geek-calc/tests/unit/rpn.test.js

// Unit tests for RPN stack operations
// These tests should fail initially since the rpn-calculator module doesn't exist yet

function testRPNStackOperations() {
    try {
        // This will fail since rpn-calculator.js doesn't exist yet
        const rpnCalc = new RPNCalculator();
        
        // Test push operation
        rpnCalc.push(1);
        rpnCalc.push(2);
        rpnCalc.push(3);
        
        const stack = rpnCalc.getStack();
        if (stack.length !== 3 || stack[0] !== 1 || stack[1] !== 2 || stack[2] !== 3) {
            throw new Error('RPN push operation failed: stack does not contain expected values');
        }
        
        // Test pop operation
        const popped = rpnCalc.pop();
        if (popped !== 3) {
            throw new Error('RPN pop operation failed: did not return top value');
        }
        
        // Stack should now have 2 elements
        if (rpnCalc.getStack().length !== 2) {
            throw new Error('RPN pop operation failed: stack length incorrect after pop');
        }
        
        // Test multiple operations
        rpnCalc.clear();
        rpnCalc.push(4);
        rpnCalc.push(2);
        
        // Perform addition: 4 + 2 = 6
        const addResult = rpnCalc.operate('+');
        if (addResult !== 6) {
            throw new Error('RPN addition operation failed: 4 2 + should equal 6');
        }
        
        // Perform subtraction: 6 - 2 = 4 (the 2 was consumed, now 6-2)
        rpnCalc.push(2);
        const subResult = rpnCalc.operate('-');
        if (subResult !== 4) {
            throw new Error('RPN subtraction operation failed: 6 2 - should equal 4');
        }
        
        // Test multiplication
        rpnCalc.push(3);
        rpnCalc.push(4);
        const multResult = rpnCalc.operate('*');
        if (multResult !== 12) {
            throw new Error('RPN multiplication operation failed: 3 4 * should equal 12');
        }
        
        // Test division
        rpnCalc.push(12);
        rpnCalc.push(4);
        const divResult = rpnCalc.operate('/');
        if (divResult !== 3) {
            throw new Error('RPN division operation failed: 12 4 / should equal 3');
        }
        
        // Test division by zero
        rpnCalc.push(5);
        rpnCalc.push(0);
        const divByZeroResult = rpnCalc.operate('/');
        if (!isFinite(divByZeroResult)) {
            // This is expected behavior for division by zero in RPN
        } else {
            throw new Error('RPN division by zero should return Infinity');
        }
        
        // Test clear operation
        rpnCalc.push(10);
        rpnCalc.push(20);
        rpnCalc.clear();
        if (rpnCalc.getStack().length !== 0) {
            throw new Error('RPN clear operation failed: stack not empty after clear');
        }
        
        return true; // All tests passed
    } catch (error) {
        return { error: error.message };
    }
}

// Add test to global test collection
if (typeof addTest !== 'undefined') {
    addTest('RPN Stack Operations Unit Tests', testRPNStackOperations);
} else {
    console.log('Test harness not loaded. Run with test runner.');
}