test: Expand Pi button test coverage

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

calculator/test.js

@@ -517,5 +517,73 @@ test('Operation with Pi', () => {
   checkDisplay(5 * Math.PI);
 });
 
+test('Pi as second operand', () => {
+  press('2+p=');
+  checkDisplay(2 + Math.PI);
+});
+
+test('Chaining operations with Pi', () => {
+  press('p*2+3=');
+  checkDisplay(Math.PI * 2 + 3);
+});
+
+test('Unary operations on Pi', () => {
+  press('p');
+  checkDisplay(Math.PI);
+  press('r'); // sqrt
+  checkDisplay(Math.sqrt(Math.PI));
+  press('R'); press('R'); // AC
+  press('p');
+  press('s'); // x^2
+  checkDisplay(Math.PI * Math.PI);
+  press('R'); press('R'); // AC
+  press('p');
+  press('i'); // 1/x
+  checkDisplay(1 / Math.PI);
+});
+
+test('Trig functions with Pi (rad)', () => {
+  buttonPress('angleMode'); // switch to RAD
+  assert.strictEqual(scientificOperators.angleMode.val, 'rad');
+
+  press('p');
+  press('sin');
+  checkDisplay(Math.sin(Math.PI)); // ~0
+  press('R'); press('R');
+
+  press('p');
+  press('cos');
+  checkDisplay(Math.cos(Math.PI)); // -1
+  press('R'); press('R');
+
+  press('p');
+  press('tan');
+  checkDisplay(Math.tan(Math.PI)); // ~0
+
+  buttonPress('angleMode'); // switch back to DEG
+  assert.strictEqual(scientificOperators.angleMode.val, 'deg');
+});
+
+test('Pi after equals', () => {
+  press('1+2=');
+  checkDisplay(3);
+  press('p');
+  checkDisplay(Math.PI);
+  press('+1=');
+  checkDisplay(Math.PI + 1);
+});
+
+test('Pi with negative operator', () => {
+  press('pN');
+  checkDisplay(-Math.PI);
+  press('*2=');
+  checkDisplay(-Math.PI * 2);
+});
+
+test('Negative number times Pi', () => {
+  press('2N*p=');
+  checkDisplay(-2 * Math.PI);
+});
+
 // Run all the defined tests
 runTests();