Fix Android emulator CI test file permission error

Use internal cache directory instead of external cache directory for
Android instrumentation tests. On Android API 34, scoped storage
restrictions prevent writing to external storage even for app-specific
directories. Internal storage (cacheDir) requires no permissions and
works reliably on all API levels.

- Change externalCacheDir to cacheDir in TestFileUtils
- Remove unnecessary READ_EXTERNAL_STORAGE permission from manifest
- Remove GrantPermissionRule from all test files

Author: mergennachin

extension/android/executorch_android/src/androidTest/AndroidManifest.xml

@@ -1,6 +1,5 @@
 <?xml version="1.0" encoding="utf-8"?>
 <manifest xmlns:android="http://schemas.android.com/apk/res/android">
-    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
     <application>
     </application>
     <instrumentation

extension/android/executorch_android/src/androidTest/java/org/pytorch/executorch/LlmModuleInstrumentationTest.kt

@@ -7,9 +7,7 @@
  */
 package org.pytorch.executorch
 
-import android.Manifest
 import androidx.test.ext.junit.runners.AndroidJUnit4
-import androidx.test.rule.GrantPermissionRule
 import java.io.File
 import java.io.IOException
 import java.net.URISyntaxException
@@ -19,7 +17,6 @@ import org.json.JSONObject
 import org.junit.Assert.assertEquals
 import org.junit.Assert.assertTrue
 import org.junit.Before
-import org.junit.Rule
 import org.junit.Test
 import org.junit.runner.RunWith
 import org.pytorch.executorch.TestFileUtils.getTestFilePath
@@ -51,10 +48,6 @@ class LlmModuleInstrumentationTest : LlmCallback {
         LlmModule(getTestFilePath(TEST_FILE_NAME), getTestFilePath(TOKENIZER_FILE_NAME), 0.0f)
   }
 
-  @get:Rule
-  var runtimePermissionRule: GrantPermissionRule =
-      GrantPermissionRule.grant(Manifest.permission.READ_EXTERNAL_STORAGE)
-
   @Test
   @Throws(IOException::class, URISyntaxException::class)
   fun testGenerate() {

extension/android/executorch_android/src/androidTest/java/org/pytorch/executorch/ModuleE2ETest.kt

@@ -7,18 +7,15 @@
  */
 package org.pytorch.executorch
 
-import android.Manifest
 import android.graphics.Bitmap
 import android.graphics.BitmapFactory
 import androidx.test.ext.junit.runners.AndroidJUnit4
-import androidx.test.rule.GrantPermissionRule
 import java.io.File
 import java.io.IOException
 import java.net.URISyntaxException
 import org.apache.commons.io.FileUtils
 import org.junit.Assert
 import org.junit.Assert.assertArrayEquals
-import org.junit.Rule
 import org.junit.Test
 import org.junit.runner.RunWith
 import org.pytorch.executorch.TensorImageUtils.bitmapToFloat32Tensor
@@ -27,9 +24,6 @@ import org.pytorch.executorch.TestFileUtils.getTestFilePath
 /** Unit tests for [Module]. */
 @RunWith(AndroidJUnit4::class)
 class ModuleE2ETest {
-  @get:Rule
-  var runtimePermissionRule: GrantPermissionRule =
-      GrantPermissionRule.grant(Manifest.permission.READ_EXTERNAL_STORAGE)
 
   @Throws(IOException::class, URISyntaxException::class)
   fun testClassification(filePath: String) {

extension/android/executorch_android/src/androidTest/java/org/pytorch/executorch/ModuleInstrumentationTest.kt

@@ -7,9 +7,7 @@
  */
 package org.pytorch.executorch
 
-import android.Manifest
 import androidx.test.ext.junit.runners.AndroidJUnit4
-import androidx.test.rule.GrantPermissionRule
 import java.io.File
 import java.io.IOException
 import java.net.URISyntaxException
@@ -20,7 +18,6 @@ import org.apache.commons.io.FileUtils
 import org.junit.Assert
 import org.junit.Before
 import org.junit.Ignore
-import org.junit.Rule
 import org.junit.Test
 import org.junit.runner.RunWith
 import org.pytorch.executorch.TestFileUtils.getTestFilePath
@@ -43,10 +40,6 @@ class ModuleInstrumentationTest {
     inputStream.close()
   }
 
-  @get:Rule
-  var runtimePermissionRule: GrantPermissionRule =
-      GrantPermissionRule.grant(Manifest.permission.READ_EXTERNAL_STORAGE)
-
   @Ignore(
       "The forward has failure that needs to be fixed before enabling this test: [Executorch Error 0x12] Invalid argument: Execution failed for method: forward "
   )

extension/android/executorch_android/src/androidTest/java/org/pytorch/executorch/TestFileUtils.kt

@@ -6,7 +6,7 @@ import androidx.test.InstrumentationRegistry
 object TestFileUtils {
 
   fun getTestFilePath(fileName: String): String {
-    return InstrumentationRegistry.getInstrumentation().targetContext.externalCacheDir.toString() +
+    return InstrumentationRegistry.getInstrumentation().targetContext.cacheDir.toString() +
         fileName
   }
 }

extension/android/executorch_android/src/androidTest/java/org/pytorch/executorch/training/TrainingModuleE2ETest.kt

@@ -8,18 +8,15 @@
 
 package org.pytorch.executorch.training
 
-import android.Manifest
 import android.util.Log
 import androidx.test.ext.junit.runners.AndroidJUnit4
-import androidx.test.rule.GrantPermissionRule
 import java.io.File
 import java.io.IOException
 import java.net.URISyntaxException
 import kotlin.random.Random
 import kotlin.test.assertContains
 import org.apache.commons.io.FileUtils
 import org.junit.Assert
-import org.junit.Rule
 import org.junit.Test
 import org.junit.runner.RunWith
 import org.pytorch.executorch.EValue
@@ -29,9 +26,6 @@ import org.pytorch.executorch.TestFileUtils
 /** Unit tests for [TrainingModule]. */
 @RunWith(AndroidJUnit4::class)
 class TrainingModuleE2ETest {
-  @get:Rule
-  var runtimePermissionRule: GrantPermissionRule =
-      GrantPermissionRule.grant(Manifest.permission.READ_EXTERNAL_STORAGE)
 
   @Test
   @Throws(IOException::class, URISyntaxException::class)