feat: overwrite arrays in setData (#652)

breaking change

Author: eddyerburgh

docs/api/wrapper/setData.md

@@ -1,6 +1,8 @@
 ## setData(data)
 
-Sets `Wrapper` `vm` data and forces update.
+Sets `Wrapper` `vm` data.
+
+setData works by merging existing properties, except for arrays which are overwritten.
 
 **Note the Wrapper must contain a Vue instance.**
 

flow/modules.flow.js

@@ -12,7 +12,7 @@ declare module 'lodash/cloneDeep' {
   declare module.exports: any;
 }
 
-declare module 'lodash/merge' {
+declare module 'lodash/mergeWith' {
   declare module.exports: any;
 }
 

packages/test-utils/src/wrapper.js

@@ -1,7 +1,7 @@
 // @flow
 
 import Vue from 'vue'
-import merge from 'lodash/merge'
+import mergeWith from 'lodash/mergeWith'
 import getSelectorTypeOrThrow from './get-selector-type'
 import {
   REF_SELECTOR,
@@ -424,7 +424,9 @@ export default class Wrapper implements BaseWrapper {
       if (typeof data[key] === 'object' && data[key] !== null &&
 						!Array.isArray(data[key])) {
         // $FlowIgnore : Problem with possibly null this.vm
-        const newObj = merge(this.vm[key], data[key])
+        const newObj = mergeWith(this.vm[key], data[key], (objValue, srcValue) => {
+          return Array.isArray(srcValue) ? srcValue : undefined
+        })
         // $FlowIgnore : Problem with possibly null this.vm
         this.vm.$set(this.vm, [key], newObj)
       } else {

test/specs/wrapper/setData.spec.js

@@ -165,7 +165,8 @@ describeWithShallowAndMount('setData', (mountingMethod) => {
           },
           propB: 'b'
         }
-      })
+      }),
+      render: () => {}
     }
     const wrapper = mountingMethod(TestComponent)
     wrapper.setData({
@@ -179,16 +180,31 @@ describeWithShallowAndMount('setData', (mountingMethod) => {
     expect(wrapper.vm.anObject.propA.prop2).to.equal('b')
   })
 
-  it('sets array data properly', () => {
+  it('does not merge arrays', () => {
     const TestComponent = {
+      template: '<div>{{nested.nested.nestedArray[0]}}</div>',
       data: () => ({
-        items: [1, 2]
+        items: [1, 2],
+        nested: {
+          nested: {
+            nestedArray: [1, 2]
+          }
+        }
       })
     }
     const wrapper = mountingMethod(TestComponent)
     wrapper.setData({
       items: [3]
     })
     expect(wrapper.vm.items).to.deep.equal([3])
+    wrapper.setData({
+      nested: {
+        nested: {
+          nestedArray: [10]
+        }
+      }
+    })
+    expect(wrapper.text()).to.equal('10')
+    expect(wrapper.vm.nested.nested.nestedArray).to.deep.equal([10])
   })
 })