diff --git a/tests/test_pilatus_csaxs.py b/tests/test_pilatus_csaxs.py
index 74f5322..2d70bfe 100644
--- a/tests/test_pilatus_csaxs.py
+++ b/tests/test_pilatus_csaxs.py
@@ -1,3 +1,4 @@
+import os
 import pytest
 from unittest import mock
 
@@ -358,6 +359,167 @@ def test_stop_file_writer(mock_det, requests_state, expected_exception, url):
             mock_send_requests_put.assert_called_once_with(url=url)
 
 
+@pytest.mark.parametrize(
+    "scaninfo, data_msgs, urls, requests_state, expected_exception",
+    [
+        (
+            {
+                "filepath_raw": "pilatus_2.h5",
+                "eacc": "e12345",
+                "scan_number": 1000,
+                "scan_directory": "S00000_00999",
+                "num_points": 500,
+                "frames_per_trigger": 1,
+                "headers": {"Content-Type": "application/json", "Accept": "application/json"},
+            },
+            [
+                {
+                    "source": [
+                        {
+                            "searchPath": "/",
+                            "searchPattern": "glob:*.cbf",
+                            "destinationPath": "/sls/X12SA/data/e12345/Data10/pilatus_2/S00000_00999",
+                        }
+                    ]
+                },
+                [
+                    "zmqWriter",
+                    "e12345",
+                    {
+                        "addr": "tcp://x12sa-pd-2:8888",
+                        "dst": ["file"],
+                        "numFrm": 500,
+                        "timeout": 2000,
+                        "ifType": "PULL",
+                        "user": "e12345",
+                    },
+                ],
+                [
+                    "zmqWriter",
+                    "e12345",
+                    {
+                        "frmCnt": 500,
+                        "timeout": 2000,
+                    },
+                ],
+            ],
+            [
+                "http://x12sa-pd-2:8080/stream/pilatus_2",
+                "http://xbl-daq-34:8091/pilatus_2/run",
+                "http://xbl-daq-34:8091/pilatus_2/wait",
+            ],
+            True,
+            False,
+        ),
+        (
+            {
+                "filepath_raw": "pilatus_2.h5",
+                "eacc": "e12345",
+                "scan_number": 1000,
+                "scan_directory": "S00000_00999",
+                "num_points": 500,
+                "frames_per_trigger": 1,
+                "headers": {"Content-Type": "application/json", "Accept": "application/json"},
+            },
+            [
+                {
+                    "source": [
+                        {
+                            "searchPath": "/",
+                            "searchPattern": "glob:*.cbf",
+                            "destinationPath": "/sls/X12SA/data/e12345/Data10/pilatus_2/S00000_00999",
+                        }
+                    ]
+                },
+                [
+                    "zmqWriter",
+                    "e12345",
+                    {
+                        "addr": "tcp://x12sa-pd-2:8888",
+                        "dst": ["file"],
+                        "numFrm": 500,
+                        "timeout": 2000,
+                        "ifType": "PULL",
+                        "user": "e12345",
+                    },
+                ],
+                [
+                    "zmqWriter",
+                    "e12345",
+                    {
+                        "frmCnt": 500,
+                        "timeout": 2000,
+                    },
+                ],
+            ],
+            [
+                "http://x12sa-pd-2:8080/stream/pilatus_2",
+                "http://xbl-daq-34:8091/pilatus_2/run",
+                "http://xbl-daq-34:8091/pilatus_2/wait",
+            ],
+            False,  # return of res.ok is False!
+            True,
+        ),
+    ],
+)
+def test_prep_file_writer(mock_det, scaninfo, data_msgs, urls, requests_state, expected_exception):
+    with mock.patch.object(
+        mock_det, "_close_file_writer"
+    ) as mock_close_file_writer, mock.patch.object(
+        mock_det, "_stop_file_writer"
+    ) as mock_stop_file_writer, mock.patch.object(
+        mock_det, "filewriter"
+    ) as mock_filewriter, mock.patch.object(
+        mock_det, "_create_directory"
+    ) as mock_create_directory, mock.patch.object(
+        mock_det, "_send_requests_put"
+    ) as mock_send_requests_put:
+        mock_det.scaninfo.scan_number = scaninfo["scan_number"]
+        mock_det.scaninfo.num_points = scaninfo["num_points"]
+        mock_det.scaninfo.frames_per_trigger = scaninfo["frames_per_trigger"]
+        mock_det.scaninfo.username = scaninfo["eacc"]
+        mock_filewriter.compile_full_filename.return_value = scaninfo["filepath_raw"]
+        mock_filewriter.get_scan_directory.return_value = scaninfo["scan_directory"]
+        instance = mock_send_requests_put.return_value
+        instance.ok = requests_state
+        instance.raise_for_status.side_effect = Exception
+
+        if expected_exception:
+            with pytest.raises(Exception):
+                mock_det._prep_file_writer()
+                mock_close_file_writer.assert_called_once()
+                mock_stop_file_writer.assert_called_once()
+                instance.raise_for_status.assert_called_once()
+        else:
+            mock_det._prep_file_writer()
+
+            mock_close_file_writer.assert_called_once()
+            mock_stop_file_writer.assert_called_once()
+
+            # Assert values set on detector
+            assert mock_det.cam.file_path.get() == "/dev/shm/zmq/"
+            assert (
+                mock_det.cam.file_name.get()
+                == f"{scaninfo['eacc']}_2_{scaninfo['scan_number']:05d}"
+            )
+            assert mock_det.cam.auto_increment.get() == 1
+            assert mock_det.cam.file_number.get() == 0
+            assert mock_det.cam.file_format.get() == 0
+            assert mock_det.cam.file_template.get() == "%s%s_%5.5d.cbf"
+            # Remove last / from destinationPath
+            mock_create_directory.assert_called_once_with(
+                os.path.join(data_msgs[0]["source"][0]["destinationPath"])
+            )
+            assert mock_send_requests_put.call_count == 3
+
+            calls = [
+                mock.call(url=url, data=data_msg, headers=scaninfo["headers"])
+                for url, data_msg in zip(urls, data_msgs)
+            ]
+            for call, mock_call in zip(calls, mock_send_requests_put.call_args_list):
+                assert call == mock_call
+
+
 # @pytest.mark.parametrize(
 #     "scaninfo, daq_status, expected_exception",
 #     [