feat: appropriate error for malformed filters, fixes #271

src/parser/tokenizer.ts

@@ -89,7 +89,8 @@ export class Tokenizer {
         ++this.p
         const arg = this.readFilterArg()
         arg && args.push(arg)
-        while (this.p < this.N && this.peek() !== ',' && this.peek() !== '|') ++this.p
+        this.skipBlank()
+        assert(this.end() || this.peek() === ',' || this.peek() === '|', () => `unexpected character ${this.snapshot()}`)
       } while (this.peek() === ',')
     }
     return new FilterToken(name.getText(), args, this.input, begin, this.p, this.file)

test/integration/builtin/filters/misc.ts

@@ -1,5 +1,8 @@
 import { Liquid } from '../../../../src/liquid'
-import { expect } from 'chai'
+import { expect, use } from 'chai'
+import * as chaiAsPromised from 'chai-as-promised'
+
+use(chaiAsPromised)
 
 describe('filters/object', function () {
   const liquid = new Liquid()
@@ -15,6 +18,10 @@ describe('filters/object', function () {
     it('should output false when allow_false=true', async () => expect(await liquid.parseAndRender('{{false | default: true, allow_false: true}}')).to.equal('false'))
     it('should output default without allow_false', async () => expect(await liquid.parseAndRender('{{false | default: true}}')).to.equal('true'))
     it('should output default when allow_false=false', async () => expect(await liquid.parseAndRender('{{false | default: true, allow_false: false}}')).to.equal('true'))
+    it('should throw for additional args', () => {
+      const src = `{{ age | default: 'now'  date: '%d'}}` // missing `|` before `date`
+      return expect(liquid.parseAndRender(src)).to.be.rejectedWith(/unexpected character "date: '%d'"/)
+    })
   })
   describe('json', function () {
     it('should stringify string', async () => expect(await liquid.parseAndRender('{{"foo" | json}}')).to.equal('"foo"'))