diff --git a/src/testdir/mouse.vim b/src/testdir/mouse.vim
new file mode 100644
index 0000000..a28a439
--- /dev/null
+++ b/src/testdir/mouse.vim
@@ -0,0 +1,172 @@
+" Helper functions for generating mouse events
+
+" xterm2 and sgr always work, urxvt is optional.
+let g:Ttymouse_values = ['xterm2', 'sgr']
+if has('mouse_urxvt')
+  call add(g:Ttymouse_values, 'urxvt')
+endif
+
+" dec doesn't support all the functionality
+if has('mouse_dec')
+  let g:Ttymouse_dec = ['dec']
+else
+  let g:Ttymouse_dec = []
+endif
+
+" netterm only supports left click
+if has('mouse_netterm')
+  let g:Ttymouse_netterm = ['netterm']
+else
+  let g:Ttymouse_netterm = []
+endif
+
+" Helper function to emit a terminal escape code.
+func TerminalEscapeCode(code, row, col, m)
+  if &ttymouse ==# 'xterm2'
+    " need to use byte encoding here.
+    let str = list2str([a:code + 0x20, a:col + 0x20, a:row + 0x20])
+    if has('iconv')
+      let bytes = str->iconv('utf-8', 'latin1')
+    else
+      " Hopefully the numbers are not too big.
+      let bytes = str
+    endif
+    return "\<Esc>[M" .. bytes
+  elseif &ttymouse ==# 'sgr'
+    return printf("\<Esc>[<%d;%d;%d%s", a:code, a:col, a:row, a:m)
+  elseif &ttymouse ==# 'urxvt'
+    return printf("\<Esc>[%d;%d;%dM", a:code + 0x20, a:col, a:row)
+  endif
+endfunc
+
+func DecEscapeCode(code, down, row, col)
+    return printf("\<Esc>[%d;%d;%d;%d&w", a:code, a:down, a:row, a:col)
+endfunc
+
+func NettermEscapeCode(row, col)
+    return printf("\<Esc>}%d,%d\r", a:row, a:col)
+endfunc
+
+func MouseLeftClickCode(row, col)
+  if &ttymouse ==# 'dec'
+    return DecEscapeCode(2, 4, a:row, a:col)
+  elseif &ttymouse ==# 'netterm'
+    return NettermEscapeCode(a:row, a:col)
+  else
+    return TerminalEscapeCode(0, a:row, a:col, 'M')
+  endif
+endfunc
+
+func MouseLeftClick(row, col)
+  call feedkeys(MouseLeftClickCode(a:row, a:col), 'Lx!')
+endfunc
+
+func MouseMiddleClickCode(row, col)
+  if &ttymouse ==# 'dec'
+    return DecEscapeCode(4, 2, a:row, a:col)
+  else
+    return TerminalEscapeCode(1, a:row, a:col, 'M')
+  endif
+endfunc
+
+func MouseMiddleClick(row, col)
+  call feedkeys(MouseMiddleClickCode(a:row, a:col), 'Lx!')
+endfunc
+
+func MouseRightClickCode(row, col)
+  if &ttymouse ==# 'dec'
+    return DecEscapeCode(6, 1, a:row, a:col)
+  else
+    return TerminalEscapeCode(2, a:row, a:col, 'M')
+  endif
+endfunc
+
+func MouseRightClick(row, col)
+  call feedkeys(MouseRightClickCode(a:row, a:col), 'Lx!')
+endfunc
+
+func MouseCtrlLeftClickCode(row, col)
+  let ctrl = 0x10
+  return TerminalEscapeCode(0 + ctrl, a:row, a:col, 'M')
+endfunc
+
+func MouseCtrlLeftClick(row, col)
+  call feedkeys(MouseCtrlLeftClickCode(a:row, a:col), 'Lx!')
+endfunc
+
+func MouseCtrlRightClickCode(row, col)
+  let ctrl = 0x10
+  return TerminalEscapeCode(2 + ctrl, a:row, a:col, 'M')
+endfunc
+
+func MouseCtrlRightClick(row, col)
+  call feedkeys(MouseCtrlRightClickCode(a:row, a:col), 'Lx!')
+endfunc
+
+func MouseLeftReleaseCode(row, col)
+  if &ttymouse ==# 'dec'
+    return DecEscapeCode(3, 0, a:row, a:col)
+  elseif &ttymouse ==# 'netterm'
+    return ''
+  else
+    return TerminalEscapeCode(3, a:row, a:col, 'm')
+  endif
+endfunc
+
+func MouseLeftRelease(row, col)
+  call feedkeys(MouseLeftReleaseCode(a:row, a:col), 'Lx!')
+endfunc
+
+func MouseMiddleReleaseCode(row, col)
+  if &ttymouse ==# 'dec'
+    return DecEscapeCode(5, 0, a:row, a:col)
+  else
+    return TerminalEscapeCode(3, a:row, a:col, 'm')
+  endif
+endfunc
+
+func MouseMiddleRelease(row, col)
+  call feedkeys(MouseMiddleReleaseCode(a:row, a:col), 'Lx!')
+endfunc
+
+func MouseRightReleaseCode(row, col)
+  if &ttymouse ==# 'dec'
+    return DecEscapeCode(7, 0, a:row, a:col)
+  else
+    return TerminalEscapeCode(3, a:row, a:col, 'm')
+  endif
+endfunc
+
+func MouseRightRelease(row, col)
+  call feedkeys(MouseRightReleaseCode(a:row, a:col), 'Lx!')
+endfunc
+
+func MouseLeftDragCode(row, col)
+  if &ttymouse ==# 'dec'
+    return DecEscapeCode(1, 4, a:row, a:col)
+  else
+    return TerminalEscapeCode(0x20, a:row, a:col, 'M')
+  endif
+endfunc
+
+func MouseLeftDrag(row, col)
+  call feedkeys(MouseLeftDragCode(a:row, a:col), 'Lx!')
+endfunc
+
+func MouseWheelUpCode(row, col)
+  return TerminalEscapeCode(0x40, a:row, a:col, 'M')
+endfunc
+
+func MouseWheelUp(row, col)
+  call feedkeys(MouseWheelUpCode(a:row, a:col), 'Lx!')
+endfunc
+
+func MouseWheelDownCode(row, col)
+  return TerminalEscapeCode(0x41, a:row, a:col, 'M')
+endfunc
+
+func MouseWheelDown(row, col)
+  call feedkeys(MouseWheelDownCode(a:row, a:col), 'Lx!')
+endfunc
+
+" vim: shiftwidth=2 sts=2 expandtab