test: Add test case for the creation of redirects for SSR and DSG pages.

src/__tests__/gatsby-node.js

@@ -1,46 +1,117 @@
-import { testPluginOptionsSchema } from "gatsby-plugin-utils"
+jest.mock('../plugin-data', () => {
+  return {
+    __esModule: true,
+    default: jest.fn().mockReturnValue({
+      publicFolder: jest.fn().mockReturnValue('mock-file-path'),
+    }),
+  }
+})
+jest.mock('../build-headers-program', () => {
+  return {
+    __esModule: true,
+    default: jest.fn(),
+  }
+})
+jest.mock('fs-extra', () => {
+  return {
+    __esModule: true,
+    default: jest.fn(),
+    existsSync: jest.fn(),
+    readFile: jest.fn(),
+    writeFile: jest.fn(),
+  }
+})
 
-import { pluginOptionsSchema } from "../gatsby-node"
+// Importing writeFile here gives us access to the mocked method to assert the correct content is written to the file within test cases
+import { writeFile } from 'fs-extra'
+import { testPluginOptionsSchema } from 'gatsby-plugin-utils'
+import { pluginOptionsSchema, onPostBuild } from '../gatsby-node'
 
 describe(`gatsby-node.js`, () => {
-  it(`should provide meaningful errors when fields are invalid`, async () => {
-    const expectedErrors = [
-      `"headers" must be of type object`,
-      `"allPageHeaders" must be an array`,
-      `"mergeSecurityHeaders" must be a boolean`,
-      `"mergeLinkHeaders" must be a boolean`,
-      `"mergeCachingHeaders" must be a boolean`,
-      `"transformHeaders" must have an arity lesser or equal to 2`,
-      `"generateMatchPathRewrites" must be a boolean`,
-    ]
-
-    const { errors } = await testPluginOptionsSchema(pluginOptionsSchema, {
-      headers: `this should be an object`,
-      allPageHeaders: `this should be an array`,
-      mergeSecurityHeaders: `this should be a boolean`,
-      mergeLinkHeaders: `this should be a boolean`,
-      mergeCachingHeaders: `this should be a boolean`,
-      transformHeaders: (too, many, args) => ``,
-      generateMatchPathRewrites: `this should be a boolean`,
+  describe('testPluginOptionsSchema', () => {
+    it(`should provide meaningful errors when fields are invalid`, async () => {
+      const expectedErrors = [
+        `"headers" must be of type object`,
+        `"allPageHeaders" must be an array`,
+        `"mergeSecurityHeaders" must be a boolean`,
+        `"mergeLinkHeaders" must be a boolean`,
+        `"mergeCachingHeaders" must be a boolean`,
+        `"transformHeaders" must have an arity lesser or equal to 2`,
+        `"generateMatchPathRewrites" must be a boolean`,
+      ]
+
+      const { errors } = await testPluginOptionsSchema(pluginOptionsSchema, {
+        headers: `this should be an object`,
+        allPageHeaders: `this should be an array`,
+        mergeSecurityHeaders: `this should be a boolean`,
+        mergeLinkHeaders: `this should be a boolean`,
+        mergeCachingHeaders: `this should be a boolean`,
+        transformHeaders: (too, many, args) => ``,
+        generateMatchPathRewrites: `this should be a boolean`,
+      })
+
+      expect(errors).toEqual(expectedErrors)
     })
 
-    expect(errors).toEqual(expectedErrors)
+    it(`should validate the schema`, async () => {
+      const { isValid } = await testPluginOptionsSchema(pluginOptionsSchema, {
+        headers: {
+          '/some-page': [`Bearer: Some-Magic-Token`],
+          '/some-other-page': [`some`, `great`, `headers`],
+        },
+        allPageHeaders: [`First header`, `Second header`],
+        mergeSecurityHeaders: true,
+        mergeLinkHeaders: false,
+        mergeCachingHeaders: true,
+        transformHeaders: () => null,
+        generateMatchPathRewrites: false,
+      })
+
+      expect(isValid).toBe(true)
+    })
   })
 
-  it(`should validate the schema`, async () => {
-    const { isValid } = await testPluginOptionsSchema(pluginOptionsSchema, {
-      headers: {
-        "/some-page": [`Bearer: Some-Magic-Token`],
-        "/some-other-page": [`some`, `great`, `headers`],
-      },
-      allPageHeaders: [`First header`, `Second header`],
-      mergeSecurityHeaders: true,
-      mergeLinkHeaders: false,
-      mergeCachingHeaders: true,
-      transformHeaders: () => null,
-      generateMatchPathRewrites: false,
+  describe('onPostBuild', () => {
+    let store = {}
+    const reporter = {
+      info: jest.fn(),
+    }
+    beforeEach(() => {
+      store = {
+        getState: jest.fn().mockReturnValue({
+          redirects: [],
+          pages: [
+            {
+              mode: 'SSR',
+              path: 'some/path',
+            },
+            {
+              mode: 'DSG',
+              path: 'some/other/path',
+            },
+          ],
+          functions: [],
+          program: { directory: '' },
+        }),
+      }
+    })
+
+    afterEach(() => {
+      jest.resetAllMocks()
     })
 
-    expect(isValid).toBe(true)
+    it('creates redirects for SSR and DSG pages in format Netlify expects', async () => {
+      const expectedValue = [
+        '',
+        '## Created with gatsby-plugin-netlify',
+        'some/path  /.netlify/functions/__ssr  200',
+        '/page-data/some/path/page-data.json  /.netlify/functions/__ssr  200',
+        'some/other/path  /.netlify/functions/__dsg  200',
+        '/page-data/some/other/path/page-data.json  /.netlify/functions/__dsg  200',
+      ].join(`\n`)
+
+      await onPostBuild({ store, pathPrefix: '', reporter }, {})
+      expect(writeFile).toHaveBeenCalledWith('mock-file-path', expectedValue)
+    })
   })
 })