feat(GeneratorAPI): allow passing options to api.extendPackage

packages/@vue/cli-plugin-babel/migrator/index.js

@@ -1,14 +1,20 @@
 const { chalk } = require('@vue/cli-shared-utils')
 
-module.exports = (api) => {
-  api.transformScript('babel.config.js', require('../codemods/usePluginPreset'))
+module.exports = api => {
+  api.transformScript(
+    'babel.config.js',
+    require('../codemods/usePluginPreset')
+  )
 
   if (api.fromVersion('^3')) {
-    api.extendPackage({
-      dependencies: {
-        'core-js': '^3.6.4'
-      }
-    }, true)
+    api.extendPackage(
+      {
+        dependencies: {
+          'core-js': '^3.6.4'
+        }
+      },
+      { warnIncompatibleVersions: false }
+    )
 
     // TODO: implement a codemod to migrate polyfills
     api.exitLog(`core-js has been upgraded from v2 to v3.

packages/@vue/cli-plugin-eslint/migrator/index.js

@@ -54,7 +54,7 @@ module.exports = async (api) => {
       Object.assign(newDeps, getDeps(api, 'prettier'))
     }
 
-    api.extendPackage({ devDependencies: newDeps }, true)
+    api.extendPackage({ devDependencies: newDeps }, { warnIncompatibleVersions: false })
 
     // in case anyone's upgrading from the legacy `typescript-eslint-parser`
     if (api.hasPlugin('typescript')) {

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

@@ -1,7 +1,10 @@
-module.exports = (api) => {
-  api.extendPackage({
-    devDependencies: {
-      typescript: require('../package.json').devDependencies.typescript
-    }
-  }, true)
+module.exports = api => {
+  api.extendPackage(
+    {
+      devDependencies: {
+        typescript: require('../package.json').devDependencies.typescript
+      }
+    },
+    { warnIncompatibleVersions: false }
+  )
 }

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

@@ -73,6 +73,10 @@ fs.ensureDirSync(path.resolve(templateDir, '_vscode'))
 fs.writeFileSync(path.resolve(templateDir, '_vscode/config.json'), `{}`)
 fs.writeFileSync(path.resolve(templateDir, '_gitignore'), 'foo')
 
+beforeEach(() => {
+  logs.warn = []
+})
+
 test('api: extendPackage', async () => {
   const generator = new Generator('/', {
     pkg: {
@@ -376,6 +380,130 @@ test('api: extendPackage merge warn nonstrictly semver deps', async () => {
   })).toBe(true)
 })
 
+test('api: extendPackage + { merge: false }', async () => {
+  const generator = new Generator('/', {
+    pkg: {
+      name: 'hello',
+      list: [1],
+      vue: {
+        foo: 1,
+        bar: 2
+      }
+    },
+    plugins: [{
+      id: 'test',
+      apply: api => {
+        api.extendPackage(
+          {
+            name: 'hello2',
+            list: [2],
+            vue: {
+              foo: 2,
+              baz: 3
+            }
+          },
+          { merge: false }
+        )
+      }
+    }]
+  })
+
+  await generator.generate()
+
+  const pkg = JSON.parse(fs.readFileSync('/package.json', 'utf-8'))
+  expect(pkg).toEqual({
+    name: 'hello2',
+    list: [2],
+    vue: {
+      foo: 2,
+      baz: 3
+    }
+  })
+})
+
+test('api: extendPackage + { prune: true }', async () => {
+  const generator = new Generator('/', {
+    pkg: {
+      name: 'hello',
+      version: '0.0.0',
+      dependencies: {
+        foo: '1.0.0'
+      },
+      vue: {
+        bar: 1,
+        baz: 2
+      }
+    },
+    plugins: [{
+      id: 'test',
+      apply: api => {
+        api.extendPackage(
+          {
+            name: null,
+            dependencies: {
+              foo: null,
+              qux: '2.0.0'
+            },
+            vue: {
+              bar: null,
+              baz: 3
+            }
+          },
+          { prune: true }
+        )
+      }
+    }]
+  })
+
+  await generator.generate()
+
+  const pkg = JSON.parse(fs.readFileSync('/package.json', 'utf-8'))
+  expect(pkg).toEqual({
+    version: '0.0.0',
+    dependencies: {
+      qux: '2.0.0'
+    },
+    vue: {
+      baz: 3
+    }
+  })
+})
+
+test('api: extendPackage + { warnIncompatibleVersions: false }', async () => {
+  const generator = new Generator('/', {
+    pkg: {
+      devDependencies: {
+        eslint: '^4.0.0'
+      }
+    },
+    plugins: [{
+      id: 'test',
+      apply: api => {
+        api.extendPackage(
+          {
+            devDependencies: {
+              eslint: '^6.0.0'
+            }
+          },
+          { warnIncompatibleVersions: false }
+        )
+      }
+    }]
+  })
+
+  await generator.generate()
+  const pkg = JSON.parse(fs.readFileSync('/package.json', 'utf-8'))
+
+  // should not warn about the version conflicts
+  expect(logs.warn.length).toBe(0)
+  // should use the newer version
+  expect(pkg).toEqual({
+    devDependencies: {
+      eslint: '^6.0.0'
+    }
+  })
+})
+
 test('api: render fs directory', async () => {
   const generator = new Generator('/', { plugins: [
     {

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

@@ -1,7 +1,7 @@
 const fs = require('fs')
 const ejs = require('ejs')
 const path = require('path')
-const merge = require('deepmerge')
+const deepmerge = require('deepmerge')
 const resolve = require('resolve')
 const { isBinaryFileSync } = require('isbinaryfile')
 const mergeDeps = require('./util/mergeDeps')
@@ -14,6 +14,23 @@ 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]))
+function pruneObject (obj) {
+  if (typeof obj === 'object') {
+    for (const k in obj) {
+      if (!obj.hasOwnProperty(k)) {
+        continue
+      }
+
+      if (obj[k] == null) {
+        delete obj[k]
+      } else {
+        obj[k] = pruneObject(obj[k])
+      }
+    }
+  }
+
+  return obj
+}
 
 class GeneratorAPI {
   /**
@@ -176,15 +193,34 @@ class GeneratorAPI {
 
   /**
    * Extend the package.json of the project.
-   * Nested fields are deep-merged unless `{ merge: false }` is passed.
    * Also resolves dependency conflicts between plugins.
    * Tool configuration fields may be extracted into standalone files before
    * files are written to disk.
    *
    * @param {object | () => object} fields - Fields to merge.
-   * @param {boolean} forceNewVersion - Ignore version conflicts when updating dependency version
+   * @param {object} [options] - Options for extending / merging fields.
+   * @param {boolean} [options.prune=false] - Remove null or undefined fields
+   *    from the object after merging.
+   * @param {boolean} [options.merge=true] deep-merge nested fields, note
+   *    that dependency fields are always deep merged regardless of this option.
+   * @param {boolean} [options.warnIncompatibleVersions=true] Output warning
+   *    if two dependency version ranges don't intersect.
    */
-  extendPackage (fields, forceNewVersion) {
+  extendPackage (fields, options = {}) {
+    const extendOptions = {
+      prune: false,
+      merge: true,
+      warnIncompatibleVersions: true
+    }
+
+    // this condition statement is added for compatiblity reason, because
+    // in version 4.0.0 to 4.1.2, there's no `options` object, but a `forceNewVersion` flag
+    if (typeof options === 'boolean') {
+      extendOptions.warnIncompatibleVersions = !options
+    } else {
+      Object.assign(extendOptions, options)
+    }
+
     const pkg = this.generator.pkg
     const toMerge = isFunction(fields) ? fields(pkg) : fields
     for (const key in toMerge) {
@@ -197,18 +233,22 @@ class GeneratorAPI {
           existing || {},
           value,
           this.generator.depSources,
-          forceNewVersion
+          extendOptions
         )
-      } else if (!(key in pkg)) {
+      } else if (!extendOptions.merge || !(key in pkg)) {
         pkg[key] = value
       } else if (Array.isArray(value) && Array.isArray(existing)) {
         pkg[key] = mergeArrayWithDedupe(existing, value)
       } else if (isObject(value) && isObject(existing)) {
-        pkg[key] = merge(existing, value, { arrayMerge: mergeArrayWithDedupe })
+        pkg[key] = deepmerge(existing, value, { arrayMerge: mergeArrayWithDedupe })
       } else {
         pkg[key] = value
       }
     }
+
+    if (extendOptions.prune) {
+      pruneObject(pkg)
+    }
   }
 
   /**