added support to additionalItems property in array object (#322)

Author: KiraPC

index.js

@@ -980,9 +980,9 @@ function buildArray (location, code, name, key = null) {
   }
 
   let result = { code: '', laterCode: '' }
+  const accessor = '[i]'
   if (Array.isArray(schema.items)) {
     result = schema.items.reduce((res, item, i) => {
-      const accessor = '[i]'
       const tmpRes = nested(laterCode, name, accessor, mergeLocation(location, { schema: item }), i, true)
       const condition = `i === ${i} && ${buildArrayTypeCondition(item.type, accessor)}`
       return {
@@ -994,13 +994,23 @@ function buildArray (location, code, name, key = null) {
         ${tmpRes.laterCode}`
       }
     }, result)
+
+    if (schema.additionalItems) {
+      const tmpRes = nested(laterCode, name, accessor, mergeLocation(location, { schema: schema.items }), undefined, true)
+      result.code += `
+      else if (i >= ${schema.items.length}) {
+        ${tmpRes.code}
+      }
+      `
+    }
+
     result.code += `
     else {
       throw new Error(\`Item at $\{i} does not match schema definition.\`)
     }
     `
   } else {
-    result = nested(laterCode, name, '[i]', mergeLocation(location, { schema: schema.items }), undefined, true)
+    result = nested(laterCode, name, accessor, mergeLocation(location, { schema: schema.items }), undefined, true)
   }
 
   if (key) {

test/array.test.js

@@ -210,6 +210,69 @@ buildTest({
   foo: [1, 'string', {}, null]
 })
 
+test('array items is a list of schema and additionalItems is true, just the described item is validated', (t) => {
+  t.plan(1)
+
+  const schema = {
+    type: 'object',
+    properties: {
+      foo: {
+        type: 'array',
+        items: [
+          {
+            type: 'string'
+          }
+        ],
+        additionalItems: true
+      }
+    }
+  }
+
+  const stringify = build(schema)
+  const result = stringify({
+    foo: [
+      'foo',
+      'bar',
+      1
+    ]
+  })
+
+  t.equal(result, '{"foo":["foo","bar",1]}')
+})
+
+test('array items is a list of schema and additionalItems is false', (t) => {
+  t.plan(1)
+
+  const schema = {
+    type: 'object',
+    properties: {
+      foo: {
+        type: 'array',
+        items: [
+          {
+            type: 'string'
+          }
+        ],
+        additionalItems: false
+      }
+    }
+  }
+
+  const stringify = build(schema)
+
+  try {
+    stringify({
+      foo: [
+        'foo',
+        'bar'
+      ]
+    })
+    t.fail()
+  } catch (error) {
+    t.ok(/does not match schema definition./.test(error.message))
+  }
+})
+
 // https://github.com/fastify/fast-json-stringify/issues/279
 test('object array with anyOf and symbol', (t) => {
   t.plan(1)