remove useless hasOwnProperty calls, closes gcanti#423

Author: gcanti

CHANGELOG.md

@@ -14,6 +14,11 @@
 **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
+
+- **Polish**
+  - remove useless `hasOwnProperty` calls, closes #423 (@gcanti)
+
 # 2.1.1
 
 - **Bug Fix**

package.json

@@ -1,6 +1,6 @@
 {
   "name": "io-ts",
-  "version": "2.1.1",
+  "version": "2.1.2",
   "description": "TypeScript compatible runtime type system for IO validation",
   "files": [
     "lib",

src/index.ts

@@ -798,7 +798,7 @@ 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 (!hasOwnProperty.call(u, k) || !types[i].is(u[k])) {
+          if (!types[i].is(u[k])) {
             return false
           }
         }
@@ -812,20 +812,14 @@ export const type = <P extends Props>(props: P, name: string = getInterfaceTypeN
         const errors: Errors = []
         for (let i = 0; i < len; i++) {
           const k = keys[i]
-          if (!hasOwnProperty.call(a, k)) {
-            if (a === o) {
-              a = { ...o }
-            }
-            a[k] = a[k]
-          }
           const ak = a[k]
           const type = types[i]
           const result = type.validate(ak, appendContext(c, k, type, ak))
           if (isLeft(result)) {
             pushAll(errors, result.left)
           } else {
             const vak = result.right
-            if (vak !== ak) {
+            if (vak !== ak || (vak === undefined && !hasOwnProperty.call(a, k))) {
               /* istanbul ignore next */
               if (a === o) {
                 a = { ...o }

test/strict.ts

@@ -29,6 +29,19 @@ describe('strict', () => {
       assert.strictEqual(T.is({ a: 1, b: 1 }), true)
       assert.strictEqual(T.is(undefined), false)
     })
+
+    it('#423', () => {
+      class A {
+        get a() {
+          return 'a'
+        }
+        get b() {
+          return 'b'
+        }
+      }
+      const T = t.strict({ a: t.string, b: t.string })
+      assert.strictEqual(T.is(new A()), true)
+    })
   })
 
   describe('decode', () => {
@@ -57,6 +70,19 @@ describe('strict', () => {
       const T = t.strict({ foo: t.string })
       assertSuccess(T.decode({ foo: 'foo', bar: 1, baz: true }), { foo: 'foo' })
     })
+
+    it('#423', () => {
+      class A {
+        get a() {
+          return 'a'
+        }
+        get b() {
+          return 'b'
+        }
+      }
+      const T = t.strict({ a: t.string, b: t.string })
+      assertSuccess(T.decode(new A()))
+    })
   })
 
   describe('encode', () => {

test/type.ts

@@ -35,6 +35,19 @@ describe('type', () => {
       const T = t.type({ a: t.string })
       assert.strictEqual(T.is({ a: 'a', b: 1 }), true)
     })
+
+    it('#423', () => {
+      class A {
+        get a() {
+          return 'a'
+        }
+        get b() {
+          return 'b'
+        }
+      }
+      const T = t.type({ a: t.string, b: t.string })
+      assert.strictEqual(T.is(new A()), true)
+    })
   })
 
   describe('decode', () => {
@@ -75,6 +88,19 @@ describe('type', () => {
       const T = t.interface({ a: t.string })
       assertSuccess(T.decode({ a: 'a' }))
     })
+
+    it('#423', () => {
+      class A {
+        get a() {
+          return 'a'
+        }
+        get b() {
+          return 'b'
+        }
+      }
+      const T = t.type({ a: t.string, b: t.string })
+      assertSuccess(T.decode(new A()))
+    })
   })
 
   describe('encode', () => {