fix(gatsby): correctly pick up browserslist overrides (#9669)

* fix: start ironing out browserslist issues

* chore: make linter happy

* chore: change to expected shape

* refactor: move browserslist functionality into gatsby core

packages/babel-preset-gatsby/src/__tests__/index.js

@@ -101,8 +101,9 @@ it(`Specifies proper presets and plugins for build-html stage`, () => {
 })
 
 it(`Allows to configure browser targets`, () => {
+  const targets = `last 1 version`
   const { presets } = preset(null, {
-    targets: { browsers: [`last 1 version`] },
+    targets,
   })
 
   expect(presets[0]).toEqual([
@@ -111,9 +112,7 @@ it(`Allows to configure browser targets`, () => {
       loose: true,
       modules: false,
       useBuiltIns: `usage`,
-      targets: {
-        browsers: [`last 1 version`],
-      },
+      targets,
     },
   ])
 })

packages/babel-preset-gatsby/src/index.js

@@ -1,6 +1,6 @@
 const path = require(`path`)
 
-const r = m => require.resolve(m)
+const resolve = m => require.resolve(m)
 
 const loadCachedConfig = () => {
   let pluginBabelConfig = {}
@@ -13,7 +13,7 @@ const loadCachedConfig = () => {
   return pluginBabelConfig
 }
 
-function preset(context, options = {}) {
+module.exports = function preset(_, options = {}) {
   let { targets = null } = options
 
   const pluginBabelConfig = loadCachedConfig()
@@ -25,16 +25,14 @@ function preset(context, options = {}) {
         node: `current`,
       }
     } else {
-      targets = {
-        browsers: pluginBabelConfig.browserslist,
-      }
+      targets = pluginBabelConfig.browserslist
     }
   }
 
   return {
     presets: [
       [
-        r(`@babel/preset-env`),
+        resolve(`@babel/preset-env`),
         {
           loose: true,
           modules: stage === `test` ? `commonjs` : false,
@@ -43,7 +41,7 @@ function preset(context, options = {}) {
         },
       ],
       [
-        r(`@babel/preset-react`),
+        resolve(`@babel/preset-react`),
         {
           useBuiltIns: true,
           pragma: `React.createElement`,
@@ -53,15 +51,15 @@ function preset(context, options = {}) {
     ],
     plugins: [
       [
-        r(`@babel/plugin-proposal-class-properties`),
+        resolve(`@babel/plugin-proposal-class-properties`),
         {
           loose: true,
         },
       ],
-      r(`babel-plugin-macros`),
-      r(`@babel/plugin-syntax-dynamic-import`),
+      resolve(`babel-plugin-macros`),
+      resolve(`@babel/plugin-syntax-dynamic-import`),
       [
-        r(`@babel/plugin-transform-runtime`),
+        resolve(`@babel/plugin-transform-runtime`),
         {
           helpers: true,
           regenerator: true,
@@ -70,5 +68,3 @@ function preset(context, options = {}) {
     ],
   }
 }
-
-module.exports = preset

packages/gatsby/src/bootstrap/index.js

@@ -12,6 +12,7 @@ const Promise = require(`bluebird`)
 
 const apiRunnerNode = require(`../utils/api-runner-node`)
 const mergeGatsbyConfig = require(`../utils/merge-gatsby-config`)
+const getBrowserslist = require(`../utils/browserslist`)
 const { graphql } = require(`graphql`)
 const { store, emitter } = require(`../redux`)
 const loadPlugins = require(`./load-plugins`)
@@ -56,10 +57,13 @@ module.exports = async (args: BootstrapArgs) => {
   // and invokes Gatsby API based on actions.
   require(`../redux/plugin-runner`)
 
+  const directory = slash(args.directory)
+
   const program = {
     ...args,
+    browserslist: getBrowserslist(directory),
     // Fix program directory path for windows env.
-    directory: slash(args.directory),
+    directory,
   }
 
   store.dispatch({

packages/gatsby/src/commands/build.js

@@ -17,7 +17,6 @@ function reportFailure(msg, err: Error) {
 type BuildArgs = {
   directory: string,
   sitePackageJson: object,
-  browserslist: string[],
   prefixPaths: boolean,
   noUglify: boolean,
   openTracingConfigFile: string,

packages/gatsby/src/internal-plugins/load-babel-config/gatsby-node.js

@@ -21,8 +21,15 @@ exports.onPreBootstrap = async ({ store }) => {
   await apiRunnerNode(`onCreateBabelConfig`, {
     stage: `build-html`,
   })
-  const babelrcState = store.getState().babelrc
-  babelrcState.browserslist = browserslist
-  const babelState = JSON.stringify(babelrcState.stages, null, 4)
+
+  const babelState = JSON.stringify(
+    {
+      ...store.getState().babelrc,
+      browserslist,
+    },
+    null,
+    2
+  )
+
   await fs.writeFile(directoryPath(`.cache/babelState.json`), babelState)
 }

packages/gatsby/src/utils/__tests__/browserslist.js

@@ -0,0 +1,31 @@
+jest.mock(`browserslist/node`, () => {
+  return {
+    findConfig: jest.fn(),
+  }
+})
+const path = require(`path`)
+const getBrowsersList = require(`../browserslist`)
+const { findConfig: mockedFindConfig } = require(`browserslist/node`)
+
+const BASE = path.resolve(`.`)
+
+describe(`browserslist`, () => {
+  it(`prefers returned browserslist results`, () => {
+    const defaults = [`IE 11`]
+    mockedFindConfig.mockReturnValueOnce({
+      defaults,
+    })
+
+    const list = getBrowsersList(BASE)
+
+    expect(list).toEqual(defaults)
+  })
+
+  it(`falls back to defaults`, () => {
+    mockedFindConfig.mockReturnValueOnce(undefined)
+
+    const list = getBrowsersList(BASE)
+
+    expect(list).toEqual([`>0.25%`, `not dead`])
+  })
+})

packages/gatsby/src/utils/babel-loader-helpers.js

@@ -2,7 +2,11 @@ const path = require(`path`)
 const _ = require(`lodash`)
 
 const loadCachedConfig = () => {
-  let pluginBabelConfig = { test: { plugins: [], presets: [] } }
+  let pluginBabelConfig = {
+    stages: {
+      test: { plugins: [], presets: [] },
+    },
+  }
   if (process.env.NODE_ENV !== `test`) {
     pluginBabelConfig = require(path.join(
       process.cwd(),
@@ -15,7 +19,7 @@ const loadCachedConfig = () => {
 const getCustomOptions = () => {
   const pluginBabelConfig = loadCachedConfig()
   const stage = process.env.GATSBY_BUILD_STAGE || `test`
-  return pluginBabelConfig[stage].options
+  return pluginBabelConfig.stages[stage].options
 }
 
 const prepareOptions = (babel, resolve = require.resolve) => {
@@ -59,14 +63,14 @@ const prepareOptions = (babel, resolve = require.resolve) => {
   // Go through babel state and create config items for presets/plugins from.
   const reduxPlugins = []
   const reduxPresets = []
-  pluginBabelConfig[stage].plugins.forEach(plugin => {
+  pluginBabelConfig.stages[stage].plugins.forEach(plugin => {
     reduxPlugins.push(
       babel.createConfigItem([resolve(plugin.name), plugin.options], {
         type: `plugin`,
       })
     )
   })
-  pluginBabelConfig[stage].presets.forEach(preset => {
+  pluginBabelConfig.stages[stage].presets.forEach(preset => {
     reduxPresets.push(
       babel.createConfigItem([resolve(preset.name), preset.options], {
         type: `preset`,

packages/gatsby/src/utils/browserslist.js

@@ -0,0 +1,31 @@
+const path = require(`path`)
+const browserslist = require(`browserslist/node`)
+
+function installedGatsbyVersion(directory) {
+  try {
+    const { version } = require(path.join(
+      directory,
+      `node_modules`,
+      `gatsby`,
+      `package.json`
+    ))
+    return parseInt(version.split(`.`)[0], 10)
+  } catch (e) {
+    return undefined
+  }
+}
+
+module.exports = function getBrowsersList(directory) {
+  const fallback =
+    installedGatsbyVersion(directory) === 1
+      ? [`>1%`, `last 2 versions`, `IE >= 9`]
+      : [`>0.25%`, `not dead`]
+
+  const config = browserslist.findConfig(directory)
+
+  if (config && config.defaults) {
+    return config.defaults
+  }
+
+  return fallback
+}