Add first set of basic lua api tests

There are two types of lua tests here:

1. Tests are formed from a <test>.in, <test>.ref and <test>.out triplet. The
   <test>.in file is opened by vis, some operatations are performed and the
   modified file is written to <test>.out. The new <test>.out is compared to
   <test>.ref and the test passes if they are identical.

2. Tests are formed from a single <test>.true file. This file is created by the
   lua code in the test. It contains a single line per test case, this single
   line should be `true` if the test case passed. The <test>.true file is
   checked to ensure it contains only `true` lines and if so, the test passes.

1 files changed, 127 insertions, 0 deletions

diff --git a/lua/utils.lua b/lua/utils.lua
new file mode 100644
index 0000000..134b2a6
--- /dev/null
+++ b/lua/utils.lua
@@ -0,0 +1,127 @@
+-- table_cmp - return true if table1 is the same as table2
+table_cmp = function(table1, table2)
+	if type(table1) ~= 'table' or type(table2) ~= 'table' then
+		return false
+	end
+	if #table1 ~= #table2 then
+		return false
+	end
+	for i, item in pairs(table1) do
+		if item ~= table2[i] then
+			return false
+		end
+	end
+	return true
+end
+
+-- strcasecmp - compare strings case-insensitively
+strcasecmp = function(str1, str2)
+	if type(str1) ~= 'string' or type(str2) ~= 'string' then
+		return false
+	end
+	str1 = string.lower(str1)
+	str2 = string.lower(str2)
+	return str1 == str2
+end
+
+-- Setline - Set lines starting at [startline] to [lines]
+--         - [startline] can be '.' to set the current line
+--         - [startline] can be '$' to set the last line in the buffer
+--         - [lines] can be left nil in which case, set lines to empty
+setline = function(win, startline, lines)
+	if startline == '.' then
+		startline = win.cursor.line
+	elseif startline == '$' then
+		startline = #win.file.lines
+	end
+
+	if type(lines) == 'string' then
+		lines = {lines}
+	end
+
+	for i, line in pairs(lines or {}) do
+		i = i + ((startline - 1) or 0)
+		win.file.lines[i] = line
+	end
+end
+
+-- Delete - Remove [number] lines starting at [startline]
+--        - [number] can be left nil to remove single line
+--        - [startline] can be '.' to delete the current line
+--        - [startline] can be '$' to delete the last line in the buffer
+--        - [startline] can be '%' to empty the buffer
+delete = function(win, startline, number)
+	if startline == '.' then
+		startline = win.cursor.line
+	elseif startline == '$' then
+		startline = #win.file.lines
+	elseif startline == '%' then
+		startline = 1
+		number = #win.file.lines
+	end
+
+	-- Get position in file of startline
+	win.cursor:to(startline, 0)
+	startpos = win.cursor.pos
+
+	-- Get position in file of endline, or delete single line
+	number = number or 1
+	win.cursor:to(startline + number, 0)
+	endpos = win.cursor.pos
+
+	-- Delete lines
+	len = endpos - startpos
+	win.file:delete(startpos, len)
+end
+
+-- Getline - Return a table of [number] lines starting from [startline]
+--         - [startline] can be '.' to return the current line
+--         - [startline] can be '$' to return the last line in the buffer
+--         - [startline] can be '%' to return the whole buffer
+--         - [number] can be left nil, in which case return a string
+--         containing line [startline]
+getline = function(win, startline, number)
+	if startline == '.' then
+		startline = win.cursor.line
+	elseif startline == '$' or startline > #win.file.lines then
+		startline = #win.file.lines
+	elseif startline == '%' then
+		startline = 1
+		number = #win.file.lines
+	elseif startline <= 0 then
+		startline = 1
+	end
+
+	if number == nil then
+		return win.file.lines[startline]
+	else
+		lines = {}
+		for i = startline, startline + number - 1, 1 do
+			table.insert(lines, win.file.lines[i])
+		end
+		return lines
+	end
+end
+
+-- Append - Insert lines after given line number
+--        - [line] can be either string or table
+--        - [startline] can be '.' to append after the current line
+--        - [startline] can be '$' to append after the last line in the buffer
+append = function(win, startline, lines)
+	if startline == '.' then
+		win.cursor:to(win.cursor.line + 1,  0)
+	elseif startline == '$' or startline > #win.file.lines then
+		win.cursor:to(#win.file.lines + 1, 0)
+	else
+		win.cursor:to(startline + 1, 0)
+	end
+	pos = win.cursor.pos
+
+	if type(lines) == 'table' then
+		lines = table.concat(lines, "\n") .. "\n"
+	elseif type(lines) == 'string' then
+		lines = lines .. '\n'
+	end
+
+	win.file:insert(pos, lines)
+end