runtime(termdebug): check for gdb file/dir before using as buffer name

Add test so that this doesn't regress.

fixes: #12718
closes: #14792

Signed-off-by: Ubaldo Tiberi <ubaldo.tiberi@volvo.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

src/testdir/test_termdebug.vim

@@ -300,4 +300,43 @@ func Test_termdebug_mapping()
   %bw!
 endfunc
 
+func Test_termdebug_bufnames()
+  " Test if user has filename/folders named gdb, Termdebug-gdb-console,
+  " etc. in the current directory
+  let g:termdebug_config = {}
+  let g:termdebug_config['use_prompt'] = 1
+  let filename = 'gdb'
+  let replacement_filename = 'Termdebug-gdb-console'
+
+  call writefile(['This', 'is', 'a', 'test'], filename, 'D')
+  " Throw away the file once the test has done.
+  Termdebug
+  " Once termdebug has completed the startup you should have 3 windows on screen
+  call WaitForAssert({-> assert_equal(3, winnr('$'))})
+  " A file named filename already exists in the working directory,
+  " hence you must call the newly created buffer differently
+  call WaitForAssert({-> assert_false(bufexists(filename))})
+  call WaitForAssert({-> assert_true(bufexists(replacement_filename))})
+  quit!
+  call WaitForAssert({-> assert_equal(1, winnr('$'))})
+
+  " Check if error message is in :message
+  let g:termdebug_config['disasm_window'] = 1
+  let filename = 'Termdebug-asm-listing'
+  call writefile(['This', 'is', 'a', 'test'], filename, 'D')
+  " Check only the head of the error message
+  let error_message = "You have a file/folder named '" .. filename .. "'"
+  Termdebug
+  " Once termdebug has completed the startup you should have 4 windows on screen
+  call WaitForAssert({-> assert_equal(4, winnr('$'))})
+  call WaitForAssert({-> assert_notequal(-1, stridx(execute('messages'), error_message))})
+  quit!
+  wincmd b
+  wincmd q
+  call WaitForAssert({-> assert_equal(1, winnr('$'))})
+
+  unlet g:termdebug_config
+endfunc
+
+
 " vim: shiftwidth=2 sts=2 expandtab