Make #CALL raise an error if the return value is not a string

skoolkit/skoolmacro.py

@@ -1,4 +1,4 @@
-# Copyright 2012-2024 Richard Dymond (rjdymond@gmail.com)
+# Copyright 2012-2025 Richard Dymond (rjdymond@gmail.com)
 #
 # This file is part of SkoolKit.
 #
@@ -780,6 +780,8 @@ def parse_call(writer, text, index, *cwd):
         raise MacroParsingError(f"{ftype} call {text[index + 1:p_end]} failed: {e}")
     if retval is None:
         retval = ''
+    if not isinstance(retval, str):
+        raise MacroParsingError(f"Return value from {text[index + 1:p_end]} is not a string")
     return end, retval
 
 def parse_chr(writer, text, index, *cwd):

tests/macrotest.py

@@ -166,6 +166,11 @@ def test_macro_call_with_nonexistent_method(self):
             self.assertEqual(writer.expand(macro), '')
             self.assertEqual(self.err.getvalue().split('\n')[0], f'WARNING: Unknown method name in #CALL macro: {method_name}')
 
+    def test_macro_call_with_return_value_that_is_not_a_string(self):
+        writer = self._get_writer()
+        writer.test_call = self._test_call_retval_not_string
+        self._assert_error(writer, '#CALL(test_call())', 'Return value from test_call() is not a string', ERROR_PREFIX.format('CALL'))
+
     def test_macro_call_invalid(self):
         writer = self._get_writer()
         writer.test_call = self._test_call

tests/test_skoolasm.py

@@ -130,6 +130,9 @@ def _test_call_no_retval(self, *args):
     def _test_call_no_args(self):
         return 'OK'
 
+    def _test_call_retval_not_string(self):
+        return 1
+
     def test_macros_are_expanded(self):
         skool = """
             @start

tests/test_skoolhtml.py

@@ -1540,6 +1540,9 @@ def _test_call_no_retval(self, *args):
     def _test_call_no_args(self, cwd):
         return 'OK'
 
+    def _test_call_retval_not_string(self, cwd):
+        return 1
+
     def _unsupported_macro(self, *args):
         raise UnsupportedMacroError()