From 4f85b53e013dda15211b79c798294af423ba5267 Mon Sep 17 00:00:00 2001
From: Serhii Kulykov <iamkulykov@gmail.com>
Date: Tue, 21 Jan 2020 16:16:26 +0200
Subject: [PATCH] fix: prevent incorrect console warning (#162)

---
 src/vaadin-checkbox-group.html       |  6 +++++-
 test/vaadin-checkbox-group_test.html | 32 ++++++++++++++++++++++++++++
 2 files changed, 37 insertions(+), 1 deletion(-)

diff --git a/src/vaadin-checkbox-group.html b/src/vaadin-checkbox-group.html
index f88c650..dff2c66 100644
--- a/src/vaadin-checkbox-group.html
+++ b/src/vaadin-checkbox-group.html
@@ -211,7 +211,11 @@
               }
             });
 
-            if (addedCheckboxes.some(checkbox => !checkbox.hasAttribute('value'))) {
+            const hasValue = checkbox => {
+              const {value} = checkbox;
+              return checkbox.hasAttribute('value') || value && value !== 'on';
+            };
+            if (!addedCheckboxes.every(hasValue)) {
               console.warn('Please add value attribute to all checkboxes in checkbox group');
             }
           });
diff --git a/test/vaadin-checkbox-group_test.html b/test/vaadin-checkbox-group_test.html
index 144549d..70cdcdd 100644
--- a/test/vaadin-checkbox-group_test.html
+++ b/test/vaadin-checkbox-group_test.html
@@ -280,6 +280,38 @@
 
       expect(spy).to.not.be.called;
     });
+
+    it('should warn when adding checkbox without value', () => {
+      sinon.stub(console, 'warn');
+
+      const checkbox = document.createElement('vaadin-checkbox');
+      vaadinCheckboxGroup.appendChild(checkbox);
+      vaadinCheckboxGroup._observer.flush();
+      expect(console.warn.callCount).to.equal(1);
+      console.warn.restore();
+    });
+
+    it('should not warn when adding checkbox with value attribute', () => {
+      sinon.stub(console, 'warn');
+
+      const checkbox = document.createElement('vaadin-checkbox');
+      checkbox.setAttribute('value', 'something');
+      vaadinCheckboxGroup.appendChild(checkbox);
+      vaadinCheckboxGroup._observer.flush();
+      expect(console.warn.callCount).to.equal(0);
+      console.warn.restore();
+    });
+
+    it('should not warn when adding checkbox with value property', () => {
+      sinon.stub(console, 'warn');
+
+      const checkbox = document.createElement('vaadin-checkbox');
+      checkbox.value = 'something';
+      vaadinCheckboxGroup.appendChild(checkbox);
+      vaadinCheckboxGroup._observer.flush();
+      expect(console.warn.callCount).to.equal(0);
+      console.warn.restore();
+    });
   });
 
   describe('vaadin-checkbox-group validation', () => {