fix emulator tests on android-10, closes #769

We have to work harder to get writeable dirs in the android-10 emulator.

.gitlab-ci.yml

@@ -46,7 +46,6 @@ connected10:
     # this file changes every time but should not be cached
     - rm -f $GRADLE_USER_HOME/caches/modules-2/modules-2.lock
     - exit $EXITVALUE
-  allow_failure: true  # remove once install segfaults are gone
 
 connected24:
   variables:

app/src/androidTest/java/org/fdroid/fdroid/CleanCacheServiceTest.java

@@ -1,8 +1,11 @@
 package org.fdroid.fdroid;
 
+import android.app.Instrumentation;
+import android.support.test.InstrumentationRegistry;
 import android.support.test.runner.AndroidJUnit4;
 
 import org.apache.commons.io.FileUtils;
+import org.fdroid.fdroid.compat.FileCompatTest;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 
@@ -19,7 +22,8 @@ public class CleanCacheServiceTest {
 
     @Test
     public void testClearOldFiles() throws IOException, InterruptedException {
-        File tempDir = new File(System.getProperty("java.io.tmpdir"));
+        Instrumentation instrumentation = InstrumentationRegistry.getInstrumentation();
+        File tempDir = FileCompatTest.getWriteableDir(instrumentation);
         assertTrue(tempDir.isDirectory());
         assertTrue(tempDir.canWrite());
 

app/src/androidTest/java/org/fdroid/fdroid/compat/FileCompatTest.java

@@ -80,7 +80,7 @@ public class FileCompatTest {
      * Prefer internal over external storage, because external tends to be FAT filesystems,
      * which don't support symlinks (which we test using this method).
      */
-    private static File getWriteableDir(Instrumentation instrumentation) {
+    public static File getWriteableDir(Instrumentation instrumentation) {
         Context context = instrumentation.getContext();
         Context targetContext = instrumentation.getTargetContext();
 

app/src/androidTest/java/org/fdroid/fdroid/installer/ApkVerifierTest.java

@@ -25,15 +25,13 @@ import android.support.test.InstrumentationRegistry;
 import android.support.test.runner.AndroidJUnit4;
 
 import org.fdroid.fdroid.AssetUtils;
+import org.fdroid.fdroid.compat.FileCompatTest;
 import org.fdroid.fdroid.data.Apk;
 import org.junit.Before;
-import org.junit.Rule;
 import org.junit.Test;
-import org.junit.rules.TemporaryFolder;
 import org.junit.runner.RunWith;
 
 import java.io.File;
-import java.io.IOException;
 
 import static org.junit.Assert.assertTrue;
 import static org.junit.Assert.fail;
@@ -59,18 +57,12 @@ public class ApkVerifierTest {
     File sdk14Apk;
     File minMaxApk;
 
-    @Rule
-    public TemporaryFolder tempFolder = new TemporaryFolder();
-
     @Before
     public void setUp() {
         instrumentation = InstrumentationRegistry.getInstrumentation();
-        File dir = null;
+        File dir = FileCompatTest.getWriteableDir(instrumentation);
-        try {
+        assertTrue(dir.isDirectory());
-            dir = tempFolder.newFolder("apks");
+        assertTrue(dir.canWrite());
-        } catch (IOException e) {
-            fail(e.getMessage());
-        }
         sdk14Apk = AssetUtils.copyAssetToDir(instrumentation.getContext(),
                 "org.fdroid.permissions.sdk14.apk",
                 dir