Fix --report-to in tests

tests/test_xfel_calibrate/conftest.py

@@ -215,7 +215,9 @@ class CalibrateCall:
         self.in_folder = in_folder
         self.out_folder = out_folder
 
-        self.args = [command, detector, cal_type, '--report-to', str(reports_dir)]
+        self.args = [
+            command, detector, cal_type, '--report-to', str(reports_dir / 'test.pdf')
+        ]
         if in_folder:
             self.args.extend(["--in-folder", str(self.in_folder)])
         if out_folder: