Dump threads for troubleshooting when catalyst test timeout

Bug: 370394101
Flag: EXEMPT test only
Test: Manual
Change-Id: Ib361e621d6b34db987205c14343d6f27231072bb
diff --git a/packages/SettingsLib/Preference/testutils/com/android/settingslib/preference/CatalystScreenTestCase.kt b/packages/SettingsLib/Preference/testutils/com/android/settingslib/preference/CatalystScreenTestCase.kt
index e27838c..1412c84 100644
--- a/packages/SettingsLib/Preference/testutils/com/android/settingslib/preference/CatalystScreenTestCase.kt
+++ b/packages/SettingsLib/Preference/testutils/com/android/settingslib/preference/CatalystScreenTestCase.kt
@@ -27,6 +27,7 @@
 import androidx.test.core.app.ApplicationProvider
 import androidx.test.ext.junit.runners.AndroidJUnit4
 import com.google.common.truth.Truth.assertThat
+import java.util.concurrent.atomic.AtomicBoolean
 import org.junit.Rule
 import org.junit.Test
 import org.junit.runner.RunWith
@@ -53,7 +54,7 @@
         enableCatalystScreen()
         assertThat(preferenceScreenCreator.isFlagEnabled(context)).isTrue()
         val catalystScreen = dumpPreferenceScreen()
-        Log.i("Catalyst", catalystScreen)
+        Log.i(TAG, catalystScreen)
 
         disableCatalystScreen()
         assertThat(preferenceScreenCreator.isFlagEnabled(context)).isFalse()
@@ -83,11 +84,26 @@
     }
 
     private fun dumpPreferenceScreen(): String {
+        // Dump threads for troubleshooting when the test thread is stuck.
+        // Latest junit Timeout rule supports similar feature but it is not yet available on AOSP.
+        val taskFinished = AtomicBoolean()
+        Thread {
+                Thread.sleep(20000)
+                if (!taskFinished.get()) dumpThreads()
+            }
+            .apply {
+                isDaemon = true
+                start()
+            }
+
         @Suppress("UNCHECKED_CAST")
         val clazz = preferenceScreenCreator.fragmentClass() as Class<PreferenceFragmentCompat>
         val builder = StringBuilder()
         FragmentScenario.launch(clazz).use {
-            it.onFragment { fragment -> fragment.preferenceScreen.toString(builder) }
+            it.onFragment { fragment ->
+                taskFinished.set(true)
+                fragment.preferenceScreen.toString(builder)
+            }
         }
         return builder.toString()
     }
@@ -120,4 +136,16 @@
         }
         builder.append(indent).append("}\n")
     }
+
+    companion object {
+        const val TAG = "CatalystScreenTestCase"
+
+        fun dumpThreads() {
+            for ((thread, stack) in Thread.getAllStackTraces()) {
+                Log.i(TAG, "$thread")
+                for (frame in stack) Log.i(TAG, "  $frame")
+                Log.i(TAG, "")
+            }
+        }
+    }
 }