fix: send $groupidentify for new groups even without properties

.changeset/warm-bears-glow.md

@@ -0,0 +1,5 @@
+---
+'posthog-js': patch
+---
+
+fix: send $groupidentify for new groups even when no properties are provided

packages/browser/playwright/mocked/group-analytics.spec.ts

@@ -24,7 +24,8 @@ test.describe('group analytics', () => {
         await page.locator('[data-cy-custom-event-button]').click()
 
         const capturedEvents = await page.capturedEvents()
-        expect(capturedEvents).toHaveLength(3)
+        // 4 events: $groupidentify (from group() call), $pageview, $pageleave, custom event
+        expect(capturedEvents).toHaveLength(4)
         const hasGroups = new Set(capturedEvents.map((x) => !!x.properties.$groups))
         expect(hasGroups).toEqual(new Set([true]))
     })

packages/browser/src/__tests__/posthog-core-also.test.ts

@@ -1258,7 +1258,19 @@ describe('posthog core', () => {
             expect(posthog.persistence!.props['$stored_group_properties']).toEqual(undefined)
         })
 
-        it('does not result in a capture call', () => {
+        it('sends $groupidentify for a new group even without properties', () => {
+            posthog.group('organization', 'org::5')
+
+            expect(posthog.capture).toHaveBeenCalledWith('$groupidentify', {
+                $group_type: 'organization',
+                $group_key: 'org::5',
+            })
+        })
+
+        it('does not send $groupidentify when group already exists with same key and no properties', () => {
+            posthog.group('organization', 'org::5')
+            jest.mocked(posthog.capture).mockClear()
+
             posthog.group('organization', 'org::5')
 
             expect(posthog.capture).not.toHaveBeenCalled()
@@ -1281,7 +1293,7 @@ describe('posthog core', () => {
             expect(posthog.reloadFeatureFlags).toHaveBeenCalledTimes(3)
         })
 
-        it('captures $groupidentify event', () => {
+        it('captures $groupidentify event with $group_set when properties provided', () => {
             posthog.group('organization', 'org::5', { group: 'property', foo: 5 })
 
             expect(posthog.capture).toHaveBeenCalledWith('$groupidentify', {
@@ -1294,6 +1306,19 @@ describe('posthog core', () => {
             })
         })
 
+        it('sends $groupidentify with $group_set for an existing group when properties provided', () => {
+            posthog.group('organization', 'org::5')
+            jest.mocked(posthog.capture).mockClear()
+
+            posthog.group('organization', 'org::5', { name: 'PostHog' })
+
+            expect(posthog.capture).toHaveBeenCalledWith('$groupidentify', {
+                $group_type: 'organization',
+                $group_key: 'org::5',
+                $group_set: { name: 'PostHog' },
+            })
+        })
+
         describe('subsequent capture calls', () => {
             beforeEach(() => {
                 posthog = defaultPostHog().init(
@@ -1316,9 +1341,10 @@ describe('posthog core', () => {
 
                 posthog.capture('some_event', { prop: 5 })
 
-                expect(posthog._requestQueue!.enqueue).toHaveBeenCalledTimes(1)
+                // 2 $groupidentify calls from group() + 1 some_event
+                expect(posthog._requestQueue!.enqueue).toHaveBeenCalledTimes(3)
 
-                const eventPayload = jest.mocked(posthog._requestQueue!.enqueue).mock.calls[0][0]
+                const eventPayload = jest.mocked(posthog._requestQueue!.enqueue).mock.calls[2][0]
                 // need to help TS know event payload data is not an array
                 // eslint-disable-next-line posthog-js/no-direct-array-check
                 if (Array.isArray(eventPayload.data!)) {

packages/browser/src/posthog-core.ts

@@ -2540,26 +2540,36 @@ export class PostHog implements PostHogInterface {
         }
 
         const existingGroups = this.getGroups()
+        const isNewGroup = existingGroups[groupType] !== groupKey
 
         // if group key changes, remove stored group properties
-        if (existingGroups[groupType] !== groupKey) {
+        if (isNewGroup) {
             this.resetGroupPropertiesForFlags(groupType)
         }
 
         this.register({ $groups: { ...existingGroups, [groupType]: groupKey } })
 
-        if (groupPropertiesToSet) {
-            this.capture(EVENT_GROUPIDENTIFY, {
+        // Send $groupidentify when the group is new/changed OR when properties
+        // are provided. Skip only when the group already exists with the same
+        // key and no new properties are being set.
+        if (isNewGroup || groupPropertiesToSet) {
+            const groupIdentifyProperties: Properties = {
                 $group_type: groupType,
                 $group_key: groupKey,
-                $group_set: groupPropertiesToSet,
-            })
+            }
+            if (groupPropertiesToSet) {
+                groupIdentifyProperties.$group_set = groupPropertiesToSet
+            }
+            this.capture(EVENT_GROUPIDENTIFY, groupIdentifyProperties)
+        }
+
+        if (groupPropertiesToSet) {
             this.setGroupPropertiesForFlags({ [groupType]: groupPropertiesToSet })
         }
 
         // If groups change and no properties change, reload feature flags.
         // The property change reload case is handled in setGroupPropertiesForFlags.
-        if (existingGroups[groupType] !== groupKey && !groupPropertiesToSet) {
+        if (isNewGroup && !groupPropertiesToSet) {
             this.reloadFeatureFlags()
         }
     }