lua: test the interpreter

Test with:
nix-build -A lua.tests pass

Tests are very limited for now, goal is mostly to put the infra into
place and enrich the tests when dealing with lua issues.
add luaPath/luaCpath as passthrough
makes it easier to generate LUA_PATH/LUA_CPATH

pkgs/development/interpreters/lua-5/default.nix

@@ -69,6 +69,8 @@ let
         inherit executable luaversion sourceVersion;
         luaOnBuild = luaOnBuildForHost.override { inherit packageOverrides; self = luaOnBuild; };
 
+        tests = callPackage ./tests { inherit (luaPackages) wrapLua; };
+
         inherit luaAttr;
   };
 

pkgs/development/interpreters/lua-5/tests/assert.sh

@@ -0,0 +1,16 @@
+# Always failing assertion with a message.
+#
+# Example:
+#     fail "It should have been but it wasn't to be"
+function fail() {
+    echo "$1"
+    exit 1
+}
+
+
+function assertStringEqual {
+
+    if ! diff <(echo "$1") <(echo "$2") ; then
+        fail "Strings differ"
+    fi
+}

pkgs/development/interpreters/lua-5/tests/default.nix

@@ -0,0 +1,50 @@
+{ lua
+, hello
+, wrapLua
+, lib, fetchFromGitHub
+, fetchFromGitLab
+, pkgs
+}:
+let
+
+  runTest = lua: { name, command }:
+    pkgs.runCommandLocal "test-${lua.name}" ({
+      nativeBuildInputs = [lua];
+      meta.platforms = lua.meta.platforms;
+    }) (''
+      source ${./assert.sh}
+    ''
+    + command
+    + "touch $out"
+    );
+
+    wrappedHello = hello.overrideAttrs(oa: {
+      propagatedBuildInputs = [
+        wrapLua
+        lua.pkgs.cjson
+      ];
+      postFixup = ''
+        wrapLuaPrograms
+      '';
+    });
+in
+  pkgs.recurseIntoAttrs ({
+
+  checkAliases = runTest lua {
+    name = "check-aliases";
+    command = ''
+      generated=$(lua -e 'print(package.path)')
+      golden_LUA_PATH='./share/lua/${lua.luaversion}/?.lua;./?.lua;./?/init.lua'
+
+      assertStringEqual "$generated" "$golden_LUA_PATH"
+      '';
+  };
+
+  checkWrapping = pkgs.runCommandLocal "test-${lua.name}" ({
+    }) (''
+      grep -- 'LUA_PATH=' ${wrappedHello}/bin/hello
+      touch $out
+    '');
+
+})
+

pkgs/development/interpreters/lua-5/wrapper.nix

@@ -60,6 +60,8 @@ let
     passthru = lua.passthru // {
       interpreter = "${env}/bin/lua";
       inherit lua;
+      luaPath = lua.pkgs.lib.genLuaPathAbsStr env;
+      luaCpath = lua.pkgs.lib.genLuaCPathAbsStr env;
       env = stdenv.mkDerivation {
         name = "interactive-${lua.name}-environment";
         nativeBuildInputs = [ env ];