fix: reading .first, .last of Array, closes #175

src/context/context.ts

@@ -123,11 +123,23 @@ function readProperty (obj: Scope, key: string) {
     if (obj.hasOwnProperty(key)) return obj[key]
     return obj.liquidMethodMissing(key)
   }
-  return key === 'size' ? readSize(obj) : obj[key]
+  if (key === 'size') return readSize(obj)
+  if (key === 'first') return readFirst(obj)
+  if (key === 'last') return readLast(obj)
+  return obj[key]
+}
+
+function readFirst (obj: Scope) {
+  if (_.isArray(obj)) return obj[0]
+  return obj['first']
+}
+
+function readLast (obj: Scope) {
+  if (_.isArray(obj)) return obj[obj.length - 1]
+  return obj['last']
 }
 
 function readSize (obj: Scope) {
-  if (!_.isNil(obj['size'])) return obj['size']
   if (_.isArray(obj) || _.isString(obj)) return obj.length
   return obj['size']
 }

test/unit/context/context.ts

@@ -11,6 +11,10 @@ describe('Context', function () {
       foo: 'zoo',
       one: 1,
       zoo: { size: 4 },
+      obj: {
+        first: 'f',
+        last: 'l'
+      },
       bar: {
         zoo: 'coo',
         'Mr.Smith': 'John',
@@ -124,6 +128,18 @@ describe('Context', function () {
     it('should return undefined if do not have size and length', async function () {
       expect(ctx.get('one.size')).to.equal(undefined)
     })
+    it('should read .first of array', async function () {
+      expect(ctx.get('bar.arr.first')).to.equal('a')
+    })
+    it('should read .first of object', async function () {
+      expect(ctx.get('obj.first')).to.equal('f')
+    })
+    it('should read .last of array', async function () {
+      expect(ctx.get('bar.arr.last')).to.equal('b')
+    })
+    it('should read .last of object', async function () {
+      expect(ctx.get('obj.last')).to.equal('l')
+    })
   })
   describe('strictVariables', async function () {
     let ctx: Context