Add assert function to stdlib. Useful for tests

src/error.hpp

@@ -17,6 +17,7 @@ enum class ErrorCode {
   ArgumentCountMismatch,
   IOError,
   Interrupt,
+  AssertionFailed,
 };
 
 void seterr(const char* err);

src/stdlib.cpp

@@ -53,6 +53,17 @@ Result<Value> stdlib_println(const Array& params) {
 
 Result<Value> stdlib_prn(const Array& params) { return ERROR(NotImplemented); }
 
+Result<Value> stdlib_assert(const Array& params) {
+  for (uint64_t i = 0; i < params.size(); i++) {
+    Value param = TRY(params.get(i));
+    if (!param.is<Bool>()) return ERROR(AssertionFailed);
+    auto v = param.to<Bool>()->value();
+    if (!v) return ERROR(AssertionFailed);
+  }
+
+  return Value(TRY(Nil::create()));
+}
+
 #define STDLIB_FUNCTION(name, id)                                  \
   [(uint64_t)StdlibFunctionId::id] = {#name, StdlibFunctionId::id, \
                                       stdlib_##name}
@@ -62,6 +73,7 @@ static StdlibFunctionEntry function_entries[] = {
     STDLIB_FUNCTION(print, Print),
     STDLIB_FUNCTION(println, PrintLn),
     STDLIB_FUNCTION(prn, Prn),
+    STDLIB_FUNCTION(assert, Assert),
     [(uint64_t)StdlibFunctionId::Max] = {0, StdlibFunctionId::Max,
                                          stdlib_unknown},
 };

src/stdlib.hpp

@@ -9,6 +9,7 @@ enum class StdlibFunctionId : uint64_t {
   Print,
   PrintLn,
   Prn,
+  Assert,
   Max,
 };