test: Add tests for leading zero visual input handling

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

calculator/test.js

@@ -509,6 +509,34 @@ test('Number input chaos: leading zeros', () => {
   checkDisplay('7', 'Can input number with leading zeros after a clear');
 });
 
+test('Leading zeros are visually removed during input', () => {
+  press('0');
+  assert.strictEqual(global.last_display_num, '0', 'Input: 0');
+  press('0');
+  assert.strictEqual(global.last_display_num, '0', 'Second 0 should not create "00"');
+  press('7');
+  assert.strictEqual(global.last_display_num, '7', '0 should be replaced by 7');
+  press('R'); press('R');
+
+  press('0');
+  press('0');
+  press('.');
+  assert.strictEqual(global.last_display_num, '0.', 'Input: 00. -> "0."');
+  press('4');
+  assert.strictEqual(global.last_display_num, '0.4', 'Input: 00.4 -> "0.4"');
+  press('R'); press('R');
+
+  // After a calculation, starting a new number
+  press('1+2=');
+  checkDisplay(3);
+  press('0');
+  assert.strictEqual(global.last_display_num, '0', 'Post-calc: 0');
+  press('0');
+  assert.strictEqual(global.last_display_num, '0', 'Post-calc: 00 -> "0"');
+  press('5');
+  assert.strictEqual(global.last_display_num, '5', 'Post-calc: 005 -> "5"');
+});
+
 test('Repeated equals', () => {
   press('2+3=');
   checkDisplay('5');