add Lua lang

lua/README.md

@@ -0,0 +1,46 @@
+# Gilded Rose starting position in Lua
+
+I assume you have installed [Lua](https://lua.org/start.html) on your system (version >= 5.1).
+
+## Install
+
+If you want to use [LuaRocks](https://luarocks.org/) there is a config file that should install the dependencies nicely:
+
+```sh
+$ luarocks install --only-deps gildedrose-dev-1.rockspec
+```
+
+## Run unit tests from the command line
+
+The tests use the [Busted](https://github.com/lunarmodules/busted) tool.
+
+```sh
+$ busted
+```
+
+For coverage you'll need to install [LuaCov](https://github.com/lunarmodules/luacov)
+
+```sh
+$ busted --coverage
+$ luacov # generate the report
+```
+
+## Run the TextTest fixture on the command line
+
+```sh
+$ lua src/main.lua 10
+```
+
+## Run the TextTest approval test that comes with this project
+
+There are instructions in the [TextTest Readme](../texttests/README.md) for setting up TextTest.
+You will need to specify the executable in [config.gr](../texttests/config.gr).
+Uncomment this line to use it:
+
+```
+executable:${TEXTTEST_HOME}/lua/texttest
+```
+
+The TextTest fixture use the `./texttest` executable as a hack to make the `require` work.
+Lua does not have relative `require` and I did not find a simple way to implement them so the test need to run from the `./lua` directory.
+I will improve this in the future if I learn how to do it better :)