ThoughtMCP

/** * Example Unit Test * * This example demonstrates TDD best practices with a simple calculator. * Follow this pattern for all unit tests. */ import { describe, it, expect, beforeEach } from "vitest"; // Simple calculator class for demonstration class Calculator { private result: number = 0; add(a: number, b: number): number { return a + b; } subtract(a: number, b: number): number { return a - b; } multiply(a: number, b: number): number { return a * b; } divide(a: number, b: number): number { if (b === 0) { throw new Error("Division by zero"); } return a / b; } setResult(value: number): void { this.result = value; } getResult(): number { return this.result; } clear(): void { this.result = 0; } } describe("Calculator", () => { let calculator: Calculator; beforeEach(() => { calculator = new Calculator(); }); describe("add", () => { it("should add two positive numbers", () => { const result = calculator.add(2, 3); expect(result).toBe(5); }); it("should add two negative numbers", () => { const result = calculator.add(-2, -3); expect(result).toBe(-5); }); it("should add positive and negative numbers", () => { const result = calculator.add(5, -3); expect(result).toBe(2); }); it("should handle zero", () => { const result = calculator.add(5, 0); expect(result).toBe(5); }); }); describe("subtract", () => { it("should subtract two positive numbers", () => { const result = calculator.subtract(5, 3); expect(result).toBe(2); }); it("should handle negative result", () => { const result = calculator.subtract(3, 5); expect(result).toBe(-2); }); }); describe("multiply", () => { it("should multiply two positive numbers", () => { const result = calculator.multiply(3, 4); expect(result).toBe(12); }); it("should handle zero", () => { const result = calculator.multiply(5, 0); expect(result).toBe(0); }); it("should handle negative numbers", () => { const result = calculator.multiply(-3, 4); expect(result).toBe(-12); }); }); describe("divide", () => { it("should divide two positive numbers", () => { const result = calculator.divide(10, 2); expect(result).toBe(5); }); it("should handle decimal results", () => { const result = calculator.divide(10, 3); expect(result).toBeCloseTo(3.333, 3); }); it("should throw error on division by zero", () => { expect(() => calculator.divide(10, 0)).toThrow("Division by zero"); }); }); describe("result management", () => { it("should set and get result", () => { calculator.setResult(42); expect(calculator.getResult()).toBe(42); }); it("should clear result", () => { calculator.setResult(42); calculator.clear(); expect(calculator.getResult()).toBe(0); }); it("should start with zero result", () => { expect(calculator.getResult()).toBe(0); }); }); }); /** * Key Takeaways: * * 1. Clear test organization with describe blocks * 2. One assertion per test (mostly) * 3. Descriptive test names * 4. Test normal cases and edge cases * 5. Test error conditions * 6. Use beforeEach for setup * 7. Tests are independent * 8. Fast execution */