introduce jest with basic unit tests

.eslintrc.js

@@ -7,7 +7,7 @@ module.exports = {
     ecmaVersion: '2017'
   },
   extends: ['standard', 'prettier'],
-  plugins: ['node'],
+  plugins: ['node', 'jest'],
   rules: {
     'node/no-unsupported-features/es-syntax': 2
   }

gatsby-node.test.js

@@ -0,0 +1,160 @@
+const nock = require('nock')
+const fs = require('fs-extra')
+
+const { createResolvers } = require('./gatsby-node')
+
+const registeredResolvers = new Map()
+const actualCacheMap = new Map()
+const cacheDir = __dirname + '/.cache'
+fs.ensureDirSync(cacheDir)
+const cache = {
+  get: jest.fn((key) => actualCacheMap.get(key)),
+  set: jest.fn((key, value) => actualCacheMap.set(key, value)),
+  directory: cacheDir,
+  actualMap: actualCacheMap
+}
+const createResolversMock = jest.fn((resolvers) => {
+  Object.keys(resolvers).forEach((resolverName) => {
+    registeredResolvers.set(resolverName, resolvers[resolverName])
+  })
+})
+const store = {
+  getState: jest.fn(() => {
+    return { program: { directory: process.cwd() }, status: {} }
+  })
+}
+const reporter = { info: jest.fn(), panic: jest.fn() }
+
+const contentfulAssetFixture = {
+  file: {
+    url: '//images.contentful.com/mocked.svg',
+    contentType: 'image/svg+xml'
+  }
+}
+
+describe('general', () => {
+  beforeEach(() => {
+    createResolversMock.mockClear()
+    registeredResolvers.clear()
+    reporter.panic.mockClear()
+  })
+
+  test('create resolver', async () => {
+    createResolvers({
+      cache,
+      createResolvers: createResolversMock,
+      store,
+      reporter
+    })
+    expect(registeredResolvers.size).toBe(1)
+    expect(registeredResolvers.has('ContentfulAsset')).toBe(true)
+
+    const resolverData = registeredResolvers.get('ContentfulAsset')
+    expect(resolverData.svg).toBeTruthy()
+    expect(resolverData.svg.type).toBe('InlineSvg')
+  })
+})
+
+describe('gatsby-source-contentful', () => {
+  beforeEach(() => {
+    createResolversMock.mockClear()
+    registeredResolvers.clear()
+    reporter.panic.mockClear()
+    nock.cleanAll()
+    cache.actualMap.clear()
+  })
+  test('process Contentful Asset', async () => {
+    createResolvers({
+      cache,
+      createResolvers: createResolversMock,
+      store,
+      reporter
+    })
+
+    const scope = nock('http://images.contentful.com')
+      .get(`/mocked.svg`)
+      .replyWithFile(200, __dirname + '/fixtures/gatsby-monogram.svg', {
+        'Content-Type': 'image/svg+xml'
+      })
+
+    const resolverData = registeredResolvers.get('ContentfulAsset')
+    const result = await resolverData.svg.resolve(contentfulAssetFixture)
+
+    expect(reporter.panic).not.toBeCalled()
+    expect(scope.isDone()).toBeTruthy()
+
+    expect(result.absolutePath).toContain('svg')
+    expect(result.absolutePath).toContain(__dirname)
+    expect(result.content).toBe(
+      `<svg xmlns=\"http://www.w3.org/2000/svg\" viewBox=\"0 0 28 28\"><circle cx=\"14\" cy=\"14\" r=\"14\" fill=\"#639\"/><path fill=\"#fff\" d=\"M6.2 21.8C4.1 19.7 3 16.9 3 14.2L13.9 25c-2.8-.1-5.6-1.1-7.7-3.2zm10.2 2.9L3.3 11.6C4.4 6.7 8.8 3 14 3c3.7 0 6.9 1.8 8.9 4.5l-1.5 1.3A9.23 9.23 0 0014 5a9.1 9.1 0 00-8.5 6L17 22.5c2.9-1 5.1-3.5 5.8-6.5H18v-2h7c0 5.2-3.7 9.6-8.6 10.7z\"/></svg>`
+    )
+    expect(result.dataURI).toBe(
+      `data:image/svg+xml,%3csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 28 28'%3e%3ccircle cx='14' cy='14' r='14' fill='%23639'/%3e%3cpath fill='white' d='M6.2 21.8C4.1 19.7 3 16.9 3 14.2L13.9 25c-2.8-.1-5.6-1.1-7.7-3.2zm10.2 2.9L3.3 11.6C4.4 6.7 8.8 3 14 3c3.7 0 6.9 1.8 8.9 4.5l-1.5 1.3A9.23 9.23 0 0014 5a9.1 9.1 0 00-8.5 6L17 22.5c2.9-1 5.1-3.5 5.8-6.5H18v-2h7c0 5.2-3.7 9.6-8.6 10.7z'/%3e%3c/svg%3e`
+    )
+    expect(result.originalContent).toBe(
+      fs.readFileSync(__dirname + '/fixtures/gatsby-monogram.svg').toString()
+    )
+    expect(result.relativePath).toContain('mocked.svg')
+  })
+  test('removes pixelated data from Contentful Asset', async () => {
+    createResolvers({
+      cache,
+      createResolvers: createResolversMock,
+      store,
+      reporter
+    })
+
+    const scope = nock('http://images.contentful.com')
+      .get(`/mocked-pixelated.svg`)
+      .replyWithFile(
+        200,
+        __dirname + '/fixtures/gatsby-logo-with-pixel-data.svg',
+        {
+          'Content-Type': 'image/svg+xml'
+        }
+      )
+
+    const resolverData = registeredResolvers.get('ContentfulAsset')
+    const pixelatedFixture = JSON.parse(JSON.stringify(contentfulAssetFixture))
+    pixelatedFixture.file.url = `//images.contentful.com/mocked-pixelated.svg`
+
+    const result = await resolverData.svg.resolve(pixelatedFixture)
+
+    expect(reporter.panic).not.toBeCalled()
+    expect(scope.isDone()).toBeTruthy()
+    expect(result.content).not.toContain('data:image/png')
+  })
+  test('skip non-svg Contentful assets', async () => {
+    createResolvers({
+      cache,
+      createResolvers: createResolversMock,
+      store,
+      reporter
+    })
+    const resolverData = registeredResolvers.get('ContentfulAsset')
+
+    const noSvgFixture = JSON.parse(JSON.stringify(contentfulAssetFixture))
+    noSvgFixture.file.contentType = 'no/svg'
+    const result = await resolverData.svg.resolve(noSvgFixture)
+
+    expect(result).toBe(null)
+    expect(reporter.panic).not.toHaveBeenCalled()
+  })
+
+  test('skip empty Contentful assets', async () => {
+    createResolvers({
+      cache,
+      createResolvers: createResolversMock,
+      store,
+      reporter
+    })
+    const resolverData = registeredResolvers.get('ContentfulAsset')
+
+    const noFileFixture = JSON.parse(JSON.stringify(contentfulAssetFixture))
+    delete noFileFixture.file.url
+    const result = await resolverData.svg.resolve(noFileFixture)
+
+    expect(result).toBe(null)
+    expect(reporter.panic).not.toHaveBeenCalled()
+  })
+})

package.json

@@ -8,7 +8,8 @@
   },
   "scripts": {
     "format": "prettier --write {src/**/*.js,*.{js,json}}",
-    "lint": "eslint index.js"
+    "lint": "eslint index.js",
+    "test": "jest gatsby-node.test.js"
   },
   "files": [
     "index.js",
@@ -56,16 +57,20 @@
     "svgo": "^1.3.2"
   },
   "devDependencies": {
+    "@types/jest": "^27.4.0",
     "eslint": "^6.8.0",
     "eslint-config-prettier": "^6.10.0",
     "eslint-config-standard": "^14.1.0",
     "eslint-plugin-import": "^2.20.1",
+    "eslint-plugin-jest": "^26.0.0",
     "eslint-plugin-node": "^11.0.0",
     "eslint-plugin-promise": "^4.2.1",
     "eslint-plugin-standard": "^4.0.1",
     "gatsby": "^2.19.11",
     "husky": "^4.2.1",
+    "jest": "^27.4.7",
     "lint-staged": "^10.0.7",
+    "nock": "^13.2.2",
     "prettier": "^1.19.1"
   },
   "peerDependencies": {