diff --git a/src/testdir/test_shift.vim b/src/testdir/test_shift.vim
index 370082f..f31c5a1 100644
--- a/src/testdir/test_shift.vim
+++ b/src/testdir/test_shift.vim
@@ -112,4 +112,805 @@
   call assert_fails('2,1<', 'E493:')
 endfunc
 
+" Test inserting a backspace at the start of a line.
+"
+" This is to verify the proper behavior of tabstop_start() as called from
+" ins_bs().
+"
+func Test_shift_ins_bs()
+  set backspace=indent,start
+  set softtabstop=11
+
+  call setline(1, repeat(" ", 33) . "word")
+  exe "norm! I\<BS>"
+  call assert_equal(repeat(" ", 22) . "word", getline(1))
+  call setline(1, repeat(" ", 23) . "word")
+  exe "norm! I\<BS>"
+  call assert_equal(repeat(" ", 22) . "word", getline(1))
+  exe "norm! I\<BS>"
+  call assert_equal(repeat(" ", 11) . "word", getline(1))
+
+  set backspace& softtabstop&
+  bw!
+endfunc
+
+" Test inserting a backspace at the start of a line, with 'varsofttabstop'.
+"
+func Test_shift_ins_bs_vartabs()
+  CheckFeature vartabs
+  set backspace=indent,start
+  set varsofttabstop=13,11,7
+
+  call setline(1, repeat(" ", 44) . "word")
+  exe "norm! I\<BS>"
+  call assert_equal(repeat(" ", 38) . "word", getline(1))
+  call setline(1, repeat(" ", 39) . "word")
+  exe "norm! I\<BS>"
+  call assert_equal(repeat(" ", 38) . "word", getline(1))
+  exe "norm! I\<BS>"
+  call assert_equal(repeat(" ", 31) . "word", getline(1))
+  exe "norm! I\<BS>"
+  call assert_equal(repeat(" ", 24) . "word", getline(1))
+  exe "norm! I\<BS>"
+  call assert_equal(repeat(" ", 13) . "word", getline(1))
+  exe "norm! I\<BS>"
+  call assert_equal(                  "word", getline(1))
+  exe "norm! I\<BS>"
+  call assert_equal(                  "word", getline(1))
+
+  set backspace& varsofttabstop&
+  bw!
+endfunc
+
+" Test the >> and << normal-mode commands.
+"
+func Test_shift_norm()
+  set expandtab                 " Don't want to worry about tabs vs. spaces in
+                                " results.
+
+  set shiftwidth=5
+  set tabstop=7
+
+  call setline(1, "  word")
+
+  " Shift by 'shiftwidth' right and left.
+
+  norm! >>
+  call assert_equal(repeat(" ",  7) . "word", getline(1))
+  norm! >>
+  call assert_equal(repeat(" ",  12) . "word", getline(1))
+  norm! >>
+  call assert_equal(repeat(" ",  17) . "word", getline(1))
+
+  norm! <<
+  call assert_equal(repeat(" ",  12) . "word", getline(1))
+  norm! <<
+  call assert_equal(repeat(" ",  7) . "word", getline(1))
+  norm! <<
+  call assert_equal(repeat(" ",  2) . "word", getline(1))
+  norm! <<
+  call assert_equal(repeat(" ",  0) . "word", getline(1))
+
+  " Shift by 'tabstop' right and left.
+
+  set shiftwidth=0
+  call setline(1, "  word")
+
+  norm! >>
+  call assert_equal(repeat(" ",  9) . "word", getline(1))
+  norm! >>
+  call assert_equal(repeat(" ",  16) . "word", getline(1))
+  norm! >>
+  call assert_equal(repeat(" ",  23) . "word", getline(1))
+
+  norm! <<
+  call assert_equal(repeat(" ",  16) . "word", getline(1))
+  norm! <<
+  call assert_equal(repeat(" ",  9) . "word", getline(1))
+  norm! <<
+  call assert_equal(repeat(" ",  2) . "word", getline(1))
+  norm! <<
+  call assert_equal(repeat(" ",  0) . "word", getline(1))
+
+  set expandtab& shiftwidth& tabstop&
+  bw!
+endfunc
+
+" Test the >> and << normal-mode commands, with 'vartabstop'.
+"
+func Test_shift_norm_vartabs()
+  CheckFeature vartabs
+  set expandtab                 " Don't want to worry about tabs vs. spaces in
+                                " results.
+
+  set shiftwidth=0
+  set vartabstop=19,17,11
+
+  " Shift by 'vartabstop' right and left.
+
+  call setline(1, "  word")
+
+  norm! >>
+  call assert_equal(repeat(" ",  21) . "word", getline(1))
+  norm! >>
+  call assert_equal(repeat(" ",  38) . "word", getline(1))
+  norm! >>
+  call assert_equal(repeat(" ",  49) . "word", getline(1))
+  norm! >>
+  call assert_equal(repeat(" ",  60) . "word", getline(1))
+
+  norm! <<
+  call assert_equal(repeat(" ",  49) . "word", getline(1))
+  norm! <<
+  call assert_equal(repeat(" ",  38) . "word", getline(1))
+  norm! <<
+  call assert_equal(repeat(" ",  21) . "word", getline(1))
+  norm! <<
+  call assert_equal(repeat(" ",  2) . "word", getline(1))
+  norm! <<
+  call assert_equal(repeat(" ",  0) . "word", getline(1))
+
+  set expandtab& shiftwidth& vartabstop&
+  bw!
+endfunc
+
+" Test the >> and << normal-mode commands with 'shiftround'.
+"
+func Test_shift_norm_round()
+  set expandtab                 " Don't want to worry about tabs vs. spaces in
+                                " results.
+
+  set shiftround
+  set shiftwidth=5
+  set tabstop=7
+
+  call setline(1, "word")
+
+  " Shift by 'shiftwidth' right and left.
+
+  exe "norm! I  "
+  norm! >>
+  call assert_equal(repeat(" ",  5) . "word", getline(1))
+  exe "norm! I  "
+  norm! >>
+  call assert_equal(repeat(" ",  10) . "word", getline(1))
+  exe "norm! I  "
+  norm! >>
+  call assert_equal(repeat(" ",  15) . "word", getline(1))
+  norm! >>
+  call assert_equal(repeat(" ",  20) . "word", getline(1))
+  norm! >>
+  call assert_equal(repeat(" ",  25) . "word", getline(1))
+
+  norm! <<
+  call assert_equal(repeat(" ",  20) . "word", getline(1))
+  norm! <<
+  call assert_equal(repeat(" ",  15) . "word", getline(1))
+  norm! <<
+  call assert_equal(repeat(" ",  10) . "word", getline(1))
+  exe "norm! I  "
+  norm! <<
+  call assert_equal(repeat(" ",  10) . "word", getline(1))
+
+  call setline(1, repeat(" ", 7) . "word")
+  norm! <<
+  call assert_equal(repeat(" ",  5) . "word", getline(1))
+  norm! <<
+  call assert_equal(repeat(" ",  0) . "word", getline(1))
+  norm! <<
+  call assert_equal(repeat(" ",  0) . "word", getline(1))
+  call setline(1, repeat(" ", 2) . "word")
+  norm! <<
+  call assert_equal(repeat(" ",  0) . "word", getline(1))
+
+  " Shift by 'tabstop' right and left.
+
+  set shiftwidth=0
+  call setline(1, "word")
+
+  exe "norm! I  "
+  norm! >>
+  call assert_equal(repeat(" ",  7) . "word", getline(1))
+  exe "norm! I  "
+  norm! >>
+  call assert_equal(repeat(" ",  14) . "word", getline(1))
+  exe "norm! I  "
+  norm! >>
+  call assert_equal(repeat(" ",  21) . "word", getline(1))
+  norm! >>
+  call assert_equal(repeat(" ",  28) . "word", getline(1))
+  norm! >>
+  call assert_equal(repeat(" ",  35) . "word", getline(1))
+
+  norm! <<
+  call assert_equal(repeat(" ",  28) . "word", getline(1))
+  norm! <<
+  call assert_equal(repeat(" ",  21) . "word", getline(1))
+  norm! <<
+  call assert_equal(repeat(" ",  14) . "word", getline(1))
+  exe "norm! I  "
+  norm! <<
+  call assert_equal(repeat(" ",  14) . "word", getline(1))
+
+  call setline(1, repeat(" ", 9) . "word")
+  norm! <<
+  call assert_equal(repeat(" ",  7) . "word", getline(1))
+  norm! <<
+  call assert_equal(repeat(" ",  0) . "word", getline(1))
+  norm! <<
+  call assert_equal(repeat(" ",  0) . "word", getline(1))
+  call setline(1, repeat(" ", 2) . "word")
+  norm! <<
+  call assert_equal(repeat(" ",  0) . "word", getline(1))
+
+  set expandtab& shiftround& shiftwidth& tabstop&
+  bw!
+endfunc
+
+" Test the >> and << normal-mode commands with 'shiftround' and 'vartabstop'.
+"
+func Test_shift_norm_round_vartabs()
+  CheckFeature vartabs
+  set expandtab                 " Don't want to worry about tabs vs. spaces in
+                                " results.
+
+  set shiftround
+  set shiftwidth=0
+  set vartabstop=19,17,11
+
+  " Shift by 'vartabstop' right and left.
+
+  call setline(1, "word")
+
+  exe "norm! I  "
+  norm! >>
+  call assert_equal(repeat(" ",  19) . "word", getline(1))
+  exe "norm! I  "
+  norm! >>
+  call assert_equal(repeat(" ",  36) . "word", getline(1))
+  exe "norm! I  "
+  norm! >>
+  call assert_equal(repeat(" ",  47) . "word", getline(1))
+  exe "norm! I  "
+  norm! >>
+  call assert_equal(repeat(" ",  58) . "word", getline(1))
+
+  exe "norm! I  "
+  norm! <<
+  call assert_equal(repeat(" ",  58) . "word", getline(1))
+  norm! <<
+  call assert_equal(repeat(" ",  47) . "word", getline(1))
+  norm! <<
+  call assert_equal(repeat(" ",  36) . "word", getline(1))
+  norm! <<
+  call assert_equal(repeat(" ",  19) . "word", getline(1))
+  exe "norm! I  "
+  norm! <<
+  call assert_equal(repeat(" ",  19) . "word", getline(1))
+  norm! <<
+  call assert_equal(repeat(" ",  0) . "word", getline(1))
+  exe "norm! I  "
+  call assert_equal(repeat(" ",  2) . "word", getline(1))
+  norm! <<
+  call assert_equal(repeat(" ",  0) . "word", getline(1))
+  norm! <<
+  call assert_equal(repeat(" ",  0) . "word", getline(1))
+
+  set expandtab& shiftround& shiftwidth& vartabstop&
+  bw!
+endfunc
+
+" Test the V> and V< visual-mode commands.
+"
+" See ":help v_<" and ":help v_>".  See also the last paragraph of "3. Simple
+" changes", ":help simple-change", immediately above "4. Complex changes",
+" ":help complex-change".
+"
+func Test_shift_vis()
+  set expandtab                 " Don't want to worry about tabs vs. spaces in
+                                " results.
+
+  set shiftwidth=5
+  set tabstop=7
+
+  call setline(1, "  word")
+
+  " Shift by 'shiftwidth' right and left.
+
+  norm! V>
+  call assert_equal(repeat(" ",  7) . "word", getline(1))
+  norm! V2>
+  call assert_equal(repeat(" ",  17) . "word", getline(1))
+  norm! V3>
+  call assert_equal(repeat(" ",  32) . "word", getline(1))
+
+  norm! V<
+  call assert_equal(repeat(" ",  27) . "word", getline(1))
+  norm! V2<
+  call assert_equal(repeat(" ",  17) . "word", getline(1))
+  norm! V3<
+  call assert_equal(repeat(" ",  2) . "word", getline(1))
+  norm! V<
+  call assert_equal(repeat(" ",  0) . "word", getline(1))
+  norm! V3<
+  call assert_equal(repeat(" ",  0) . "word", getline(1))
+
+  " Shift by 'tabstop' right and left.
+
+  set shiftwidth=0
+  call setline(1, "  word")
+
+  norm! V>
+  call assert_equal(repeat(" ",  9) . "word", getline(1))
+  norm! V2>
+  call assert_equal(repeat(" ",  23) . "word", getline(1))
+  norm! V3>
+  call assert_equal(repeat(" ",  44) . "word", getline(1))
+
+  norm! V<
+  call assert_equal(repeat(" ",  37) . "word", getline(1))
+  norm! V2<
+  call assert_equal(repeat(" ",  23) . "word", getline(1))
+  norm! V3<
+  call assert_equal(repeat(" ",  2) . "word", getline(1))
+  norm! V<
+  call assert_equal(repeat(" ",  0) . "word", getline(1))
+  norm! V3<
+  call assert_equal(repeat(" ",  0) . "word", getline(1))
+
+  set expandtab& shiftwidth& tabstop&
+  bw!
+endfunc
+
+" Test the V> and V< visual-mode commands, with 'vartabstop'.
+"
+" See ":help v_<" and ":help v_>".  See also the last paragraph of "3. Simple
+" changes", ":help simple-change", immediately above "4. Complex changes",
+" ":help complex-change".
+"
+func Test_shift_vis_vartabs()
+  CheckFeature vartabs
+  set expandtab                 " Don't want to worry about tabs vs. spaces in
+                                " results.
+
+  set shiftwidth=0
+  set vartabstop=19,17,11
+
+  " Shift by 'vartabstop' right and left.
+
+  call setline(1, "  word")
+
+  norm! V>
+  call assert_equal(repeat(" ",  21) . "word", getline(1))
+  norm! V2>
+  call assert_equal(repeat(" ",  49) . "word", getline(1))
+  norm! V3>
+  call assert_equal(repeat(" ",  82) . "word", getline(1))
+
+  norm! V<
+  call assert_equal(repeat(" ",  71) . "word", getline(1))
+  norm! V2<
+  call assert_equal(repeat(" ",  49) . "word", getline(1))
+  norm! V3<
+  call assert_equal(repeat(" ",  2) . "word", getline(1))
+  norm! V<
+  call assert_equal(repeat(" ",  0) . "word", getline(1))
+  norm! V3<
+  call assert_equal(repeat(" ",  0) . "word", getline(1))
+
+  set expandtab& shiftwidth& vartabstop&
+  bw!
+endfunc
+
+" Test the V> and V< visual-mode commands with 'shiftround'.
+"
+func Test_shift_vis_round()
+  set expandtab                 " Don't want to worry about tabs vs. spaces in
+                                " results.
+
+  set shiftround
+  set shiftwidth=5
+  set tabstop=7
+
+  call setline(1, "word")
+
+  " Shift by 'shiftwidth' right and left.
+
+  exe "norm! I  "
+  norm! V>
+  call assert_equal(repeat(" ",  5) . "word", getline(1))
+  exe "norm! I  "
+  norm! V2>
+  call assert_equal(repeat(" ",  15) . "word", getline(1))
+  exe "norm! I  "
+  norm! V3>
+  call assert_equal(repeat(" ",  30) . "word", getline(1))
+
+  exe "norm! I  "
+  norm! V2<
+  call assert_equal(repeat(" ",  25) . "word", getline(1))
+  norm! V3<
+  call assert_equal(repeat(" ",  10) . "word", getline(1))
+  norm! V<
+  call assert_equal(repeat(" ",  5) . "word", getline(1))
+  norm! V<
+  call assert_equal(repeat(" ",  0) . "word", getline(1))
+  norm! V3<
+  call assert_equal(repeat(" ",  0) . "word", getline(1))
+
+  " Shift by 'tabstop' right and left.
+
+  set shiftwidth=0
+  call setline(1, "word")
+
+  exe "norm! I  "
+  norm! V>
+  call assert_equal(repeat(" ",  7) . "word", getline(1))
+  exe "norm! I  "
+  norm! V2>
+  call assert_equal(repeat(" ",  21) . "word", getline(1))
+  exe "norm! I  "
+  norm! V3>
+  call assert_equal(repeat(" ",  42) . "word", getline(1))
+
+  exe "norm! I  "
+  norm! V<
+  call assert_equal(repeat(" ",  42) . "word", getline(1))
+  norm! V<
+  call assert_equal(repeat(" ",  35) . "word", getline(1))
+  norm! V2<
+  call assert_equal(repeat(" ",  21) . "word", getline(1))
+  norm! V3<
+  call assert_equal(repeat(" ",  0) . "word", getline(1))
+  norm! V<
+  call assert_equal(repeat(" ",  0) . "word", getline(1))
+  norm! V3<
+  call assert_equal(repeat(" ",  0) . "word", getline(1))
+
+  call setline(1, "  word")
+  norm! V<
+  call assert_equal(repeat(" ",  0) . "word", getline(1))
+
+
+  set expandtab& shiftround& shiftwidth& tabstop&
+  bw!
+endfunc
+
+" Test the V> and V< visual-mode commands with 'shiftround' and 'vartabstop'.
+"
+func Test_shift_vis_round_vartabs()
+  CheckFeature vartabs
+  set expandtab                 " Don't want to worry about tabs vs. spaces in
+                                " results.
+
+  set shiftround
+  set shiftwidth=0
+  set vartabstop=19,17,11
+
+  " Shift by 'vartabstop' right and left.
+
+  call setline(1, "word")
+
+  exe "norm! I  "
+  norm! V>
+  call assert_equal(repeat(" ",  19) . "word", getline(1))
+  exe "norm! I  "
+  norm! V3>
+  call assert_equal(repeat(" ",  58) . "word", getline(1))
+
+  exe "norm! I  "
+  norm! V2<
+  call assert_equal(repeat(" ",  47) . "word", getline(1))
+  exe "norm! I  "
+  norm! V3<
+  call assert_equal(repeat(" ",  19) . "word", getline(1))
+  exe "norm! I  "
+  norm! V3<
+  call assert_equal(repeat(" ",  0) . "word", getline(1))
+  exe "norm! I  "
+  norm! V<
+  call assert_equal(repeat(" ",  0) . "word", getline(1))
+
+  set expandtab& shiftround& shiftwidth& vartabstop&
+  bw!
+endfunc
+
+" Test the :> and :< ex-mode commands.
+"
+func Test_shift_ex()
+  set expandtab                 " Don't want to worry about tabs vs. spaces in
+                                " results.
+
+  set shiftwidth=5
+  set tabstop=7
+
+  call setline(1, "  word")
+
+  " Shift by 'shiftwidth' right and left.
+
+  >
+  call assert_equal(repeat(" ",  7) . "word", getline(1))
+  >>
+  call assert_equal(repeat(" ",  17) . "word", getline(1))
+  >>>
+  call assert_equal(repeat(" ",  32) . "word", getline(1))
+
+  <<<<
+  call assert_equal(repeat(" ",  12) . "word", getline(1))
+  <
+  call assert_equal(repeat(" ",  7) . "word", getline(1))
+  <
+  call assert_equal(repeat(" ",  2) . "word", getline(1))
+  <
+  call assert_equal(repeat(" ",  0) . "word", getline(1))
+
+  " Shift by 'tabstop' right and left.
+
+  set shiftwidth=0
+  call setline(1, "  word")
+
+  >
+  call assert_equal(repeat(" ",  9) . "word", getline(1))
+  >>
+  call assert_equal(repeat(" ",  23) . "word", getline(1))
+  >>>
+  call assert_equal(repeat(" ",  44) . "word", getline(1))
+
+  <<<<
+  call assert_equal(repeat(" ",  16) . "word", getline(1))
+  <<
+  call assert_equal(repeat(" ",  2) . "word", getline(1))
+  <
+  call assert_equal(repeat(" ",  0) . "word", getline(1))
+
+  set expandtab& shiftwidth& tabstop&
+  bw!
+endfunc
+
+" Test the :> and :< ex-mode commands, with vartabstop.
+"
+func Test_shift_ex_vartabs()
+  CheckFeature vartabs
+  set expandtab                 " Don't want to worry about tabs vs. spaces in
+                                " results.
+
+  set shiftwidth=0
+  set vartabstop=19,17,11
+
+  " Shift by 'vartabstop' right and left.
+
+  call setline(1, "  word")
+
+  >
+  call assert_equal(repeat(" ",  21) . "word", getline(1))
+  >>
+  call assert_equal(repeat(" ",  49) . "word", getline(1))
+  >>>
+  call assert_equal(repeat(" ",  82) . "word", getline(1))
+
+  <<<<
+  call assert_equal(repeat(" ",  38) . "word", getline(1))
+  <<
+  call assert_equal(repeat(" ",  2) . "word", getline(1))
+  <
+  call assert_equal(repeat(" ",  0) . "word", getline(1))
+
+  set expandtab& shiftwidth& vartabstop&
+  bw!
+endfunc
+
+" Test the :> and :< ex-mode commands with 'shiftround'.
+"
+func Test_shift_ex_round()
+  set expandtab                 " Don't want to worry about tabs vs. spaces in
+                                " results.
+
+  set shiftround
+  set shiftwidth=5
+  set tabstop=7
+
+  call setline(1, "word")
+
+  " Shift by 'shiftwidth' right and left.
+
+  exe "norm! I  "
+  >
+  call assert_equal(repeat(" ",  5) . "word", getline(1))
+  exe "norm! I  "
+  >>
+  call assert_equal(repeat(" ",  15) . "word", getline(1))
+  exe "norm! I  "
+  >>>
+  call assert_equal(repeat(" ",  30) . "word", getline(1))
+
+  exe "norm! I  "
+  <<<<
+  call assert_equal(repeat(" ",  15) . "word", getline(1))
+  exe "norm! I  "
+  <<
+  call assert_equal(repeat(" ",  10) . "word", getline(1))
+  <<
+  call assert_equal(repeat(" ",  0) . "word", getline(1))
+  >>
+  <<<
+  call assert_equal(repeat(" ",  0) . "word", getline(1))
+
+  " Shift by 'tabstop' right and left.
+
+  set shiftwidth=0
+  call setline(1, "word")
+
+  exe "norm! I  "
+  >
+  call assert_equal(repeat(" ",  7) . "word", getline(1))
+  exe "norm! I  "
+  >>
+  call assert_equal(repeat(" ",  21) . "word", getline(1))
+  exe "norm! I  "
+  >>>
+  call assert_equal(repeat(" ",  42) . "word", getline(1))
+
+  exe "norm! I  "
+  <<<<
+  call assert_equal(repeat(" ",  21) . "word", getline(1))
+  exe "norm! I  "
+  <<
+  call assert_equal(repeat(" ",  14) . "word", getline(1))
+  exe "norm! I  "
+  <<<
+  call assert_equal(repeat(" ",  0) . "word", getline(1))
+  >>
+  <<<
+  call assert_equal(repeat(" ",  0) . "word", getline(1))
+
+  set expandtab& shiftround& shiftwidth& tabstop&
+  bw!
+endfunc
+
+" Test the :> and :< ex-mode commands with 'shiftround' and 'vartabstop'.
+"
+func Test_shift_ex_round_vartabs()
+  CheckFeature vartabs
+  set expandtab                 " Don't want to worry about tabs vs. spaces in
+                                " results.
+
+  set shiftround
+  set shiftwidth=0
+  set vartabstop=19,17,11
+
+  " Shift by 'vartabstop' right and left.
+
+  call setline(1, "word")
+
+  exe "norm! I  "
+  >
+  call assert_equal(repeat(" ",  19) . "word", getline(1))
+  exe "norm! I  "
+  >>
+  call assert_equal(repeat(" ",  47) . "word", getline(1))
+  >>>
+  call assert_equal(repeat(" ",  80) . "word", getline(1))
+
+  <<<<
+  call assert_equal(repeat(" ",  36) . "word", getline(1))
+  exe "norm! I  "
+  <<
+  call assert_equal(repeat(" ",  19) . "word", getline(1))
+  exe "norm! I  "
+  <<
+  call assert_equal(repeat(" ",  0) . "word", getline(1))
+  <
+  call assert_equal(repeat(" ",  0) . "word", getline(1))
+
+  set expandtab& shiftround& shiftwidth& vartabstop&
+  bw!
+endfunc
+
+" Test shifting lines with <C-T> and <C-D>.
+"
+func Test_shift_ins()
+  set expandtab                 " Don't want to worry about tabs vs. spaces in
+                                " results.
+
+  set shiftwidth=5
+  set tabstop=7
+
+  " Shift by 'shiftwidth' right and left.
+
+  call setline(1, repeat(" ", 7) . "word")
+  exe "norm! 9|i\<C-T>"
+  call assert_equal(repeat(" ", 10) . "word", getline(1))
+  exe "norm! A\<C-T>"
+  call assert_equal(repeat(" ", 15) . "word", getline(1))
+  exe "norm! I  \<C-T>"
+  call assert_equal(repeat(" ", 20) . "word", getline(1))
+
+  exe "norm! I  \<C-D>"
+  call assert_equal(repeat(" ", 20) . "word", getline(1))
+  exe "norm! I  "
+  exe "norm! 24|i\<C-D>"
+  call assert_equal(repeat(" ", 20) . "word", getline(1))
+  exe "norm! A\<C-D>"
+  call assert_equal(repeat(" ", 15) . "word", getline(1))
+  exe "norm! I  "
+  exe "norm! A\<C-D>\<C-D>"
+  call assert_equal(repeat(" ", 10) . "word", getline(1))
+  exe "norm! I\<C-D>\<C-D>\<C-D>"
+  call assert_equal(repeat(" ", 0) . "word", getline(1))
+  exe "norm! I\<C-D>"
+  call assert_equal(repeat(" ", 0) . "word", getline(1))
+
+  " Shift by 'tabstop' right and left.
+
+  set shiftwidth=0
+  call setline(1, "word")
+
+  call setline(1, repeat(" ", 9) . "word")
+  exe "norm! 11|i\<C-T>"
+  call assert_equal(repeat(" ", 14) . "word", getline(1))
+  exe "norm! A\<C-T>"
+  call assert_equal(repeat(" ", 21) . "word", getline(1))
+  exe "norm! I  \<C-T>"
+  call assert_equal(repeat(" ", 28) . "word", getline(1))
+
+  exe "norm! I  \<C-D>"
+  call assert_equal(repeat(" ", 28) . "word", getline(1))
+  exe "norm! I  "
+  exe "norm! 32|i\<C-D>"
+  call assert_equal(repeat(" ", 28) . "word", getline(1))
+  exe "norm! A\<C-D>"
+  call assert_equal(repeat(" ", 21) . "word", getline(1))
+  exe "norm! I  "
+  exe "norm! A\<C-D>\<C-D>"
+  call assert_equal(repeat(" ", 14) . "word", getline(1))
+  exe "norm! I\<C-D>\<C-D>\<C-D>"
+  call assert_equal(repeat(" ", 0) . "word", getline(1))
+  exe "norm! I\<C-D>"
+  call assert_equal(repeat(" ", 0) . "word", getline(1))
+
+  set expandtab& shiftwidth& tabstop&
+  bw!
+endfunc
+
+" Test shifting lines with <C-T> and <C-D>, with 'vartabstop'.
+"
+func Test_shift_ins_vartabs()
+  CheckFeature vartabs
+  set expandtab                 " Don't want to worry about tabs vs. spaces in
+                                " results.
+
+  set shiftwidth=0
+  set vartabstop=19,17,11
+
+  " Shift by 'vartabstop' right and left.
+
+  call setline(1, "word")
+
+  call setline(1, repeat(" ", 9) . "word")
+  exe "norm! 11|i\<C-T>"
+  call assert_equal(repeat(" ", 19) . "word", getline(1))
+  exe "norm! A\<C-T>"
+  call assert_equal(repeat(" ", 36) . "word", getline(1))
+  exe "norm! I  \<C-T>"
+  call assert_equal(repeat(" ", 47) . "word", getline(1))
+
+  exe "norm! I  \<C-D>"
+  call assert_equal(repeat(" ", 47) . "word", getline(1))
+  exe "norm! I  "
+  exe "norm! 51|i\<C-D>"
+  call assert_equal(repeat(" ", 47) . "word", getline(1))
+  exe "norm! A\<C-D>"
+  call assert_equal(repeat(" ", 36) . "word", getline(1))
+  exe "norm! I  "
+  exe "norm! A\<C-D>\<C-D>"
+  call assert_equal(repeat(" ", 19) . "word", getline(1))
+  exe "norm! I\<C-D>\<C-D>\<C-D>"
+  call assert_equal(repeat(" ", 0) . "word", getline(1))
+  exe "norm! I\<C-D>"
+  call assert_equal(repeat(" ", 0) . "word", getline(1))
+
+  set expandtab& shiftwidth& vartabstop&
+  bw!
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab