Move back to previous way of creating at least one test contact

briar-android/src/main/java/org/briarproject/briar/android/test/TestDataActivity.java

@@ -65,7 +65,7 @@ public class TestDataActivity extends BriarActivity {
 					@Override
 					public void onProgressChanged(SeekBar seekBar,
 							int progress, boolean fromUser) {
-						contactsTextView.setText(String.valueOf(progress));
+						contactsTextView.setText(String.valueOf(progress + 1));
 					}
 
 					@Override
@@ -151,7 +151,7 @@ public class TestDataActivity extends BriarActivity {
 	}
 
 	private void createTestData() {
-		testDataCreator.createTestData(contactsSeekBar.getProgress(),
+		testDataCreator.createTestData(contactsSeekBar.getProgress() + 1,
 				messagesSeekBar.getProgress(), blogPostsSeekBar.getProgress(),
 				forumsSeekBar.getProgress(), forumPostsSeekBar.getProgress());
 		Intent intent = new Intent(this, NavDrawerActivity.class);

briar-android/src/main/res/layout/activity_test_data.xml

@@ -27,7 +27,6 @@
 			android:layout_width="0dp"
 			android:layout_height="wrap_content"
 			android:max="50"
-			android:min="1"
 			android:progress="20"
 			app:layout_constraintEnd_toStartOf="@+id/textViewContactsSb"
 			app:layout_constraintStart_toStartOf="parent"

briar-core/src/main/java/org/briarproject/briar/test/TestDataCreatorImpl.java

@@ -116,6 +116,8 @@ public class TestDataCreatorImpl implements TestDataCreator {
 	@Override
 	public void createTestData(int numContacts, int numPrivateMsgs,
 			int numBlogPosts, int numForums, int numForumPosts) {
+		if (numContacts == 0) throw new IllegalArgumentException(
+				"Number of contacts must be >= 1");
 		ioExecutor.execute(() -> {
 			try {
 				createTestDataOnIoExecutor(numContacts, numPrivateMsgs,