chore(gatsby): migrate merge-gatsby-config to TypeScript

gatsbyjs · May 12, 2020 · eb09da2 · eb09da2
1 parent 885e3e4
commit eb09da2
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Showing 4 changed files with 48 additions and 33 deletions.
diff --git a/packages/gatsby/src/bootstrap/load-themes/index.js b/packages/gatsby/src/bootstrap/load-themes/index.js
@@ -1,6 +1,6 @@
 const { createRequireFromPath } = require(`gatsby-core-utils`)
 const path = require(`path`)
-const mergeGatsbyConfig = require(`../../utils/merge-gatsby-config`)
+const { mergeGatsbyConfig } = require(`../../utils/merge-gatsby-config`)
 const Promise = require(`bluebird`)
 const _ = require(`lodash`)
 const debug = require(`debug`)(`gatsby:load-themes`)

diff --git a/packages/gatsby/src/redux/types.ts b/packages/gatsby/src/redux/types.ts
@@ -57,6 +57,7 @@ export interface IGatsbyConfig {
   developMiddleware?: any
   proxy?: any
   pathPrefix?: string
+  mapping?: Record<string, string>
 }
 
 export interface IGatsbyNode {

diff --git a/...rc/utils/__tests__/merge-gatsby-config.js → ...rc/utils/__tests__/merge-gatsby-config.ts b/...rc/utils/__tests__/merge-gatsby-config.js → ...rc/utils/__tests__/merge-gatsby-config.ts
@@ -1,4 +1,4 @@
-const mergeGatsbyConfig = require(`../merge-gatsby-config`)
+import { mergeGatsbyConfig } from "../merge-gatsby-config"
 
 describe(`Merge gatsby config`, () => {
   it(`Merging empty config is an identity operation`, () => {

diff --git a/...s/gatsby/src/utils/merge-gatsby-config.js → ...s/gatsby/src/utils/merge-gatsby-config.ts b/...s/gatsby/src/utils/merge-gatsby-config.js → ...s/gatsby/src/utils/merge-gatsby-config.ts
@@ -1,30 +1,16 @@
-const _ = require(`lodash`)
-/**
- * Defines how a theme object is merged with the user's config
- */
-module.exports = (a, b) => {
-  // a and b are gatsby configs, If they have keys, that means there are values to merge
-  const allGatsbyConfigKeysWithAValue = _.uniq(
-    Object.keys(a).concat(Object.keys(b))
-  )
+import _ from "lodash"
+import { IGatsbyConfig } from "../redux/types"
 
-  // reduce the array of mergable keys into a single gatsby config object
-  const mergedConfig = allGatsbyConfigKeysWithAValue.reduce(
-    (config, gatsbyConfigKey) => {
-      // choose a merge function for the config key if there's one defined,
-      // otherwise use the default value merge function
-      const mergeFn = howToMerge[gatsbyConfigKey] || howToMerge.byDefault
-      return {
-        ...config,
-        [gatsbyConfigKey]: mergeFn(a[gatsbyConfigKey], b[gatsbyConfigKey]),
-      }
-    },
-    {}
-  )
-
-  // return the fully merged config
-  return mergedConfig
-}
+type ConfigKey = keyof IGatsbyConfig
+type Metadata = IGatsbyConfig["siteMetadata"]
+type Plugins = IGatsbyConfig["plugins"]
+type PluginEntry =
+  | string
+  | {
+      resolve: string
+      options: Record<string, unknown>
+    }
+type Mapping = IGatsbyConfig["mapping"]
 
 /**
  * Normalize plugin spec before comparing so
@@ -33,7 +19,7 @@ module.exports = (a, b) => {
  *  - { resolve: `gatsby-plugin-name`, options: {} }
  * are all considered equal
  */
-const normalizePluginEntry = entry =>
+const normalizePluginEntry = (entry: PluginEntry): PluginEntry =>
   _.isString(entry)
     ? { resolve: entry, options: {} }
     : _.isObject(entry)
@@ -46,15 +32,43 @@ const howToMerge = {
    * This makes sure that if a single value is defined, that one it used.
    * We prefer the "right" value, because the user's config will be "on the right"
    */
-  byDefault: (a, b) => b || a,
-  siteMetadata: (objA, objB) => _.merge({}, objA, objB),
+  byDefault: (a: ConfigKey, b: ConfigKey): ConfigKey => b || a,
+  siteMetadata: (objA: Metadata, objB: Metadata): Metadata =>
+    _.merge({}, objA, objB),
   // plugins are concatenated and uniq'd, so we don't get two of the same plugin value
-  plugins: (a = [], b = []) =>
+  plugins: (a: Plugins = [], b: Plugins = []): Plugins =>
     _.uniqWith(a.concat(b), (a, b) =>
       _.isEqual(
         _.pick(normalizePluginEntry(a), [`resolve`, `options`]),
         _.pick(normalizePluginEntry(b), [`resolve`, `options`])
       )
     ),
-  mapping: (objA, objB) => _.merge({}, objA, objB),
+  mapping: (objA: Mapping, objB: Mapping): Mapping => _.merge({}, objA, objB),
+}
+
+/**
+ * Defines how a theme object is merged with the user's config
+ */
+export const mergeGatsbyConfig = (a, b): IGatsbyConfig => {
+  // a and b are gatsby configs, If they have keys, that means there are values to merge
+  const allGatsbyConfigKeysWithAValue = _.uniq(
+    Object.keys(a).concat(Object.keys(b))
+  )
+
+  // reduce the array of mergable keys into a single gatsby config object
+  const mergedConfig = allGatsbyConfigKeysWithAValue.reduce(
+    (config, gatsbyConfigKey) => {
+      // choose a merge function for the config key if there's one defined,
+      // otherwise use the default value merge function
+      const mergeFn = howToMerge[gatsbyConfigKey] || howToMerge.byDefault
+      return {
+        ...config,
+        [gatsbyConfigKey]: mergeFn(a[gatsbyConfigKey], b[gatsbyConfigKey]),
+      }
+    },
+    {}
+  )
+
+  // return the fully merged config
+  return mergedConfig
 }