diff --git a/.gitmodules b/.gitmodules
deleted file mode 100644
index 0f685d2..0000000
--- a/.gitmodules
+++ /dev/null
@@ -1,6 +0,0 @@
-[submodule "tests/storage/servers/owncloud"]
-	path = tests/storage/servers/owncloud
-	url = https://github.com/vdirsyncer/owncloud-testserver
-[submodule "tests/storage/servers/nextcloud"]
-	path = tests/storage/servers/nextcloud
-	url = https://github.com/vdirsyncer/nextcloud-testserver
diff --git a/Makefile b/Makefile
index 6f7b7a1..4ca8f2b 100644
--- a/Makefile
+++ b/Makefile
@@ -63,9 +63,6 @@ all:
 install-servers:
 	set -ex; \
 	for server in $(DAV_SERVER); do \
-		if [ ! "$$(ls $(TESTSERVER_BASE)$$server/)" ]; then \
-			git submodule update --init -- "$(TESTSERVER_BASE)$$server"; \
-		fi; \
 		(cd $(TESTSERVER_BASE)$$server && sh install.sh); \
 	done
 
diff --git a/docker/radicale/Dockerfile b/docker/radicale/Dockerfile
deleted file mode 100644
index 462c5e2..0000000
--- a/docker/radicale/Dockerfile
+++ /dev/null
@@ -1,5 +0,0 @@
-FROM python:3.8
-
-RUN pip install radicale
-
-CMD radicale --storage-filesystem-folder /tmp/dav -H 0.0.0.0:8001 -D
diff --git a/docker/xandikos/Dockerfile b/docker/xandikos/Dockerfile
deleted file mode 100644
index 464450c..0000000
--- a/docker/xandikos/Dockerfile
+++ /dev/null
@@ -1,13 +0,0 @@
-# Original file copyright 2017 Jelmer Vernooij
-
-FROM ubuntu:bionic
-RUN apt-get update && apt-get -y install xandikos locales
-EXPOSE 8000
-
-RUN locale-gen en_US.UTF-8
-ENV PYTHONIOENCODING=utf-8
-ENV LANG en_US.UTF-8
-ENV LANGUAGE en_US:en
-ENV LC_ALL en_US.UTF-8
-
-CMD xandikos -d /tmp/dav -l 0.0.0.0 -p 8000 --autocreate
diff --git a/tests/storage/servers/nextcloud b/tests/storage/servers/nextcloud
deleted file mode 160000
index a27144d..0000000
--- a/tests/storage/servers/nextcloud
+++ /dev/null
@@ -1 +0,0 @@
-Subproject commit a27144ddcf39a3283179a4f7ce1ab22b2e810205
diff --git a/tests/storage/servers/owncloud b/tests/storage/servers/owncloud
deleted file mode 160000
index bb4fcc6..0000000
--- a/tests/storage/servers/owncloud
+++ /dev/null
@@ -1 +0,0 @@
-Subproject commit bb4fcc6f524467d58c95f1dcec8470fdfcd65adf
diff --git a/tests/storage/servers/radicale/install.sh b/tests/storage/servers/radicale/install.sh
index 690c9f3..fdeaff9 100644
--- a/tests/storage/servers/radicale/install.sh
+++ b/tests/storage/servers/radicale/install.sh
@@ -1,6 +1,3 @@
 #!/bin/sh
 
-cd $(git rev-parse --show-toplevel)
-
-docker build -t radicale docker/radicale
-docker run -d -p 8001:8001 radicale
+docker run -d -p 8001:8001 whynothugo/vdirsyncer-devkit-radicale
diff --git a/tests/storage/servers/xandikos/install.sh b/tests/storage/servers/xandikos/install.sh
index ff322b9..aa7b089 100644
--- a/tests/storage/servers/xandikos/install.sh
+++ b/tests/storage/servers/xandikos/install.sh
@@ -1,6 +1,3 @@
 #!/bin/sh
 
-cd $(git rev-parse --show-toplevel)
-
-docker build -t xandikos docker/xandikos
-docker run -d -p 8000:8000 xandikos
+docker run -d -p 8000:8000 whynothugo/vdirsyncer-devkit-xandikos
diff --git a/tests/storage/test_filesystem.py b/tests/storage/test_filesystem.py
index f85c1f3..d14999c 100644
--- a/tests/storage/test_filesystem.py
+++ b/tests/storage/test_filesystem.py
@@ -46,38 +46,40 @@ class TestFilesystemStorage(StorageTests):
 
     def test_ignore_tmp_files(self, tmpdir):
         """Test that files with .tmp suffix beside .ics files are ignored."""
-        s = self.storage_class(str(tmpdir), '.ics')
-        s.upload(Item('UID:xyzxyz'))
-        item_file, = tmpdir.listdir()
-        item_file.copy(item_file.new(ext='tmp'))
+        s = self.storage_class(str(tmpdir), ".ics")
+        s.upload(Item("UID:xyzxyz"))
+        (item_file,) = tmpdir.listdir()
+        item_file.copy(item_file.new(ext="tmp"))
         assert len(tmpdir.listdir()) == 2
         assert len(list(s.list())) == 1
 
     def test_ignore_tmp_files_empty_fileext(self, tmpdir):
         """Test that files with .tmp suffix are ignored with empty fileext."""
-        s = self.storage_class(str(tmpdir), '')
-        s.upload(Item('UID:xyzxyz'))
-        item_file, = tmpdir.listdir()
-        item_file.copy(item_file.new(ext='tmp'))
+        s = self.storage_class(str(tmpdir), "")
+        s.upload(Item("UID:xyzxyz"))
+        (item_file,) = tmpdir.listdir()
+        item_file.copy(item_file.new(ext="tmp"))
         assert len(tmpdir.listdir()) == 2
         # assert False, tmpdir.listdir() # enable to see the created filename
         assert len(list(s.list())) == 1
 
     def test_ignore_files_typical_backup(self, tmpdir):
         """Test file-name ignorance with typical backup ending ~."""
-        ignorext = "~" # without dot
-        s = self.storage_class(str(tmpdir), '', fileignoreext="~")
-        s.upload(Item('UID:xyzxyz'))
-        item_file, = tmpdir.listdir()
-        item_file.copy(item_file.new(basename=item_file.basename+'~'))
+        ignorext = "~"  # without dot
+
+        storage = self.storage_class(str(tmpdir), "", fileignoreext=ignorext)
+        storage.upload(Item("UID:xyzxyz"))
+        (item_file,) = tmpdir.listdir()
+        item_file.copy(item_file.new(basename=item_file.basename + ignorext))
+
         assert len(tmpdir.listdir()) == 2
-        #assert False, tmpdir.listdir() # enable to see the created filename
-        assert len(list(s.list())) == 1
+        assert len(list(storage.list())) == 1
 
     def test_too_long_uid(self, tmpdir):
-        s = self.storage_class(str(tmpdir), ".txt")
+        storage = self.storage_class(str(tmpdir), ".txt")
         item = Item("UID:" + "hue" * 600)
-        href, etag = s.upload(item)
+
+        href, etag = storage.upload(item)
         assert item.uid not in href
 
     def test_post_hook_inactive(self, tmpdir, monkeypatch):