1 files changed, 45 insertions, 0 deletions
diff --git a/src/testdir/test_changedtick.vim b/src/testdir/test_changedtick.vim
new file mode 100644
index 0000000000..f273f0f76e
--- /dev/null
+++ b/src/testdir/test_changedtick.vim
@@ -0,0 +1,45 @@
+" Tests for b:changedtick
+
+func Test_changedtick_increments()
+  new
+  " New buffer has an empty line, tick starts at 2.
+  let expected = 2
+  call assert_equal(expected, b:changedtick)
+  call assert_equal(expected, b:['changedtick'])
+  call setline(1, 'hello')
+  let expected += 1
+  call assert_equal(expected, b:changedtick)
+  call assert_equal(expected, b:['changedtick'])
+  undo
+  " Somehow undo counts as two changes.
+  let expected += 2
+  call assert_equal(expected, b:changedtick)
+  call assert_equal(expected, b:['changedtick'])
+  bwipe!
+endfunc
+
+func Test_changedtick_dict_entry()
+  let d = b:
+  call assert_equal(b:changedtick, d['changedtick'])
+endfunc
+
+func Test_changedtick_bdel()
+  new
+  let bnr = bufnr('%')
+  let v = b:changedtick
+  bdel
+  " Delete counts as a change too.
+  call assert_equal(v + 1, getbufvar(bnr, 'changedtick'))
+endfunc
+
+func Test_changedtick_fixed()
+  call assert_fails('let b:changedtick = 4', 'E46')
+  call assert_fails('let b:["changedtick"] = 4', 'E46')
+
+  call assert_fails('unlet b:changedtick', 'E795')
+  call assert_fails('unlet b:["changedtick"]', 'E46')
+
+  let d = b:
+  call assert_fails('unlet d["changedtick"]', 'E46')
+
+endfunc