From b66e04e2626c3c53a55b36b3902fb4b07a109937 Mon Sep 17 00:00:00 2001
From: Rishabh Kumar <rishabh.kumar@prodigaltech.com>
Date: Mon, 24 Oct 2022 12:57:02 +0530
Subject: [PATCH 1/2] Remove void return in array from onePropertyDiff

---
 docs/api/tsOut_model.js.html | 3 ++-
 ts/model.ts                  | 3 ++-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/docs/api/tsOut_model.js.html b/docs/api/tsOut_model.js.html
index 55cc04f..32975cf 100644
--- a/docs/api/tsOut_model.js.html
+++ b/docs/api/tsOut_model.js.html
@@ -419,7 +419,8 @@ <h1 class="page-title">tsOut/model.js</h1>
     propertyDiff(key) {
         // TODO: determine if returning an array is really the best option
         if (key) {
-            return [this.onePropertyDiff(key)];
+            const diff = this.onePropertyDiff(key);
+            return diff ? [diff] : [];
         }
         else {
             const diffResult = [];
diff --git a/ts/model.ts b/ts/model.ts
index a0194c8..e7aea8e 100644
--- a/ts/model.ts
+++ b/ts/model.ts
@@ -541,7 +541,8 @@ abstract class NohmModel<TProps extends IDictionary = IDictionary> {
   ): Array<void | IPropertyDiff<keyof TProps>> {
     // TODO: determine if returning an array is really the best option
     if (key) {
-      return [this.onePropertyDiff(key)];
+      const diff = this.onePropertyDiff(key);
+      return diff ? [diff] : [];
     } else {
       const diffResult: Array<IPropertyDiff<keyof TProps>> = [];
       for (const [iterationKey] of this.properties) {

From 117c1c259df6397c30a6e45ed474ba9360726e05 Mon Sep 17 00:00:00 2001
From: Rishabh Kumar <rishabh.kumar@prodigaltech.com>
Date: Wed, 26 Oct 2022 18:58:16 +0530
Subject: [PATCH 2/2] Add tests and update return type

---
 test/typescript.test.ts | 19 +++++++++++++++++++
 ts/model.ts             |  2 +-
 2 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/test/typescript.test.ts b/test/typescript.test.ts
index 912f356..82eab51 100644
--- a/test/typescript.test.ts
+++ b/test/typescript.test.ts
@@ -391,3 +391,22 @@ test.serial('validation errors', async (t) => {
     }
   }
 });
+
+test.serial(
+  'return type',
+  async (t) => {
+    const testInstance = await nohm.factory<UserMockup>('UserMockup');
+    const diffBeforeUpdate = testInstance.propertyDiff('name');
+
+    // update the property
+    testInstance.property('name','testName');
+    const diffAfterUpdate = testInstance.propertyDiff('name');
+
+    t.deepEqual(diffBeforeUpdate, [], 'return without undefined');
+    t.deepEqual(diffAfterUpdate, [{
+      after: 'testName',
+      before: 'defaultName',
+      key: 'name',
+    }], 'return with difference in property');
+  },
+);
\ No newline at end of file
diff --git a/ts/model.ts b/ts/model.ts
index e7aea8e..3ab9c73 100644
--- a/ts/model.ts
+++ b/ts/model.ts
@@ -538,7 +538,7 @@ abstract class NohmModel<TProps extends IDictionary = IDictionary> {
    */
   public propertyDiff(
     key?: keyof TProps,
-  ): Array<void | IPropertyDiff<keyof TProps>> {
+  ): Array<IPropertyDiff<keyof TProps>> {
     // TODO: determine if returning an array is really the best option
     if (key) {
       const diff = this.onePropertyDiff(key);