fix: allow changing person properties after identify

CHANGELOG.md

@@ -1,5 +1,7 @@
 ## Next
 
+- fix: allow changing person properties after identify ([#205](https://github.com/PostHog/posthog-android/pull/205)) 
+
 ## 3.9.1 - 2024-11-11
 
 - recording: fix observation on multiple threads in layout/draw is not supported for compose ([#204](https://github.com/PostHog/posthog-android/pull/204))

posthog/src/main/java/com/posthog/PostHog.kt

@@ -556,7 +556,8 @@ public class PostHog private constructor(
             config?.logger?.log("identify called with invalid anonymousId: $anonymousId.")
         }
 
-        if (previousDistinctId != distinctId && !isIdentified) {
+        val hasDifferentDistinctId = previousDistinctId != distinctId
+        if (hasDifferentDistinctId && !isIdentified) {
             // this has to be set before capture since this flag will be read during the event
             // capture
             synchronized(identifiedLock) {
@@ -583,6 +584,16 @@ public class PostHog private constructor(
             if (reloadFeatureFlags) {
                 reloadFeatureFlags()
             }
+            // we need to make sure the user props update is for the same user
+            // otherwise they have to reset and identify again
+        } else if (!hasDifferentDistinctId && (userProperties?.isNotEmpty() == true || userPropertiesSetOnce?.isNotEmpty() == true)) {
+            capture(
+                "\$set",
+                distinctId = distinctId,
+                userProperties = userProperties,
+                userPropertiesSetOnce = userPropertiesSetOnce,
+            )
+            // Note we don't reload flags on property changes as these get processed async
         } else {
             config?.logger?.log("already identified with id: $distinctId.")
         }

posthog/src/test/java/com/posthog/PostHogTest.kt

@@ -574,13 +574,88 @@ internal class PostHogTest {
 
         sut.identify(
             "anotherDistinctId",
+        )
+
+        queueExecutor.shutdownAndAwaitTermination()
+
+        assertEquals(1, http.requestCount)
+
+        sut.close()
+    }
+
+    @Test
+    fun `captures a set event if identified`() {
+        val http = mockHttp()
+        val url = http.url("/")
+
+        val sut = getSut(url.toString(), preloadFeatureFlags = false, reloadFeatureFlags = false, flushAt = 2)
+
+        sut.identify(
+            DISTINCT_ID,
+            userProperties = userProps,
+            userPropertiesSetOnce = userPropsOnce,
+        )
+
+        val userProps = mapOf("user1" to "theResult")
+        val userPropsOnce = mapOf("logged" to false)
+
+        sut.identify(
+            DISTINCT_ID,
             userProperties = userProps,
             userPropertiesSetOnce = userPropsOnce,
         )
 
         queueExecutor.shutdownAndAwaitTermination()
 
-        assertEquals(1, http.requestCount)
+        val request = http.takeRequest()
+
+        val content = request.body.unGzip()
+        val batch = serializer.deserialize<PostHogBatchEvent>(content.reader())
+
+        val theEvent = batch.batch.last()
+
+        assertEquals("\$set", theEvent.event)
+        assertEquals(userProps, theEvent.properties!!["\$set"])
+        assertEquals(userPropsOnce, theEvent.properties!!["\$set_once"])
+
+        sut.close()
+    }
+
+    @Test
+    fun `does not capture a set event if different user`() {
+        val http = mockHttp()
+        val url = http.url("/")
+
+        val sut = getSut(url.toString(), preloadFeatureFlags = false, reloadFeatureFlags = false)
+
+        sut.identify(
+            DISTINCT_ID,
+            userProperties = userProps,
+            userPropertiesSetOnce = userPropsOnce,
+        )
+
+        val userProps = mapOf("user1" to "theResult")
+        val userPropsOnce = mapOf("logged" to false)
+
+        sut.identify(
+            "different user",
+            userProperties = userProps,
+            userPropertiesSetOnce = userPropsOnce,
+        )
+
+        queueExecutor.shutdownAndAwaitTermination()
+
+        queueExecutor.shutdownAndAwaitTermination()
+
+        val request = http.takeRequest()
+
+        val content = request.body.unGzip()
+        val batch = serializer.deserialize<PostHogBatchEvent>(content.reader())
+
+        val theEvent = batch.batch.last()
+
+        assertEquals(1, batch.batch.size)
+        assertEquals("\$identify", theEvent.event)
 
         sut.close()
     }