test(create-gatsby): add test for handling errors in install plugins

packages/create-gatsby/src/__tests__/install-plugins.ts

@@ -0,0 +1,61 @@
+import { installPlugins } from "../install-plugins"
+import { reporter } from "../reporter"
+import { requireResolve } from "../require-utils"
+
+jest.mock(`../require-utils`)
+jest.mock(`../reporter`)
+
+jest.mock(
+  `somewhere-virtually-existing`,
+  () => {
+    // Make sure not to resolve `addPlugins` in order to safely handle error
+    return {}
+  },
+  { virtual: true }
+)
+
+describe(`install-plugins`, () => {
+  afterEach(() => {
+    jest.resetAllMocks()
+  })
+
+  it(`reports an error explaining that gatsby is not installed`, async () => {
+    ;(requireResolve as any).mockImplementation(() => undefined)
+
+    await installPlugins([], {}, `not-existing-path`, [])
+
+    // Test function behaviour but improves the DX, it probably worth it
+    expect(reporter.error).toBeCalledWith(
+      `Could not find "gatsby" in not-existing-path. Perhaps it wasn't installed properly?`
+    )
+  })
+
+  it(`reports an error when the gatsby cli is not installed`, async () => {
+    ;(requireResolve as any).mockImplementation(path => {
+      if (path === `gatsby-cli/lib/handlers/plugin-add`) {
+        throw new Error()
+      }
+      return `somewhere-i-belong`
+    })
+
+    await installPlugins([], {}, `not-existing-path`, [])
+
+    // Test function behaviour but improves the DX, it probably worth it
+    expect(reporter.error).toBeCalledWith(
+      `gatsby-cli not installed, or is too old`
+    )
+  })
+
+  it(`reports an error when add plugins fails somehow`, async () => {
+    ;(requireResolve as any).mockImplementation(
+      () => `somewhere-virtually-existing`
+    )
+
+    await installPlugins([], {}, `not-existing-path`, [])
+
+    // Test function behaviour but improves the DX, it probably worth it
+    expect(reporter.error).toBeCalledWith(
+      `Something went wrong when trying to add the plugins to the project: addPlugins is not a function`
+    )
+  })
+})

packages/create-gatsby/src/install-plugins.ts

@@ -1,49 +1,81 @@
 import { reporter } from "./reporter"
 import path from "path"
 import { PluginConfigMap } from "."
-export async function installPlugins(
-  plugins: Array<string>,
-  pluginOptions: PluginConfigMap = {},
-  rootPath: string,
-  packages: Array<string>
-): Promise<void> {
-  let installPluginCommand
-  let gatsbyPath
+import { requireResolve } from "./require-utils"
 
+const resolveGatsbyPath = (rootPath: string): string | never => {
   try {
-    gatsbyPath = require.resolve(`gatsby/package.json`, {
+    const gatsbyPath = requireResolve(`gatsby/package.json`, {
       paths: [rootPath],
     })
-  } catch (e) {
-    // Not found
-    console.warn(e)
-  }
 
-  if (!gatsbyPath) {
-    reporter.error(
+    if (!gatsbyPath) throw new Error()
+
+    return gatsbyPath
+  } catch (e) {
+    throw new Error(
       `Could not find "gatsby" in ${rootPath}. Perhaps it wasn't installed properly?`
     )
-    return
   }
+}
 
+const resolveGatsbyCliPath = (
+  rootPath: string,
+  gatsbyPath: string
+): string | never => {
   try {
-    installPluginCommand = require.resolve(
+    const installPluginCommand = requireResolve(
       `gatsby-cli/lib/handlers/plugin-add`,
       {
         // Try to find gatsby-cli in the site root, or in the site's gatsby dir
         paths: [rootPath, path.dirname(gatsbyPath)],
       }
     )
+
+    if (!installPluginCommand) throw new Error()
+
+    return installPluginCommand
   } catch (e) {
-    // The file is missing
+    throw new Error(`gatsby-cli not installed, or is too old`)
   }
+}
 
-  if (!installPluginCommand) {
-    reporter.error(`gatsby-cli not installed, or is too old`)
-    return
+const addPluginsToProject = async (
+  installPluginCommand: string,
+  plugins: Array<string>,
+  pluginOptions: PluginConfigMap = {},
+  rootPath: string,
+  packages: Array<string>
+): Promise<void> => {
+  try {
+    const { addPlugins } = require(installPluginCommand)
+    await addPlugins(plugins, pluginOptions, rootPath, packages)
+  } catch (e) {
+    throw new Error(
+      `Something went wrong when trying to add the plugins to the project: ${e.message}`
+    )
   }
+}
 
-  const { addPlugins } = require(installPluginCommand)
+export async function installPlugins(
+  plugins: Array<string>,
+  pluginOptions: PluginConfigMap = {},
+  rootPath: string,
+  packages: Array<string>
+): Promise<void> {
+  try {
+    const gatsbyPath = resolveGatsbyPath(rootPath)
+    const installPluginCommand = resolveGatsbyCliPath(rootPath, gatsbyPath)
 
-  await addPlugins(plugins, pluginOptions, rootPath, packages)
+    await addPluginsToProject(
+      installPluginCommand,
+      plugins,
+      pluginOptions,
+      rootPath,
+      packages
+    )
+  } catch (e) {
+    reporter.error(e.message)
+    return
+  }
 }

packages/create-gatsby/src/require-utils.ts

@@ -0,0 +1,4 @@
+export const requireResolve = (
+  id: string,
+  options?: { paths?: Array<string> | undefined } | undefined
+): string => require.resolve(id, options)