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Testing React Calculator Component Operations in cover-agent

This test suite validates core functionality of a React calculator component using Jest and Enzyme. It focuses on mathematical operations, state management, and error handling through comprehensive unit tests.

Test Coverage Overview

The test suite provides thorough coverage of calculator operations and state management.

Basic mathematical operations including exponentiation and modulus
Clear functionality across multiple state properties
Error handling for invalid operators
State reset verification

Implementation Analysis

The testing approach utilizes shallow rendering with Enzyme for React component testing. It implements a beforeEach setup pattern for consistent test initialization.

Instance method testing for operation handling
State verification after operations
Isolated component testing using shallow rendering
Systematic state management validation

Technical Details

Jest as the primary testing framework
Enzyme for React component testing
Shallow rendering for component isolation
Instance() method access for direct component interaction
State assertions using expect().toBe()
Error handling validation using expect().toThrow()

Best Practices Demonstrated

The test suite exemplifies strong testing practices with clear organization and comprehensive coverage.

Consistent test setup using beforeEach
Isolated test cases for each functionality
Thorough state verification
Error case handling
Clear test descriptions
Systematic component state reset verification

codium-ai/cover-agent

templated_tests/react_calculator/src/tests/Calculator.test.js

            
import React from 'react';
import { shallow } from 'enzyme';
import Calculator from '../modules/Calculator'; 

describe('Calculator Component', () => {
    let wrapper;
    beforeEach(() => {
        wrapper = shallow(<Calculator />);
    });

    test('correctly calculates exponentiation', () => {
        wrapper.instance().handleInput('2');
        wrapper.instance().handleOperation('**');
        wrapper.instance().handleInput('3');
        wrapper.instance().handleEquals();
        expect(wrapper.state('onDisplay')).toBe('8');
    });

    test('correctly calculates modulus', () => {
        wrapper.instance().handleInput('10');
        wrapper.instance().handleOperation('%');
        wrapper.instance().handleInput('3');
        wrapper.instance().handleEquals();
        expect(wrapper.state('onDisplay')).toBe('1');
    });

    test('resets display to 0 on clear', () => {
        wrapper.instance().handleInput('123');
        wrapper.instance().handleClear();
        expect(wrapper.state('onDisplay')).toBe('0');
    });

    test('resets currentTotal to 0 on clear', () => {
        wrapper.instance().handleInput('123');
        wrapper.instance().handleOperation('+');
        wrapper.instance().handleInput('456');
        wrapper.instance().handleEquals();
        wrapper.instance().handleClear();
        expect(wrapper.state('currentTotal')).toBe(0);
    });

    test('resets currentOperator to null on clear', () => {
        wrapper.instance().handleInput('123');
        wrapper.instance().handleOperation('+');
        wrapper.instance().handleClear();
        expect(wrapper.state('currentOperator')).toBeNull();
    });

    test('resets lastActionEquals to false on clear', () => {
        wrapper.instance().handleInput('123');
        wrapper.instance().handleOperation('+');
        wrapper.instance().handleInput('456');
        wrapper.instance().handleEquals();
        wrapper.instance().handleClear();
        expect(wrapper.state('lastActionEquals')).toBe(false);
    });

    test('throws error for invalid operator', () => {
        expect(() => {
            wrapper.instance().evaluate('5', '3', 'invalid_operator');
        }).toThrow("Invalid operator");
    });
});