Add closure test

closures.js

@@ -0,0 +1,13 @@
+// const a = (x) => (y) => { return x + y; };
+
+function a(x) {
+  return function(y) {
+    return x + y;
+  }
+}
+
+const b = a(5);
+
+console.log(b(5))
+
+

nulascript/tests/eval_test.cc

@@ -8,7 +8,7 @@
 #include <string>
 #include <type_traits>
 
-// #define MULTILINE_STRING(s) #s
+#define MULTILINE_STRING(s) #s
 
 Storage* getEvaluatedStorage(std::string input) {
     Lexer l(input);
@@ -108,7 +108,19 @@ TEST(EvalSuite, TestFunction) {
     };
 
     std::vector<Test> tests = {
-        {"let something = fn(x) {x;}; something(69);", "69"}};
+        {"let something = fn(x) {x;}; something(69);", "69"},
+        {
+            // clang-format off
+            MULTILINE_STRING(
+                let something = fn(a) {
+                    fn(b) { a == b };
+                };
+
+                let result = something(10);
+                result(10);
+            ), "true"
+            // clang-format on
+        }};
 
     for (auto test : tests) {
         auto result = getEvaluatedStorage(test.input);