Move fragment auto span finish to onFragmentStarted (#3424)

* moved fragment auto span finish to onFragmentStarted instead of onFragmentResumed to account for ViewPager2 behaviour

Author: stefanosiano

CHANGELOG.md

@@ -4,6 +4,7 @@
 
 ### Fixes
 
+- Move fragment auto span finish to onFragmentStarted ([#3424](https://github.com/getsentry/sentry-java/pull/3424))
 - Remove profiling timeout logic and disable profiling on API 21 ([#3478](https://github.com/getsentry/sentry-java/pull/3478))
 - Properly reset metric flush flag on metric emission ([#3493](https://github.com/getsentry/sentry-java/pull/3493))
 

sentry-android-fragment/src/main/java/io/sentry/android/fragment/SentryFragmentLifecycleCallbacks.kt

@@ -96,12 +96,13 @@ class SentryFragmentLifecycleCallbacks(
 
     override fun onFragmentStarted(fragmentManager: FragmentManager, fragment: Fragment) {
         addBreadcrumb(fragment, FragmentLifecycleState.STARTED)
+
+        // ViewPager2 locks background fragments to STARTED state
+        stopTracing(fragment)
     }
 
     override fun onFragmentResumed(fragmentManager: FragmentManager, fragment: Fragment) {
         addBreadcrumb(fragment, FragmentLifecycleState.RESUMED)
-
-        stopTracing(fragment)
     }
 
     override fun onFragmentPaused(fragmentManager: FragmentManager, fragment: Fragment) {

sentry-android-fragment/src/test/java/io/sentry/android/fragment/SentryFragmentLifecycleCallbacksTest.kt

@@ -229,11 +229,11 @@ class SentryFragmentLifecycleCallbacksTest {
     }
 
     @Test
-    fun `When fragment is resumed, it should stop tracing if enabled`() {
+    fun `When fragment is started, it should stop tracing if enabled`() {
         val sut = fixture.getSut(enableAutoFragmentLifecycleTracing = true)
 
         sut.onFragmentCreated(fixture.fragmentManager, fixture.fragment, savedInstanceState = null)
-        sut.onFragmentResumed(fixture.fragmentManager, fixture.fragment)
+        sut.onFragmentStarted(fixture.fragmentManager, fixture.fragment)
 
         verify(fixture.span).finish(
             check {
@@ -243,12 +243,12 @@ class SentryFragmentLifecycleCallbacksTest {
     }
 
     @Test
-    fun `When fragment is resumed, it should stop tracing if enabled but keep status`() {
+    fun `When fragment is started, it should stop tracing if enabled but keep status`() {
         val sut = fixture.getSut(enableAutoFragmentLifecycleTracing = true)
 
         whenever(fixture.span.status).thenReturn(SpanStatus.ABORTED)
         sut.onFragmentCreated(fixture.fragmentManager, fixture.fragment, savedInstanceState = null)
-        sut.onFragmentResumed(fixture.fragmentManager, fixture.fragment)
+        sut.onFragmentStarted(fixture.fragmentManager, fixture.fragment)
 
         verify(fixture.span).finish(
             check {