From ebfe260c7ab75b1c879245f9ea4893c872530f8f Mon Sep 17 00:00:00 2001
From: Kyle Peacock <kylpeacock@gmail.com>
Date: Wed, 14 Dec 2022 16:45:03 -0800
Subject: [PATCH] simple test

---
 packages/candid/src/idl.test.ts | 29 ++++++++++++++++++++++++++++-
 packages/candid/src/idl.ts      | 14 ++++++++++----
 2 files changed, 38 insertions(+), 5 deletions(-)

diff --git a/packages/candid/src/idl.test.ts b/packages/candid/src/idl.test.ts
index 7ab98b6b0..31a3edfb1 100644
--- a/packages/candid/src/idl.test.ts
+++ b/packages/candid/src/idl.test.ts
@@ -180,7 +180,9 @@ test('IDL encoding (arraybuffer)', () => {
   IDL.encode([IDL.Vec(IDL.Nat8)], [new Uint8Array()]);
   IDL.encode([IDL.Vec(IDL.Nat8)], [new Uint8Array(100).fill(42)]);
   IDL.encode([IDL.Vec(IDL.Nat16)], [new Uint16Array(200).fill(42)]);
-  expect(() => IDL.encode([IDL.Vec(IDL.Int8)], [new Uint16Array(10).fill(420)])).toThrow(/Invalid vec int8 argument/);
+  expect(() => IDL.encode([IDL.Vec(IDL.Int8)], [new Uint16Array(10).fill(420)])).toThrow(
+    /Invalid vec int8 argument/,
+  );
 });
 
 test('IDL encoding (array)', () => {
@@ -641,6 +643,31 @@ test('decode / encode unknown nested record', () => {
   expect(decodedValue2).toEqual(value);
 });
 
+test.only('should allow records with missing optional fields', () => {
+  const ExtendedRecord = IDL.Record({
+    foo: IDL.Int32,
+    bar: IDL.Bool,
+    bool: IDL.Opt(IDL.Bool),
+    int: IDL.Opt(IDL.Int),
+    nat: IDL.Opt(IDL.Nat),
+    nat32: IDL.Opt(IDL.Nat32),
+    nat64: IDL.Opt(IDL.Nat64),
+    float32: IDL.Opt(IDL.Float32),
+    float64: IDL.Opt(IDL.Float64),
+    text: IDL.Opt(IDL.Text),
+    null: IDL.Opt(IDL.Null),
+    reserved: IDL.Opt(IDL.Reserved),
+    principal: IDL.Opt(IDL.Principal),
+    nested: IDL.Opt(IDL.Opt(IDL.Nat)),
+  });
+
+  const encoded = IDL.encode([ExtendedRecord], [{ foo: 42, bar: true }]);
+
+  expect(toHexString(encoded)).toMatchInlineSnapshot(
+    `"4449444c0d6e7c6e7d6e686e7e6e7f6e716e706e016e796e786e736e726c0ed3e3aa027e868eb70275ef99c00200e199cf0201ae9db1900102aa88ee88040387bdbac80404ad99e7e70405a8ed97f50406f7ddd8f80607c0e7a6b40908dfeca6b40909bba2a2d00e0adaa7a2d00e0b010c012a000000000000000000000000000000"`,
+  );
+});
+
 test('should correctly decode expected optional fields with lower hash than required fields', () => {
   const HttpResponse = IDL.Record({
     body: IDL.Text,
diff --git a/packages/candid/src/idl.ts b/packages/candid/src/idl.ts
index 4b246da05..04ab81222 100644
--- a/packages/candid/src/idl.ts
+++ b/packages/candid/src/idl.ts
@@ -48,7 +48,9 @@ const magicNumber = 'DIDL';
 const toReadableString_max = 400; // will not display arguments after 400chars. Makes sure 2mb blobs don't get inside the error
 
 function zipWith<TX, TY, TR>(xs: TX[], ys: TY[], f: (a: TX, b: TY) => TR): TR[] {
-  return xs.map((x, i) => f(x, ys[i]));
+  return xs.map((x, i) => {
+    return f(x, ys[i]);
+  });
 }
 
 /**
@@ -978,9 +980,13 @@ export class RecordClass extends ConstructType<Record<string, any>> {
     if (
       typeof x === 'object' &&
       this._fields.every(([k, t]) => {
-        // eslint-disable-next-line
-        if (!x.hasOwnProperty(k)) {
-          throw new Error(`Record is missing key "${k}".`);
+        if (!(k in x)) {
+          // Allow missing optional fields.
+          if (t instanceof OptClass) {
+            x[k] = [];
+          } else {
+            throw new Error(`Record is missing key "${k}".`);
+          }
         }
         try {
           return t.covariant(x[k]);