1867 - keep tests from corrupting lesson/ directory

1 files changed, 4 insertions, 1 deletions

diff --git a/029tools.cc b/029tools.cc
index 45d6a20a..8285969e 100644
--- a/029tools.cc
+++ b/029tools.cc
@@ -186,8 +186,11 @@ case _SYSTEM: {
     raise << current_recipe_name() << ": '$system' requires exactly one ingredient, but got none\n" << end();
     break;
   }
-  int status = system(current_instruction().ingredients.at(0).name.c_str());
   products.resize(1);
+  // ignore 'system' calls in tests since anything we do with them is by
+  // definition impossible to test through mu.
+  if (Current_scenario) break;
+  int status = system(current_instruction().ingredients.at(0).name.c_str());
   products.at(0).push_back(status);
   break;
 }