refactor(generator): ensure proper deep merge of array values in api.extendPackage

Also fixes #970 by injecting eslint config when invoking ts plugin in an existing project
with eslint plugin installed.

packages/@vue/cli-plugin-typescript/generator/index.js

@@ -73,6 +73,18 @@ module.exports = (api, {
     })
   }
 
+  const hasESLint = api.hasPlugin('eslint')
+  if (hasESLint) {
+    api.extendPackage({
+      devDependencies: {
+        '@vue/eslint-config-typescript': '^3.0.0-rc.5'
+      },
+      eslintConfig: {
+        extends: ['@vue/typescript']
+      }
+    })
+  }
+
   api.render('./template', {
     isTest: process.env.VUE_CLI_TEST || process.env.VUE_CLI_DEBUG,
     hasMocha,

packages/@vue/cli/__tests__/invoke.spec.js

@@ -76,7 +76,7 @@ test('invoke with prompts', async () => {
   await assertUpdates(project)
 })
 
-test('invoke with existing files', async () => {
+test('invoke with ts', async () => {
   const project = await create(`invoke-existing`, {
     useConfigFiles: true,
     plugins: {
@@ -86,7 +86,7 @@ test('invoke with existing files', async () => {
   })
   // mock install
   const pkg = JSON.parse(await project.read('package.json'))
-  pkg.devDependencies['@vue/cli-plugin-eslint'] = '*'
+  pkg.devDependencies['@vue/cli-plugin-typescript'] = '*'
   await project.write('package.json', JSON.stringify(pkg, null, 2))
 
   // mock existing vue.config.js
@@ -97,11 +97,12 @@ test('invoke with existing files', async () => {
     extends: ['plugin:vue/essential', 'eslint:recommended']
   }))
 
-  await project.run(`${require.resolve('../bin/vue')} invoke eslint --config airbnb --lintOn commit`)
+  await project.run(`${require.resolve('../bin/vue')} invoke typescript --classComponent --useTsWithBabel`)
 
-  await assertUpdates(project)
-  const updatedVueConfig = await project.read('vue.config.js')
-  expect(updatedVueConfig).toMatch(`module.exports = { lintOnSave: false }`)
+  const updatedESLintrc = parseJS(await project.read('.eslintrc.js'))
+  expect(updatedESLintrc).toEqual(Object.assign({}, baseESLintConfig, {
+    extends: ['plugin:vue/essential', 'eslint:recommended', '@vue/typescript']
+  }))
 })
 
 test('invoke with existing files (yaml)', async () => {
@@ -109,13 +110,9 @@ test('invoke with existing files (yaml)', async () => {
     useConfigFiles: true,
     plugins: {
       '@vue/cli-plugin-babel': {},
-      '@vue/cli-plugin-eslint': { config: 'base' }
+      '@vue/cli-plugin-eslint': {}
     }
   })
-  // mock install
-  const pkg = JSON.parse(await project.read('package.json'))
-  pkg.devDependencies['@vue/cli-plugin-eslint'] = '*'
-  await project.write('package.json', JSON.stringify(pkg, null, 2))
 
   const eslintrc = parseJS(await project.read('.eslintrc.js'))
   expect(eslintrc).toEqual(Object.assign({}, baseESLintConfig, {
@@ -137,6 +134,7 @@ extends:
 extends:
   - 'plugin:vue/essential'
   - 'eslint:recommended'
+  - '@vue/airbnb'
 `.trim())
 })
 

packages/@vue/cli/lib/GeneratorAPI.js

@@ -14,6 +14,7 @@ const ConfigTransform = require('./ConfigTransform')
 const isString = val => typeof val === 'string'
 const isFunction = val => typeof val === 'function'
 const isObject = val => val && typeof val === 'object'
+const mergeArrayWithDedupe = (a, b) => Array.from(new Set([...a, ...b]))
 
 class GeneratorAPI {
   /**
@@ -140,9 +141,9 @@ class GeneratorAPI {
       } else if (!(key in pkg)) {
         pkg[key] = value
       } else if (Array.isArray(value) && Array.isArray(existing)) {
-        pkg[key] = existing.concat(value)
+        pkg[key] = mergeArrayWithDedupe(existing, value)
       } else if (isObject(value) && isObject(existing)) {
-        pkg[key] = merge(existing, value)
+        pkg[key] = merge(existing, value, { arrayMerge: mergeArrayWithDedupe })
       } else {
         pkg[key] = value
       }

packages/@vue/cli/lib/util/configTransforms.js

@@ -3,6 +3,11 @@ const stringifyJS = require('./stringifyJS')
 const { loadModule } = require('@vue/cli-shared-utils')
 const merge = require('deepmerge')
 
+const mergeArrayWithDedupe = (a, b) => Array.from(new Set([...a, ...b]))
+const mergeOptions = {
+  arrayMerge: mergeArrayWithDedupe
+}
+
 const isObject = val => val && typeof val === 'object'
 
 const transformJS = {
@@ -20,10 +25,10 @@ const transformJS = {
       Object.keys(value).forEach(key => {
         const originalValue = existing[key]
         const newValue = value[key]
-        if (Array.isArray(newValue)) {
-          changedData[key] = newValue
+        if (Array.isArray(originalValue) && Array.isArray(newValue)) {
+          changedData[key] = mergeArrayWithDedupe(originalValue, newValue)
         } else if (isObject(originalValue) && isObject(newValue)) {
-          changedData[key] = merge(originalValue, newValue)
+          changedData[key] = merge(originalValue, newValue, mergeOptions)
         } else {
           changedData[key] = newValue
         }
@@ -37,12 +42,18 @@ const transformJS = {
 
 const transformJSON = {
   read: ({ source }) => JSON.parse(source),
-  write: ({ value, existing }) => JSON.stringify(merge(existing, value), null, 2)
+  write: ({ value, existing }) => {
+    return JSON.stringify(merge(existing, value, mergeOptions), null, 2)
+  }
 }
 
 const transformYAML = {
   read: ({ source }) => require('js-yaml').safeLoad(source),
-  write: ({ value, existing }) => require('js-yaml').safeDump(merge(existing, value))
+  write: ({ value, existing }) => {
+    return require('js-yaml').safeDump(merge(existing, value, mergeOptions), {
+      skipInvalid: true
+    })
+  }
 }
 
 const transformLines = {