patch 9.1.0599: Termdebug: still get E1023 when specifying arguments

Problem:  Termdebug: still get E1023 when specifying arguments and using
          a prompt buffer.
Solution: Use empty() instead of len().  Add a test.  Fix wrong order of
          arguments to assert_equal() in Test_termdebug_basic().
          (zeertzjq)

closes: #15288

Signed-off-by: zeertzjq <zeertzjq@outlook.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/testdir/test_termdebug.vim b/src/testdir/test_termdebug.vim
index 1095e11..ef29151 100644
--- a/src/testdir/test_termdebug.vim
+++ b/src/testdir/test_termdebug.vim
@@ -123,13 +123,13 @@
   " 60 is approx spaceBuffer * 3
   if winwidth(0) <= 78 + 60
     Var
-    call assert_equal(winnr(), winnr('$'))
-    call assert_equal(winlayout(), ['col', [['leaf', 1002], ['leaf', 1001], ['leaf', 1000], ['leaf', 1003 + cn]]])
+    call assert_equal(winnr('$'), winnr())
+    call assert_equal(['col', [['leaf', 1002], ['leaf', 1001], ['leaf', 1000], ['leaf', 1003 + cn]]], winlayout())
     let cn += 1
     bw!
     Asm
-    call assert_equal(winnr(), winnr('$'))
-    call assert_equal(winlayout(), ['col', [['leaf', 1002], ['leaf', 1001], ['leaf', 1000], ['leaf', 1003 + cn]]])
+    call assert_equal(winnr('$'), winnr())
+    call assert_equal(['col', [['leaf', 1002], ['leaf', 1001], ['leaf', 1000], ['leaf', 1003 + cn]]], winlayout())
     let cn += 1
     bw!
   endif
@@ -138,16 +138,16 @@
   let winw = winwidth(0)
   Var
   if winwidth(0) < winw
-    call assert_equal(winnr(), winnr('$') - 1)
-    call assert_equal(winlayout(), ['col', [['leaf', 1002], ['leaf', 1001], ['row', [['leaf', 1003 + cn], ['leaf', 1000]]]]])
+    call assert_equal(winnr('$') - 1, winnr())
+    call assert_equal(['col', [['leaf', 1002], ['leaf', 1001], ['row', [['leaf', 1003 + cn], ['leaf', 1000]]]]], winlayout())
     let cn += 1
     bw!
   endif
   let winw = winwidth(0)
   Asm
   if winwidth(0) < winw
-    call assert_equal(winnr(), winnr('$') - 1)
-    call assert_equal(winlayout(), ['col', [['leaf', 1002], ['leaf', 1001], ['row', [['leaf', 1003 + cn], ['leaf', 1000]]]]])
+    call assert_equal(winnr('$') - 1, winnr())
+    call assert_equal(['col', [['leaf', 1002], ['leaf', 1001], ['row', [['leaf', 1003 + cn], ['leaf', 1000]]]]], winlayout())
     let cn += 1
     bw!
   endif
@@ -160,6 +160,18 @@
   call WaitForAssert({-> assert_equal(1, winnr('$'))})
   call assert_equal([], sign_getplaced('', #{group: 'TermDebug'})[0].signs)
 
+  for use_prompt in [0, 1]
+    let g:termdebug_config = {}
+    let g:termdebug_config['use_prompt'] = use_prompt
+    TermdebugCommand ./XTD_basic arg args
+    call WaitForAssert({-> assert_equal(3, winnr('$'))})
+    wincmd t
+    quit!
+    redraw!
+    call WaitForAssert({-> assert_equal(1, winnr('$'))})
+    unlet g:termdebug_config
+  endfor
+
   call s:cleanup_files(bin_name)
   %bw!
 endfunc
diff --git a/src/version.c b/src/version.c
index acb4bad..48c7f74 100644
--- a/src/version.c
+++ b/src/version.c
@@ -705,6 +705,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    599,
+/**/
     598,
 /**/
     597,