fix(android-fragment): support detach/attach navigation in fragment tracing

CHANGELOG.md

@@ -8,6 +8,7 @@
 
 ### Fixes
 
+- Fix fragment tracing not working with detach/attach navigation ([#5660](https://github.com/getsentry/sentry-java/pull/5660))
 - Fix potential NPE within `Scope.endSession()` ([#5657](https://github.com/getsentry/sentry-java/pull/5657))
 
 ### Performance

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

@@ -93,17 +93,32 @@ public class SentryFragmentLifecycleCallbacks(
     savedInstanceState: Bundle?,
   ) {
     addBreadcrumb(fragment, FragmentLifecycleState.VIEW_CREATED)
+
+    // For detach/attach navigation (e.g. manual tab switching, ViewPager v1 with
+    // FragmentPagerAdapter, custom navigation frameworks), onFragmentCreated is never called for
+    // off-screen fragments that are re-attached. Starting here enables a narrower
+    // "view created -> resumed" span for those paths. startTracing is idempotent, so for the
+    // normal onFragmentCreated -> onFragmentViewCreated path this is a no-op.
+    if (fragment.isAdded) {
+      startTracing(fragment)
+    }
   }
 
   override fun onFragmentStarted(fragmentManager: FragmentManager, fragment: Fragment) {
     addBreadcrumb(fragment, FragmentLifecycleState.STARTED)
 
-    // ViewPager2 locks background fragments to STARTED state
+    // ViewPager2 locks background fragments to STARTED state, so we stop here to avoid
+    // spans hanging for off-screen fragments that never reach RESUMED.
     stopTracing(fragment)
   }
 
   override fun onFragmentResumed(fragmentManager: FragmentManager, fragment: Fragment) {
     addBreadcrumb(fragment, FragmentLifecycleState.RESUMED)
+
+    // For detach/attach navigation, onFragmentStarted may not fire before onFragmentResumed.
+    // If a span is still running here, stop it now. stopTracing is idempotent, so this is a
+    // no-op for the normal path where onFragmentStarted already stopped the span.
+    stopTracing(fragment)
   }
 
   override fun onFragmentPaused(fragmentManager: FragmentManager, fragment: Fragment) {
@@ -116,6 +131,10 @@ public class SentryFragmentLifecycleCallbacks(
 
   override fun onFragmentViewDestroyed(fragmentManager: FragmentManager, fragment: Fragment) {
     addBreadcrumb(fragment, FragmentLifecycleState.VIEW_DESTROYED)
+
+    // Failsafe: cancel any span that didn't finish via the normal started/resumed path
+    // (e.g. fragment view destroyed before reaching STARTED or RESUMED).
+    stopTracing(fragment)
   }
 
   override fun onFragmentDestroyed(fragmentManager: FragmentManager, fragment: Fragment) {

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

@@ -251,6 +251,85 @@ class SentryFragmentLifecycleCallbacksTest {
     verify(fixture.span).finish(check { assertEquals(SpanStatus.OK, it) })
   }
 
+  @Test
+  fun `When fragment view is created via detach-attach, it should start tracing if enabled`() {
+    // Simulates detach/attach navigation: onFragmentCreated is NOT called, only
+    // onFragmentViewCreated
+    val sut = fixture.getSut(enableAutoFragmentLifecycleTracing = true)
+
+    sut.onFragmentViewCreated(
+      fixture.fragmentManager,
+      fixture.fragment,
+      view = mock(),
+      savedInstanceState = null,
+    )
+
+    verify(fixture.transaction)
+      .startChild(
+        check<String> { assertEquals(SentryFragmentLifecycleCallbacks.FRAGMENT_LOAD_OP, it) },
+        check<String> { assertEquals("androidx.fragment.app.Fragment", it) },
+      )
+  }
+
+  @Test
+  fun `When fragment view is created after onFragmentCreated, it should not start a second span`() {
+    // Normal path: onFragmentCreated already started the span; onFragmentViewCreated is a no-op
+    val sut = fixture.getSut(enableAutoFragmentLifecycleTracing = true)
+
+    sut.onFragmentCreated(fixture.fragmentManager, fixture.fragment, savedInstanceState = null)
+    sut.onFragmentViewCreated(
+      fixture.fragmentManager,
+      fixture.fragment,
+      view = mock(),
+      savedInstanceState = null,
+    )
+
+    verify(fixture.transaction).startChild(any<String>(), any<String>())
+  }
+
+  @Test
+  fun `When fragment is resumed, it should stop tracing if span is still running`() {
+    // Simulates detach/attach path where onFragmentStarted may be skipped
+    val sut = fixture.getSut(enableAutoFragmentLifecycleTracing = true)
+
+    sut.onFragmentViewCreated(
+      fixture.fragmentManager,
+      fixture.fragment,
+      view = mock(),
+      savedInstanceState = null,
+    )
+    sut.onFragmentResumed(fixture.fragmentManager, fixture.fragment)
+
+    verify(fixture.span).finish(check { assertEquals(SpanStatus.OK, it) })
+  }
+
+  @Test
+  fun `When fragment is resumed after started, it should not double-finish the span`() {
+    // Normal path: onFragmentStarted already stopped the span; onFragmentResumed is a no-op
+    val sut = fixture.getSut(enableAutoFragmentLifecycleTracing = true)
+
+    sut.onFragmentCreated(fixture.fragmentManager, fixture.fragment, savedInstanceState = null)
+    sut.onFragmentStarted(fixture.fragmentManager, fixture.fragment)
+    sut.onFragmentResumed(fixture.fragmentManager, fixture.fragment)
+
+    verify(fixture.span).finish(any())
+  }
+
+  @Test
+  fun `When fragment view is destroyed before started, it should stop tracing as failsafe`() {
+    val sut = fixture.getSut(enableAutoFragmentLifecycleTracing = true)
+
+    sut.onFragmentViewCreated(
+      fixture.fragmentManager,
+      fixture.fragment,
+      view = mock(),
+      savedInstanceState = null,
+    )
+    sut.onFragmentViewDestroyed(fixture.fragmentManager, fixture.fragment)
+
+    verify(fixture.span).finish(check { assertEquals(SpanStatus.OK, it) })
+  }
+
   private fun verifyBreadcrumbAdded(expectedState: String) {
     verify(fixture.scopes)
       .addBreadcrumb(
@@ -265,6 +344,85 @@ class SentryFragmentLifecycleCallbacksTest {
       )
   }
 
+  @Test
+  fun `When fragment view is created via detach-attach, it should start tracing if enabled`() {
+    // Simulates detach/attach navigation: onFragmentCreated is NOT called, only
+    // onFragmentViewCreated
+    val sut = fixture.getSut(enableAutoFragmentLifecycleTracing = true)
+
+    sut.onFragmentViewCreated(
+      fixture.fragmentManager,
+      fixture.fragment,
+      view = mock(),
+      savedInstanceState = null,
+    )
+
+    verify(fixture.transaction)
+      .startChild(
+        check<String> { assertEquals(SentryFragmentLifecycleCallbacks.FRAGMENT_LOAD_OP, it) },
+        check<String> { assertEquals("androidx.fragment.app.Fragment", it) },
+      )
+  }
+
+  @Test
+  fun `When fragment view is created after onFragmentCreated, it should not start a second span`() {
+    // Normal path: onFragmentCreated already started the span; onFragmentViewCreated is a no-op
+    val sut = fixture.getSut(enableAutoFragmentLifecycleTracing = true)
+
+    sut.onFragmentCreated(fixture.fragmentManager, fixture.fragment, savedInstanceState = null)
+    sut.onFragmentViewCreated(
+      fixture.fragmentManager,
+      fixture.fragment,
+      view = mock(),
+      savedInstanceState = null,
+    )
+
+    verify(fixture.transaction).startChild(any<String>(), any<String>())
+  }
+
+  @Test
+  fun `When fragment is resumed, it should stop tracing if span is still running`() {
+    // Simulates detach/attach path where onFragmentStarted may be skipped
+    val sut = fixture.getSut(enableAutoFragmentLifecycleTracing = true)
+
+    sut.onFragmentViewCreated(
+      fixture.fragmentManager,
+      fixture.fragment,
+      view = mock(),
+      savedInstanceState = null,
+    )
+    sut.onFragmentResumed(fixture.fragmentManager, fixture.fragment)
+
+    verify(fixture.span).finish(check { assertEquals(SpanStatus.OK, it) })
+  }
+
+  @Test
+  fun `When fragment is resumed after started, it should not double-finish the span`() {
+    // Normal path: onFragmentStarted already stopped the span; onFragmentResumed is a no-op
+    val sut = fixture.getSut(enableAutoFragmentLifecycleTracing = true)
+
+    sut.onFragmentCreated(fixture.fragmentManager, fixture.fragment, savedInstanceState = null)
+    sut.onFragmentStarted(fixture.fragmentManager, fixture.fragment)
+    sut.onFragmentResumed(fixture.fragmentManager, fixture.fragment)
+
+    verify(fixture.span).finish(any())
+  }
+
+  @Test
+  fun `When fragment view is destroyed before started, it should stop tracing as failsafe`() {
+    val sut = fixture.getSut(enableAutoFragmentLifecycleTracing = true)
+
+    sut.onFragmentViewCreated(
+      fixture.fragmentManager,
+      fixture.fragment,
+      view = mock(),
+      savedInstanceState = null,
+    )
+    sut.onFragmentViewDestroyed(fixture.fragmentManager, fixture.fragment)
+
+    verify(fixture.span).finish(check { assertEquals(SpanStatus.OK, it) })
+  }
+
   private fun verifyBreadcrumbAddedCount(count: Int) {
     verify(fixture.scopes, times(count)).addBreadcrumb(any<Breadcrumb>(), anyOrNull())
   }

sentry-samples/sentry-samples-android/src/main/AndroidManifest.xml

@@ -65,6 +65,10 @@
       android:name=".ThirdActivityFragment"
       android:exported="false" />
 
+    <activity
+      android:name=".DetachAttachTabsActivity"
+      android:exported="false" />
+
     <activity
       android:name=".GesturesActivity"
       android:exported="false" />

sentry-samples/sentry-samples-android/src/main/java/io/sentry/samples/android/DetachAttachTabsActivity.kt

@@ -0,0 +1,50 @@
+package io.sentry.samples.android
+
+import android.os.Bundle
+import android.view.View
+import android.widget.TextView
+import androidx.appcompat.app.AppCompatActivity
+import androidx.fragment.app.Fragment
+import androidx.fragment.app.commit
+
+class DetachAttachTabsActivity : AppCompatActivity(R.layout.activity_detach_attach_tabs) {
+
+  private val tags = arrayOf("tab_a", "tab_b")
+
+  override fun onCreate(savedInstanceState: Bundle?) {
+    super.onCreate(savedInstanceState)
+
+    findViewById<View>(R.id.btn_tab_a).setOnClickListener { showTab(0) }
+    findViewById<View>(R.id.btn_tab_b).setOnClickListener { showTab(1) }
+
+    if (savedInstanceState == null) {
+      val tabB = TabFragmentB()
+      supportFragmentManager.commit {
+        add(R.id.tab_container, TabFragmentA(), tags[0])
+        add(R.id.tab_container, tabB, tags[1])
+        detach(tabB)
+      }
+    }
+  }
+
+  private fun showTab(index: Int) {
+    supportFragmentManager.commit {
+      for (i in tags.indices) {
+        val frag = supportFragmentManager.findFragmentByTag(tags[i]) ?: continue
+        if (i == index) attach(frag) else detach(frag)
+      }
+    }
+  }
+}
+
+class TabFragmentA : Fragment(R.layout.fragment_tab) {
+  override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
+    view.findViewById<TextView>(R.id.tab_label).text = "Tab A"
+  }
+}
+
+class TabFragmentB : Fragment(R.layout.fragment_tab) {
+  override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
+    view.findViewById<TextView>(R.id.tab_label).text = "Tab B"
+  }
+}

sentry-samples/sentry-samples-android/src/main/java/io/sentry/samples/android/MainActivity.kt

@@ -794,6 +794,18 @@ fun IntegrationsScreen() {
         }
       }
     }
+    item {
+      SentryTraced("open_detach_attach_tabs") {
+        OutlinedButton(
+          onClick = {
+            activity.startActivity(Intent(activity, DetachAttachTabsActivity::class.java))
+          },
+          modifier = Modifier,
+        ) {
+          Text("Open Detach/Attach Tabs", maxLines = 2, overflow = TextOverflow.Ellipsis)
+        }
+      }
+    }
     item {
       SentryTraced("open_permissions_activity") {
         OutlinedButton(

sentry-samples/sentry-samples-android/src/main/res/layout/activity_detach_attach_tabs.xml

@@ -0,0 +1,31 @@
+<?xml version="1.0" encoding="utf-8"?>
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    android:orientation="vertical"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent">
+
+    <LinearLayout
+        android:orientation="horizontal"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:padding="8dp">
+
+        <Button
+            android:id="@+id/btn_tab_a"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:text="Tab A" />
+
+        <Button
+            android:id="@+id/btn_tab_b"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:text="Tab B" />
+    </LinearLayout>
+
+    <FrameLayout
+        android:id="@+id/tab_container"
+        android:layout_width="match_parent"
+        android:layout_height="0dp"
+        android:layout_weight="1" />
+</LinearLayout>

sentry-samples/sentry-samples-android/src/main/res/layout/fragment_tab.xml

@@ -0,0 +1,12 @@
+<?xml version="1.0" encoding="utf-8"?>
+<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent">
+
+    <TextView
+        android:id="@+id/tab_label"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:layout_gravity="center"
+        android:textSize="24sp" />
+</FrameLayout>