fix: Expose buttonPress function for testing

Co-authored-by: aider (gemini/gemini-2.5-pro) <aider@aider.chat>

calculator/test.js

@@ -57,10 +57,12 @@ global.load = () => {};
 
 
 // --- Load calculator app ---
+// We wrap the app code in a function that returns the buttonPress function,
+// so we can capture it and use it in our tests.
 const calculatorCode = fs.readFileSync(path.join(__dirname, 'calculator.app.js'), 'utf8');
-(function(require) {
+const wrappedCode = `(function(require) { ${calculatorCode}; return buttonPress; })`;
-  eval(calculatorCode);
+const getButtonPress = eval(wrappedCode);
-})((name) => {
+const buttonPress = getButtonPress((name) => {
   if (name === "FontDylex7x13") {
     return { add: () => {} };
   }