fix regression in v2.1.2

Author: gcanti

CHANGELOG.md

@@ -14,7 +14,7 @@
 **Note**: Gaps between patch versions are faulty/broken releases. **Note**: A feature tagged as Experimental is in a
 high state of flux, you're at risk of it changing without notice.
 
-# 2.1.2
+# 2.1.3
 
 - **Polish**
   - remove useless `hasOwnProperty` calls, closes #423 (@gcanti)

package.json

@@ -1,6 +1,6 @@
 {
   "name": "io-ts",
-  "version": "2.1.2",
+  "version": "2.1.3",
   "description": "TypeScript compatible runtime type system for IO validation",
   "files": [
     "lib",

src/index.ts

@@ -798,7 +798,8 @@ export const type = <P extends Props>(props: P, name: string = getInterfaceTypeN
       if (UnknownRecord.is(u)) {
         for (let i = 0; i < len; i++) {
           const k = keys[i]
-          if (!types[i].is(u[k])) {
+          const uk = u[k]
+          if ((uk === undefined && !hasOwnProperty.call(u, k)) || !types[i].is(uk)) {
             return false
           }
         }

test/type.ts

@@ -31,6 +31,12 @@ describe('type', () => {
       assert.strictEqual(T.is([]), false)
     })
 
+    // #434
+    it('should return `false` on missing fields', () => {
+      const T = t.type({ a: t.unknown })
+      assert.strictEqual(T.is({}), false)
+    })
+
     it('should allow additional properties', () => {
       const T = t.type({ a: t.string })
       assert.strictEqual(T.is({ a: 'a', b: 1 }), true)