diff --git a/src/testdir/test_channel.vim b/src/testdir/test_channel.vim
index dd7ef4e..0885500 100644
--- a/src/testdir/test_channel.vim
+++ b/src/testdir/test_channel.vim
@@ -555,6 +555,97 @@
   endtry
 endfunc
 
+func Test_nl_write_out_file()
+  if !has('job')
+    return
+  endif
+  " TODO: make this work for MS-Windows
+  if !has('unix')
+    return
+  endif
+  call ch_log('Test_nl_write_out_file()')
+  let job = job_start(s:python . " test_channel_pipe.py",
+	\ {'out-io': 'file', 'out-name': 'Xoutput'})
+  call assert_equal("run", job_status(job))
+  try
+    let handle = job_getchannel(job)
+    call ch_sendraw(handle, "echo line one\n")
+    call ch_sendraw(handle, "echo line two\n")
+    call ch_sendraw(handle, "double this\n")
+    for i in range(50)
+      sleep 10m
+      if len(readfile('Xoutput')) > 2
+	break
+      endif
+    endfor
+    call assert_equal(['line one', 'line two', 'this', 'AND this'], readfile('Xoutput'))
+  finally
+    call job_stop(job)
+    call delete('Xoutput')
+  endtry
+endfunc
+
+func Test_nl_write_err_file()
+  if !has('job')
+    return
+  endif
+  " TODO: make this work for MS-Windows
+  if !has('unix')
+    return
+  endif
+  call ch_log('Test_nl_write_err_file()')
+  let job = job_start(s:python . " test_channel_pipe.py",
+	\ {'err-io': 'file', 'err-name': 'Xoutput'})
+  call assert_equal("run", job_status(job))
+  try
+    let handle = job_getchannel(job)
+    call ch_sendraw(handle, "echoerr line one\n")
+    call ch_sendraw(handle, "echoerr line two\n")
+    call ch_sendraw(handle, "doubleerr this\n")
+    for i in range(50)
+      sleep 10m
+      if len(readfile('Xoutput')) > 2
+	break
+      endif
+    endfor
+    call assert_equal(['line one', 'line two', 'this', 'AND this'], readfile('Xoutput'))
+  finally
+    call job_stop(job)
+    call delete('Xoutput')
+  endtry
+endfunc
+
+func Test_nl_write_both_file()
+  if !has('job')
+    return
+  endif
+  " TODO: make this work for MS-Windows
+  if !has('unix')
+    return
+  endif
+  call ch_log('Test_nl_write_both_file()')
+  let job = job_start(s:python . " test_channel_pipe.py",
+	\ {'out-io': 'file', 'out-name': 'Xoutput', 'err-io': 'out'})
+  call assert_equal("run", job_status(job))
+  try
+    let handle = job_getchannel(job)
+    call ch_sendraw(handle, "echoerr line one\n")
+    call ch_sendraw(handle, "echo line two\n")
+    call ch_sendraw(handle, "double this\n")
+    call ch_sendraw(handle, "doubleerr that\n")
+    for i in range(50)
+      sleep 10m
+      if len(readfile('Xoutput')) > 5
+	break
+      endif
+    endfor
+    call assert_equal(['line one', 'line two', 'this', 'AND this', 'that', 'AND that'], readfile('Xoutput'))
+  finally
+    call job_stop(job)
+    call delete('Xoutput')
+  endtry
+endfunc
+
 func Test_pipe_to_buffer()
   if !has('job')
     return
diff --git a/src/testdir/test_channel_pipe.py b/src/testdir/test_channel_pipe.py
index 2097d3e..d5da687 100644
--- a/src/testdir/test_channel_pipe.py
+++ b/src/testdir/test_channel_pipe.py
@@ -21,10 +21,13 @@
         if typed.startswith("echo "):
             print(typed[5:-1])
             sys.stdout.flush()
-        if typed.startswith("echoerr"):
-            print(typed[8:-1], file=sys.stderr)
-            sys.stderr.flush()
-        if typed.startswith("double"):
+        if typed.startswith("double "):
             print(typed[7:-1] + "\nAND " + typed[7:-1])
             sys.stdout.flush()
+        if typed.startswith("echoerr "):
+            print(typed[8:-1], file=sys.stderr)
+            sys.stderr.flush()
+        if typed.startswith("doubleerr "):
+            print(typed[10:-1] + "\nAND " + typed[10:-1], file=sys.stderr)
+            sys.stderr.flush()