
Custom danger module implementation
YAML validation utilities
Mock response handling for file content simulation
Dynamic test data generation

Best Practices Demonstrated

The test suite exemplifies several testing best practices:

Isolated test cases with proper setup/teardown
Comprehensive error message validation
Mock cleanup between tests
Explicit test case descriptions
Structured validation scenarios

gatsbyjs/gatsby

peril/tests/validate-yaml/validate-yaml-starters.test.ts

            
jest.mock("danger", () => jest.fn())
import * as danger from "danger"
import { validateYaml, utils } from "../../rules/validate-yaml"
const dm = danger as any
const mockedUtils = utils as any

let mockedResponses: { [id: string]: any }
const setStartersYmlContent = (content: string) => {
  mockedResponses["docs/starters.yml"] = content
}
const setCategoriesContent = (content: string) => {
  mockedResponses["docs/categories.yml"] = content
}
const resetMockedResponses = () => {
  mockedResponses = {}
}

dm.warn = jest.fn()
mockedUtils.addErrorMsg = jest.fn()

beforeEach(() => {
  resetMockedResponses()
  setCategoriesContent(`
starter:
  - CMS:Headless,
  - Styling:CSS-in-JS
  - Official
site:
  - Web Development
  - WordPress
`)
  dm.warn.mockClear()
  mockedUtils.addErrorMsg.mockClear()
  dm.danger = {
    git: {
      modified_files: ["docs/starters.yml"],
    },
    github: {
      pr: {
        head: {
          repo: {
            full_name: "test/test",
          },
          ref: "branch",
        },
      },
      utils: {
        fileContents: (path: string) => mockedResponses[path],
      },
    },
  }
})

describe("a new PR", () => {
  it(`Valid entry passes validation`, async () => {
    setStartersYmlContent(`
    - url: https://gatsbyjs.github.io/gatsby-starter-default/
      repo: https://github.com/gatsbyjs/gatsby-starter-default
      description: official default
      features:
        - It works
      tags:
        - Official
    `)

    await validateYaml()
    expect(dm.warn).not.toBeCalled()
    expect(mockedUtils.addErrorMsg).not.toBeCalled()
  })

  it(`Check for required fields and disallow unknown fields`, async () => {
    setStartersYmlContent(`
      - test: loem
    `)

    await validateYaml()
    expect(dm.warn).toBeCalled()
    expect(mockedUtils.addErrorMsg).toHaveBeenCalledTimes(6)
    expect(mockedUtils.addErrorMsg).toHaveBeenCalledWith(
      0,
      expect.stringContaining('"url" is required'),
      expect.anything()
    )
    expect(mockedUtils.addErrorMsg).toHaveBeenCalledWith(
      0,
      expect.stringContaining('"repo" is required'),
      expect.anything()
    )
    expect(mockedUtils.addErrorMsg).toHaveBeenCalledWith(
      0,
      expect.stringContaining('"description" is required'),
      expect.anything()
    )
    expect(mockedUtils.addErrorMsg).toHaveBeenCalledWith(
      0,
      expect.stringContaining('"tags" is required'),
      expect.anything()
    )
    expect(mockedUtils.addErrorMsg).toHaveBeenCalledWith(
      0,
      expect.stringContaining('"features" is required'),
      expect.anything()
    )
    expect(mockedUtils.addErrorMsg).toHaveBeenCalledWith(
      0,
      expect.stringContaining('"test" is not allowed'),
      expect.anything()
    )
  })

  it(`Check type of fields`, async () => {
    setStartersYmlContent(`
    - url: 1
      repo: 2
      description: 3
      tags: 4
      features: 5
    - url: www.google.com
      repo: www.google.com
      description: lorem
      tags:
        - 1
        - true
      features:
        - 2
        - false
    - url: www.google.com
      repo: https://gitlab.com/gatsbyjs/gatsby-starter-default
      description: lorem
      features:
        - It works
      tags:
        - I'm a fancy new tag
        - I don't play by the rules
    `)

    await validateYaml()
    expect(dm.warn).toBeCalled()
    expect(mockedUtils.addErrorMsg).toHaveBeenCalledWith(
      0,
      expect.stringContaining('"url" must be a string'),
      expect.anything()
    )
    expect(mockedUtils.addErrorMsg).toHaveBeenCalledWith(
      0,
      expect.stringContaining('"repo" must be a string'),
      expect.anything()
    )
    expect(mockedUtils.addErrorMsg).toHaveBeenCalledWith(
      0,
      expect.stringContaining('"description" must be a string'),
      expect.anything()
    )
    expect(mockedUtils.addErrorMsg).toHaveBeenCalledWith(
      0,
      expect.stringContaining('"tags" must be an array'),
      expect.anything()
    )
    expect(mockedUtils.addErrorMsg).toHaveBeenCalledWith(
      0,
      expect.stringContaining('"features" must be an array'),
      expect.anything()
    )
    expect(mockedUtils.addErrorMsg).toHaveBeenCalledWith(
      1,
      expect.stringContaining(
        '"url" must be a valid uri with a scheme matching the https|http pattern'
      ),
      expect.anything()
    )
    expect(mockedUtils.addErrorMsg).toHaveBeenCalledWith(
      1,
      expect.stringContaining(
        '"repo" must be a valid uri with a scheme matching the https|http pattern'
      ),
      expect.anything()
    )
    expect(mockedUtils.addErrorMsg).toHaveBeenCalledWith(
      1,
      expect.stringContaining('"0" must be a string'),
      expect.anything()
    )
    expect(mockedUtils.addErrorMsg).toHaveBeenCalledWith(
      1,
      expect.stringContaining('"1" must be a string'),
      expect.anything()
    )

    expect(mockedUtils.addErrorMsg).toHaveBeenCalledWith(
      2,
      expect.stringContaining(
        `"0" must be one of [CMS:Headless,, Styling:CSS-in-JS, Official]`
      ),
      expect.anything()
    )
  })

  it(`Doesn't allow non GitHub repos`, async () => {
    setStartersYmlContent(`
    - url: https://gatsbyjs.github.io/gatsby-starter-default/
      repo: https://gitlab.com/gatsbyjs/gatsby-starter-default
      description: official default
      features:
        - It works
      tags:
        - Official
    `)

    await validateYaml()
    expect(dm.warn).toBeCalled()
    expect(mockedUtils.addErrorMsg).toHaveBeenCalledTimes(1)
    expect(mockedUtils.addErrorMsg).toHaveBeenCalledWith(
      0,
      expect.stringContaining(
        '"repo" with value "https://gitlab.com/gatsbyjs/gatsby-starter-default" fails to match the required pattern'
      ),
      expect.anything()
    )
  })

  it(`Check for duplicates`, async () => {
    setStartersYmlContent(`
    - url: https://gatsbyjs.github.io/gatsby-starter-default/
      repo: https://github.com/gatsbyjs/gatsby-starter-default
      description: official default
      features:
        - It works
      tags:
        - Official
    - url: https://gatsbyjs.github.io/gatsby-starter-default2/
      repo: https://github.com/gatsbyjs/gatsby-starter-default
      description: official default
      features:
        - It works
      tags:
        - Official
    - url: https://gatsbyjs.github.io/gatsby-starter-default/
      repo: https://github.com/gatsbyjs/gatsby-starter-default2
      description: official default
      features:
        - It works
      tags:
        - Official
    `)

    await validateYaml()
    expect(dm.warn).toBeCalled()
    expect(mockedUtils.addErrorMsg).toHaveBeenCalledTimes(2)
    expect(mockedUtils.addErrorMsg).toHaveBeenCalledWith(
      1,
      expect.stringContaining('"repo" is not unique'),
      expect.anything()
    )
    expect(mockedUtils.addErrorMsg).toHaveBeenCalledWith(
      2,
      expect.stringContaining('"url" is not unique'),
      expect.anything()
    )
  })
})