fix(gestures): Use peekDecorView to not force view hierarchy construction

CHANGELOG.md

@@ -32,6 +32,7 @@
 
 - Remove `AndroidRuntimeManager` StrictMode relaxation to prevent ANRs during SDK init ([#5127](https://github.com/getsentry/sentry-java/pull/5127))
 - Fix crash when unregistering `SystemEventsBroadcastReceiver` with try-catch block. ([#5106](https://github.com/getsentry/sentry-java/pull/5106))
+- Use `peekDecorView` instead of `getDecorView` in `SentryGestureListener` to avoid forcing view hierarchy construction ([#5134](https://github.com/getsentry/sentry-java/pull/5134))
 - Log an actionable error message when Relay returns HTTP 413 (Content Too Large) ([#5115](https://github.com/getsentry/sentry-java/pull/5115))
   - Also switch the client report discard reason for all HTTP 4xx/5xx errors (except 429) from `network_error` to `send_error`
 - Trim DSN string before parsing to avoid `URISyntaxException` caused by trailing whitespace ([#5113](https://github.com/getsentry/sentry-java/pull/5113))

sentry-android-core/src/main/java/io/sentry/android/core/internal/gestures/SentryGestureListener.java

@@ -347,7 +347,7 @@ void applyScope(final @NotNull IScope scope, final @NotNull ITransaction transac
       return null;
     }
 
-    final View decorView = window.getDecorView();
+    final View decorView = window.peekDecorView();
     if (decorView == null) {
       options
           .getLogger()

sentry-android-core/src/test/java/io/sentry/android/core/internal/gestures/SentryGestureListenerPeekDecorViewTest.kt

@@ -0,0 +1,48 @@
+package io.sentry.android.core.internal.gestures
+
+import android.app.Activity
+import android.view.MotionEvent
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import io.sentry.Breadcrumb
+import io.sentry.IScopes
+import io.sentry.android.core.SentryAndroidOptions
+import io.sentry.util.LazyEvaluator
+import kotlin.test.Test
+import kotlin.test.assertNull
+import org.junit.runner.RunWith
+import org.mockito.kotlin.any
+import org.mockito.kotlin.anyOrNull
+import org.mockito.kotlin.mock
+import org.mockito.kotlin.never
+import org.mockito.kotlin.verify
+import org.robolectric.Robolectric.buildActivity
+
+@RunWith(AndroidJUnit4::class)
+class SentryGestureListenerPeekDecorViewTest {
+
+  @Test
+  fun `does not force decor view creation when peekDecorView returns null`() {
+    // A plain Activity that never calls setContentView — peekDecorView() should return null
+    val activity = buildActivity(Activity::class.java).create().get()
+
+    // Sanity check: decor view has not been created yet
+    assertNull(activity.window.peekDecorView())
+
+    val scopes = mock<IScopes>()
+    val options =
+      SentryAndroidOptions().apply {
+        isEnableUserInteractionBreadcrumbs = true
+        gestureTargetLocators = listOf(AndroidViewGestureTargetLocator(LazyEvaluator { true }))
+        dsn = "https://key@sentry.io/proj"
+      }
+
+    val sut = SentryGestureListener(activity, scopes, options)
+    sut.onSingleTapUp(mock<MotionEvent>())
+
+    // The key assertion: peekDecorView is still null — we did not force view hierarchy creation
+    assertNull(activity.window.peekDecorView())
+
+    // And no breadcrumb was captured
+    verify(scopes, never()).addBreadcrumb(any<Breadcrumb>(), anyOrNull())
+  }
+}

sentry-android-core/src/test/java/io/sentry/android/core/internal/gestures/ViewHelpers.kt

@@ -22,7 +22,7 @@ internal inline fun <reified T : View> Window.mockDecorView(
   finalize: (T) -> Unit = {},
 ): T {
   val view = mockView(id, event, touchWithinBounds, clickable, visible, context, finalize)
-  whenever(decorView).doReturn(view)
+  whenever(peekDecorView()).doReturn(view)
   return view
 }