From bf93bdea48ff423d4cbb910f18c0f2c8af347ff7 Mon Sep 17 00:00:00 2001
From: Anthony Gubler <agubler@sitepen.com>
Date: Tue, 5 Nov 2019 12:57:50 +0000
Subject: [PATCH 1/3] failing unit test for diff property on the first render

---
 tests/core/unit/vdom.tsx | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/tests/core/unit/vdom.tsx b/tests/core/unit/vdom.tsx
index 20d26aeb8..325730824 100644
--- a/tests/core/unit/vdom.tsx
+++ b/tests/core/unit/vdom.tsx
@@ -3841,6 +3841,29 @@ jsdomDescribe('vdom', () => {
 						resolvers.resolve();
 						assert.strictEqual(root.outerHTML, '<div><div><button></button><div>first</div></div></div>');
 					});
+
+					it('should call diff property for the first render', () => {
+						const createWidget = create({ diffProperty });
+						let counter = 0;
+						const Foo = createWidget(({ middleware }) => {
+							middleware.diffProperty('key', () => {
+								counter++;
+							});
+							return v('div', [`${counter}`]);
+						});
+						const App = createWidget(() => {
+							return v('div', [
+								v('button', {
+								}),
+								Foo({ key: 'foo' })
+							]);
+						});
+						const r = renderer(() => App({}));
+						const root = document.createElement('div');
+						r.mount({ domNode: root });
+						assert.strictEqual(root.outerHTML, '<div><div><button></button><div>1</div></div></div>');
+						sendEvent(root.childNodes[0].childNodes[0] as HTMLButtonElement, 'click');
+					});
 				});
 			});
 		});

From 13a9b6bc94e22d470a8bb528c6a9f592d8de2033 Mon Sep 17 00:00:00 2001
From: Anthony Gubler <agubler@sitepen.com>
Date: Tue, 5 Nov 2019 13:02:16 +0000
Subject: [PATCH 2/3] Call diff properties immediately when they are registered

---
 src/core/vdom.ts         | 1 +
 tests/core/unit/vdom.tsx | 1 -
 2 files changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/core/vdom.ts b/src/core/vdom.ts
index 7f4a09fd7..dd694ec93 100644
--- a/src/core/vdom.ts
+++ b/src/core/vdom.ts
@@ -878,6 +878,7 @@ export const diffProperty = factory(({ id }) => {
 			widgetMeta.customDiffProperties = widgetMeta.customDiffProperties || new Set();
 			const propertyDiffMap = widgetMeta.customDiffMap.get(id) || new Map();
 			if (!propertyDiffMap.has(propertyName)) {
+				diff({}, widgetMeta.properties);
 				propertyDiffMap.set(propertyName, diff);
 				widgetMeta.customDiffProperties.add(propertyName);
 			}
diff --git a/tests/core/unit/vdom.tsx b/tests/core/unit/vdom.tsx
index 325730824..4469ab63d 100644
--- a/tests/core/unit/vdom.tsx
+++ b/tests/core/unit/vdom.tsx
@@ -3790,7 +3790,6 @@ jsdomDescribe('vdom', () => {
 						let counter = 0;
 						const Foo = createWidget(({ middleware }) => {
 							middleware.diffProperty('key', (current: any, properties: any) => {
-								assert.deepEqual(current, { key: 'foo' });
 								assert.deepEqual(properties, { key: 'foo' });
 								middleware.invalidator();
 							});

From 0b2c1c6dc313c9213cbb17c68d68bbda16faf2ce Mon Sep 17 00:00:00 2001
From: Anthony Gubler <agubler@sitepen.com>
Date: Tue, 5 Nov 2019 13:07:02 +0000
Subject: [PATCH 3/3] prettier

---
 tests/core/unit/vdom.tsx | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/tests/core/unit/vdom.tsx b/tests/core/unit/vdom.tsx
index 4469ab63d..bef7a638f 100644
--- a/tests/core/unit/vdom.tsx
+++ b/tests/core/unit/vdom.tsx
@@ -3851,11 +3851,7 @@ jsdomDescribe('vdom', () => {
 							return v('div', [`${counter}`]);
 						});
 						const App = createWidget(() => {
-							return v('div', [
-								v('button', {
-								}),
-								Foo({ key: 'foo' })
-							]);
+							return v('div', [v('button', {}), Foo({ key: 'foo' })]);
 						});
 						const r = renderer(() => App({}));
 						const root = document.createElement('div');