viminfo: First version of ShaDa file dumping

What works:

1. ShaDa file dumping: header, registers, jump list, history, search patterns,
   substitute strings, variables.
2. ShaDa file reading: registers, global marks, variables.

Most was not tested.

TODO:

1. Merging.
2. Reading history, local marks, jump and buffer lists.
3. Documentation update.
4. Converting some data from &encoding.
5. Safer variant of dumping viminfo (dump to temporary file then rename).
6. Removing old viminfo code (currently masked with `#if 0` in a ShaDa file for
   reference).

1 files changed, 40 insertions, 0 deletions

diff --git a/test/functional/ex_getln/history_spec.lua b/test/functional/ex_getln/history_spec.lua
new file mode 100644
index 0000000000..c3ef56c8ad
--- /dev/null
+++ b/test/functional/ex_getln/history_spec.lua
@@ -0,0 +1,40 @@
+local helpers = require('test.functional.helpers')
+local clear, nvim, call, eq =
+  helpers.clear, helpers.nvim, helpers.call, helpers.eq
+
+describe('history support code', function()
+  before_each(clear)
+
+  local histadd = function(...) return call('histadd', ...) end
+  local histget = function(...) return call('histget', ...) end
+  local histdel = function(...) return call('histdel', ...) end
+
+  it('correctly clears start of the history', function()
+    -- Regression test: check absense of the memory leak when clearing start of 
+    -- the history using ex_getln.c/clr_history().
+    eq(1, histadd(':', 'foo'))
+    eq(1, histdel(':'))
+    eq('', histget(':', -1))
+  end)
+
+  it('correctly clears end of the history', function()
+    -- Regression test: check absense of the memory leak when clearing end of 
+    -- the history using ex_getln.c/clr_history().
+    nvim('set_option', 'history', 1)
+    eq(1, histadd(':', 'foo'))
+    eq(1, histdel(':'))
+    eq('', histget(':', -1))
+  end)
+
+  it('correctly removes item from history', function()
+    -- Regression test: check that ex_getln.c/del_history_idx() correctly clears 
+    -- history index after removing history entry. If it does not then deleting 
+    -- history will result in a double free.
+    eq(1, histadd(':', 'foo'))
+    eq(1, histadd(':', 'bar'))
+    eq(1, histadd(':', 'baz'))
+    eq(1, histdel(':', -2))
+    eq(1, histdel(':'))
+    eq('', histget(':', -1))
+  end)
+end)