tests/lib: Add basic unit tests for helpers.toLuaObject (#291)

tests/lib-tests.nix

@@ -0,0 +1,100 @@
+# For shorter test iterations run the following in the root of the repo:
+#   `echo ':b checks.${builtins.currentSystem}.lib-tests' | nix repl .`
+{
+  pkgs,
+  lib,
+}: let
+  helpers = import ../lib/helpers.nix {inherit pkgs lib;};
+  results = pkgs.lib.runTests {
+    testToLuaObject = {
+      expr = helpers.toLuaObject {
+        foo = "bar";
+        qux = [1 2 3];
+      };
+      expected = ''{["foo"] = "bar",["qux"] = {1,2,3}}'';
+    };
+
+    testToLuaObjectRawLua = {
+      expr = helpers.toLuaObject {
+        __raw = "<lua code>";
+      };
+      expected = "<lua code>";
+    };
+
+    testToLuaObjectLuaTableMixingList = {
+      expr = helpers.toLuaObject {
+        "@...." = "foo";
+        bar = "baz";
+      };
+      expected = ''{"foo",["bar"] = "baz"}'';
+    };
+
+    testToLuaObjectNestedAttrs = {
+      expr = helpers.toLuaObject {
+        a = {
+          b = 1;
+          c = 2;
+          d = {e = 3;};
+        };
+      };
+      expected = ''{["a"] = {["b"] = 1,["c"] = 2,["d"] = {["e"] = 3}}}'';
+    };
+
+    testToLuaObjectNestedList = {
+      expr = helpers.toLuaObject [1 2 [3 4 [5 6]] 7];
+      expected = "{1,2,{3,4,{5,6}},7}";
+    };
+
+    testToLuaObjectNonStringPrims = {
+      expr = helpers.toLuaObject {
+        a = 1.0;
+        b = 2;
+        c = true;
+        d = false;
+        e = null;
+      };
+      expected = ''{["a"] = 1.000000,["b"] = 2,["c"] = true,["d"] = false}'';
+    };
+
+    testToLuaObjectNilPrim = {
+      expr = helpers.toLuaObject null;
+      expected = "nil";
+    };
+
+    testToLuaObjectStringPrim = {
+      expr = helpers.toLuaObject ''
+        foo\bar
+        baz'';
+      expected = ''"foo\\bar\nbaz"'';
+    };
+
+    testToLuaObjectShouldFilterNullAttrs = {
+      expr = helpers.toLuaObject {
+        a = null;
+        b = {};
+        c = [];
+        d = {
+          e = null;
+          f = {};
+        };
+      };
+      expected = ''{["b"] = {},["c"] = {},["d"] = {["f"] = {}}}'';
+    };
+  };
+in
+  if results == []
+  then pkgs.runCommand "lib-tests-success" {} "touch $out"
+  else
+    pkgs.runCommand "lib-tests-failure" {
+      results = pkgs.lib.concatStringsSep "\n" (
+        builtins.map (result: ''
+          ${result.name}:
+            expected: ${result.expected}
+            result: ${result.result}
+        '')
+        results
+      );
+    } ''
+      echo -e "Tests failed:\\n\\n$results" >&2
+      exit 1
+    ''