feat: async filters, closes #232

src/template/filter/filter.ts

@@ -20,6 +20,6 @@ export class Filter {
       if (isKeyValuePair(arg)) argv.push([arg[0], yield evalToken(arg[1], context)])
       else argv.push(yield evalToken(arg, context))
     }
-    return this.impl.apply({ context }, [value, ...argv])
+    return yield this.impl.apply({ context }, [value, ...argv])
   }
 }

test/e2e/parse-and-render.ts

@@ -45,13 +45,13 @@ describe('.parseAndRender()', function () {
     const result2 = await engine.render(template, ctx)
     expect(result2).to.equal('1,2')
   })
-  it('should render filters', async function () {
+  it('should support the "join" filter', async function () {
     var ctx = { names: ['alice', 'bob'] }
     var template = engine.parse('<p>{{names | join: ","}}</p>')
     const html = await engine.render(template, ctx)
     return expect(html).to.equal('<p>alice,bob</p>')
   })
-  it('should render accessive filters', async function () {
+  it('should support the "first" filter', async function () {
     var src = '{% assign my_array = "apples, oranges, peaches, plums" | split: ", " %}' +
       '{{ my_array | first }}'
     const html = await engine.parseAndRender(src)

test/integration/liquid/register-filters.ts

@@ -4,21 +4,33 @@ import { Liquid } from '../../../src/liquid'
 describe('liquid#registerFilter()', function () {
   const liquid = new Liquid()
 
-  describe('object arguments', function () {
+  describe('key-value arguments', function () {
     liquid.registerFilter('obj_test', function (...args) {
       return JSON.stringify(args)
     })
-    it('should support object', async () => {
+    it('should support key-value arguments', async () => {
       const src = `{{ "a" | obj_test: k1: "v1", k2: foo }}`
       const dst = '["a",["k1","v1"],["k2","bar"]]'
       const html = await liquid.parseAndRender(src, { foo: 'bar' })
       return expect(html).to.equal(dst)
     })
-    it('should support mixed object', async () => {
+    it('should support mixed arguments', async () => {
       const src = `{{ "a" | obj_test: "something", k1: "v1", k2: foo }}`
       const dst = '["a","something",["k1","v1"],["k2","bar"]]'
       const html = await liquid.parseAndRender(src, { foo: 'bar' })
       return expect(html).to.equal(dst)
     })
   })
+
+  describe('async filters', () => {
+    liquid.registerFilter('get_user_data', function (userId) {
+      return Promise.resolve({ userId, userName: userId.toUpperCase() })
+    })
+    it('should support async filter', async () => {
+      const src = `{{ userId | get_user_data | json }}`
+      const dst = '{"userId":"alice","userName":"ALICE"}'
+      const html = await liquid.parseAndRender(src, { userId: 'alice' })
+      return expect(html).to.equal(dst)
+    })
+  })
 })