diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 5fab39edd484..510fd5e94885 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -14,7 +14,7 @@
 1. [Contributing to Source Code](#contributing-to-source-code)
     1. [Developing process](#developing-process)
         1. [Branching model](#branching-model)
-        1. [Android Studio formatter setup](#android-studio-formatter-setup)
+        1. [Formatter setup](#formatter-setup)
         1. [Build variants](#build-variants)
         1. [Git hooks](#git-hooks)
     1. [Contribution process](#contribution-process)
@@ -107,12 +107,22 @@ We are all about quality while not sacrificing speed so we use a very pragmatic
 * Hot fixes not relevant for an upcoming feature release but the latest release can target the bug fix branch directly
 
 
-### Android Studio formatter setup
+### Formatter setup
 Our formatter setup is rather simple:
 * Standard Android Studio
-* Line length 120 characters (Settings->Editor->Code Style->Right margin(columns): 120)
+* Line length 120 characters (Settings->Editor->Code Style->Right margin(columns): 120; also set by EditorConfig
 * Auto optimize imports (Settings->Editor->Auto Import->Optimize imports on the fly)
 
+You can fix Check / check (spotlessKotlinCheck) via following commands:
+
+```bash
+./gradlew spotlessApply
+./gradlew detekt
+./gradlew spotlessCheck
+./gradlew spotlessKotlinCheck
+```
+
+See section [Git hooks](#git-hooks) to have these run automatically with your commits.
 
 ### Build variants
 There are three build variants
@@ -122,7 +132,7 @@ There are three build variants
 
 ### Git hooks
 We provide git hooks to make development process easier for both the developer and the reviewers.
-To install them, just run:
+They are stored in [/scripts/hooks](/scripts/hooks) and can be installed with:
 
 ```bash
 ./gradlew installGitHooks
@@ -214,21 +224,37 @@ Source code of app:
 - small, isolated tests, with no need of Android SDK
 - code coverage can be directly shown via right click on test and select "Run Test with Coverage"
 
+```
+./gradlew jacocoTestGplayDebugUnitTest
+```bash
+
 #### Instrumented tests
 - tests to see larger code working in correct way
 - tests that require parts of Android SDK
-- best to avoid server communication, see https://github.com/nextcloud/android/pull/3624
 
 - run all tests ```./gradlew createGplayDebugCoverageReport -Pcoverage=true```
 - run selective test class: ```./gradlew createGplayDebugCoverageReport -Pcoverage=true
-  -Pandroid.testInstrumentationRunnerArguments.class=com.owncloud.android.datamodel.FileDataStorageManagerTest```
+  -Pandroid.testInstrumentationRunnerArguments.class=com.owncloud.android.datamodel.FileDataStorageManagerContentProviderClientIT```
 - run multiple test classes:
   -   separate by ","
-  - ```./gradlew createGplayDebugCoverageReport -Pcoverage=true -Pandroid.testInstrumentationRunnerArguments.class=com.owncloud.android.datamodel.FileDataStorageManagerTest,com.nextcloud.client.FileDisplayActivityIT```
+  - ```./gradlew createGplayDebugCoverageReport -Pcoverage=true -Pandroid.testInstrumentationRunnerArguments.class=com.owncloud.android.datamodel.FileDataStorageManagerContentProviderClientIT,com.nextcloud.client.FileDisplayActivityIT```
 - run one test in class: ```./gradlew createGplayDebugCoverageReport -Pcoverage=true
-  -Pandroid.testInstrumentationRunnerArguments.class=com.owncloud.android.datamodel.FileDataStorageManagerTest#saveNewFile```
+  -Pandroid.testInstrumentationRunnerArguments.class=com.owncloud.android.datamodel.FileDataStorageManagerContentProviderClientIT#saveFile```
 - JaCoCo results are shown as html: firefox ./build/reports/coverage/gplay/debug/index.html
 
+#### Instrumented tests with server communication
+It is best to avoid server communication, see https://github.com/nextcloud/android/pull/3624.
+But if a test requires a server, this is how it is done:
+- Have a Nextcloud service reachable by your test device. This can be an existing server in the internet or a locally deployed one
+as per the [server developer documentation](https://docs.nextcloud.com/server/latest/developer_manual/getting_started/devenv.html)
+- Create a separate(!) test user on that server, otherwise the tests will infer with productive data.
+- In `gradle.properties`, enter the URL, user name and password via the `NC_TEST_SERVER_...` attributes.
+  If you want to prevent an accidental commit of those, you can also store them in `~/.gradle/gradle.properties`.
+- Your test class should inherit from `AbstractOnServerIT`, e.g.: `public class DownloadIT extends AbstractOnServerIT { ...`
+  Note that this will automatically delete all files after each test run, so you absolutely NEED a separate test user as mentioned above.
+- All preconditions of your test regarding server data, e.g. existing files, need to be established by your test itself.
+  As a reference, see how `DownloadIT` first uploads the files it later tests the download with.
+- Clean up these preconditions again, also in the failure case, using one or multiple `@After` methods in your test class.
 
 #### UI tests
 We use [shot](https://github.com/Karumi/Shot) for taking screenshots and compare them 
diff --git a/README.md b/README.md
index bd99dd07fe89..1a23a124eb06 100644
--- a/README.md
+++ b/README.md
@@ -48,6 +48,7 @@ If you want to [contribute](https://nextcloud.com/contribute/) to the Nextcloud
 *   reporting problems / suggesting enhancements by [opening new issues](https://github.com/nextcloud/android/issues/new/choose)
 *   implementing proposed bug fixes and enhancement ideas by submitting PRs (associated with a corresponding issue preferably)
 *   reviewing [pull requests](https://github.com/nextcloud/android/pulls) and providing feedback on code, implementation, and functionality
+*   Add [automated tests](CONTRIBUTING.md#testing) for existing functionality
 *   installing and testing [pull request builds](https://github.com/nextcloud/android/pulls), [daily/dev builds](https://github.com/nextcloud/android#development-version-hammer), or [RCs/release candidate builds](https://github.com/nextcloud/android/releases) 
 *   enhancing Admin, User, or Developer [documentation](https://github.com/nextcloud/documentation/)
 *   hitting hard on the latest stable release by testing fundamental features and evaluating the user experience
diff --git a/app/src/androidTest/java/com/nextcloud/test/GrantStoragePermissionRule.kt b/app/src/androidTest/java/com/nextcloud/test/GrantStoragePermissionRule.kt
index b310a897fa42..3bade62247c4 100644
--- a/app/src/androidTest/java/com/nextcloud/test/GrantStoragePermissionRule.kt
+++ b/app/src/androidTest/java/com/nextcloud/test/GrantStoragePermissionRule.kt
@@ -15,6 +15,10 @@ import org.junit.rules.TestRule
 import org.junit.runner.Description
 import org.junit.runners.model.Statement
 
+/**
+ * Rule to automatically enable the test to write to the external storage.
+ * Depending on the SDK version, different approaches might be necessary to achieve the full access.
+ */
 class GrantStoragePermissionRule private constructor() {
 
     companion object {
@@ -30,6 +34,7 @@ class GrantStoragePermissionRule private constructor() {
     private class GrantManageExternalStoragePermissionRule : TestRule {
         override fun apply(base: Statement, description: Description): Statement = object : Statement() {
             override fun evaluate() {
+                // Refer to https://developer.android.com/training/data-storage/manage-all-files#enable-manage-external-storage-for-testing
                 InstrumentationRegistry.getInstrumentation().uiAutomation.executeShellCommand(
                     "appops set --uid ${InstrumentationRegistry.getInstrumentation().targetContext.packageName} " +
                         "MANAGE_EXTERNAL_STORAGE allow"
diff --git a/app/src/androidTest/java/com/owncloud/android/AbstractIT.java b/app/src/androidTest/java/com/owncloud/android/AbstractIT.java
index 5ea27541062f..0c213f846757 100644
--- a/app/src/androidTest/java/com/owncloud/android/AbstractIT.java
+++ b/app/src/androidTest/java/com/owncloud/android/AbstractIT.java
@@ -6,6 +6,7 @@
  */
 package com.owncloud.android;
 
+import android.Manifest;
 import android.accounts.Account;
 import android.accounts.AccountManager;
 import android.accounts.AuthenticatorException;
@@ -78,6 +79,7 @@
 import androidx.test.espresso.contrib.DrawerActions;
 import androidx.test.espresso.intent.rule.IntentsTestRule;
 import androidx.test.platform.app.InstrumentationRegistry;
+import androidx.test.rule.GrantPermissionRule;
 import androidx.test.runner.lifecycle.ActivityLifecycleMonitorRegistry;
 import androidx.test.runner.lifecycle.Stage;
 
@@ -93,7 +95,10 @@
  */
 public abstract class AbstractIT {
     @Rule
-    public final TestRule permissionRule = GrantStoragePermissionRule.grant();
+    public final TestRule storagePermissionRule = GrantStoragePermissionRule.grant();
+
+    @Rule
+    public GrantPermissionRule notificationsPermissionRule = GrantPermissionRule.grant(Manifest.permission.POST_NOTIFICATIONS);
 
     protected static OwnCloudClient client;
     protected static NextcloudClient nextcloudClient;
@@ -118,7 +123,7 @@ public static void beforeAll() {
             AccountManager platformAccountManager = AccountManager.get(targetContext);
 
             for (Account account : platformAccountManager.getAccounts()) {
-                if (account.type.equalsIgnoreCase("nextcloud")) {
+                if (account.type.equalsIgnoreCase(MainApp.getAccountType(targetContext))) {
                     platformAccountManager.removeAccountExplicitly(account);
                 }
             }
diff --git a/app/src/androidTest/java/com/owncloud/android/AbstractOnServerIT.java b/app/src/androidTest/java/com/owncloud/android/AbstractOnServerIT.java
index aef7eee1110c..2b1428ed551a 100644
--- a/app/src/androidTest/java/com/owncloud/android/AbstractOnServerIT.java
+++ b/app/src/androidTest/java/com/owncloud/android/AbstractOnServerIT.java
@@ -36,6 +36,7 @@
 import com.owncloud.android.lib.resources.files.model.RemoteFile;
 import com.owncloud.android.operations.RefreshFolderOperation;
 import com.owncloud.android.operations.UploadFileOperation;
+import com.owncloud.android.utils.MimeType;
 
 import org.apache.commons.httpclient.HttpStatus;
 import org.apache.commons.httpclient.methods.GetMethod;
@@ -54,7 +55,16 @@
 import static org.junit.Assert.assertTrue;
 
 /**
- * Common base for all integration tests.
+ * Common base for all integration tests requiring a server connection.
+ * ATTENTION: Deletes ALL files of the test user on the server after each test run.
+ * So you MUST use a dedicated test user.
+ *
+ * Uses server, user and password given as `testInstrumentationRunnerArgument`
+ * - TEST_SERVER_URL
+ * - TEST_SERVER_USERNAME
+ * - TEST_SERVER_PASSWORD
+ * These are supplied via build.gradle, which takes them from gradle.properties.
+ * So look in the latter file to set to your own server & test user.
  */
 public abstract class AbstractOnServerIT extends AbstractIT {
     @BeforeClass
@@ -121,6 +131,11 @@ public void after() {
         super.after();
     }
 
+    private static boolean isFolder(RemoteFile file) {
+        // TODO: should probably move to RemoteFile class
+        return MimeType.DIRECTORY.equals(file.getMimeType()) || MimeType.WEBDAV_FOLDER.equals(file.getMimeType());
+    }
+
     public static void deleteAllFilesOnServer() {
         RemoteOperationResult result = new ReadFolderRemoteOperation("/").execute(client);
         assertTrue(result.getLogMessage(), result.isSuccess());
@@ -138,6 +153,13 @@ public static void deleteAllFilesOnServer() {
                         .execute(client)
                         .isSuccess();
 
+                    if (!operationResult && isFolder(remoteFile)) {
+                        // Deleting encrypted folder is not possible due to bug
+                        // https://github.com/nextcloud/end_to_end_encryption/issues/421
+                        // Toggling encryption also fails, when the folder is not empty. So we ignore this folder
+                        continue;
+                    }
+
                     assertTrue(operationResult);
                 }
 
diff --git a/app/src/androidTest/java/com/owncloud/android/DownloadIT.java b/app/src/androidTest/java/com/owncloud/android/DownloadIT.java
index 610469f4d3fa..f8fd99517f1c 100644
--- a/app/src/androidTest/java/com/owncloud/android/DownloadIT.java
+++ b/app/src/androidTest/java/com/owncloud/android/DownloadIT.java
@@ -29,7 +29,7 @@
 import static org.junit.Assert.assertTrue;
 
 /**
- * Tests related to file uploads.
+ * Tests related to file downloads.
  */
 public class DownloadIT extends AbstractOnServerIT {
     private static final String FOLDER = "/testUpload/";
@@ -98,10 +98,10 @@ private void verifyDownload(OCFile file1, OCFile file2) {
         assertTrue(new File(file2.getStoragePath()).exists());
 
         // test against hardcoded path to make sure that it is correct
-        assertEquals("/storage/emulated/0/Android/media/com.nextcloud.client/nextcloud/" +
+        assertEquals("/storage/emulated/0/Android/media/"+targetContext.getPackageName()+"/nextcloud/" +
                          Uri.encode(account.name, "@") + "/testUpload/nonEmpty.txt",
                      file1.getStoragePath());
-        assertEquals("/storage/emulated/0/Android/media/com.nextcloud.client/nextcloud/" +
+        assertEquals("/storage/emulated/0/Android/media/"+targetContext.getPackageName()+"/nextcloud/" +
                          Uri.encode(account.name, "@") + "/testUpload/nonEmpty2.txt",
                      file2.getStoragePath());
     }