add test and move to async/await

Author: Slashgear

Diff for: packages/@vuepress/core/lib/node/Page.js

@@ -282,14 +282,14 @@ module.exports = class Page {
    * @api private
    */
 
-  enhance (enhancers) {
-    return enhancers.reduce(async (accumulator, { pluginName, value }) => {
-      return accumulator
-        .then(() => value(this))
-        .catch(error => {
-          console.log(error)
-          throw new Error(`[${pluginName}] execute extendPageData failed.`)
-        })
-    }, Promise.resolve())
+  async enhance (enhancers) {
+    for (const { name: pluginName, value: enhancer } of enhancers) {
+      try {
+        await enhancer(this)
+      } catch (error) {
+        console.log(error)
+        throw new Error(`[${pluginName}] execute extendPageData failed.`)
+      }
+    }
   }
 }

Diff for: packages/@vuepress/core/lib/node/__tests__/prepare/Page.spec.js

@@ -102,5 +102,54 @@ describe('Page', () => {
     expect(page._content.startsWith('---')).toBe(true)
     expect(page._strippedContent.startsWith('---')).toBe(false)
   })
+
+  describe('enhance - ', () => {
+    let page
+    let enhancers
+
+    beforeEach(() => {
+      page = new Page({ path: '/' }, app)
+      enhancers = [
+        {
+          pluginName: 'foo',
+          value: jest.fn()
+        },
+        {
+          pluginName: 'foo',
+          value: jest.fn()
+        }
+      ]
+      global.console.log = jest.fn()
+    })
+
+    test('should loop over sync enhancers', async () => {
+      await page.enhance(enhancers)
+
+      return enhancers.map(enhancer => expect(enhancer.value).toBeCalled())
+    })
+
+    test('should loop over sync and async enhancers', async () => {
+      const mixedEnhancers = [...enhancers, {
+        pluginName: 'blog',
+        value: jest.fn().mockResolvedValue({})
+      }]
+      await page.enhance(mixedEnhancers)
+
+      return mixedEnhancers.map(enhancer => expect(enhancer.value).toBeCalled())
+    })
+
+    test('should log when enhancing when failing', async () => {
+      const error = { errorMessage: 'this is an error message' }
+      expect.assertions(1)
+      try {
+        await page.enhance([{
+          pluginName: 'error-plugin',
+          value: jest.fn().mockRejectedValue(error)
+        }])
+      } catch (e) {
+        expect(console.log).toBeCalledWith(error)
+      }
+    })
+  })
 })