cpp-test

C++ TDD Command

This command enforces test-driven development methodology for C++ code using GoogleTest/GoogleMock with CMake/CTest.

What This Command Does

1. Define Interfaces: Scaffold class/function signatures first
2. Write Tests: Create comprehensive GoogleTest test cases (RED)
3. Run Tests: Verify tests fail for the right reason
4. Implement Code: Write minimal code to pass (GREEN)
5. Refactor: Improve while keeping tests green
6. Check Coverage: Ensure 80%+ coverage

When to Use

Use /cpp-test when:

• Implementing new C++ functions or classes
• Adding test coverage to existing code
• Fixing bugs (write failing test first)
• Building critical business logic
• Learning TDD workflow in C++

TDD Cycle

RED     → Write failing GoogleTest test
GREEN   → Implement minimal code to pass
REFACTOR → Improve code, tests stay green
REPEAT  → Next test case

Example Session

User: /cpp-test I need a function to validate email addresses

Agent:
# TDD Session: Email Validator

## Step 1: Define Interface

```cpp
// validator/email.hpp
#pragma once
#include <string>
#include <expected>

enum class EmailError {
    Empty,
    InvalidFormat
};

std::expected<void, EmailError> validate_email(const std::string& email);
```

## Step 2: Write Tests (RED)

```cpp
// validator/email_test.cpp
#include <gtest/gtest.h>
#include "email.hpp"

TEST(ValidateEmail, AcceptsSimpleEmail) {
    auto result = validate_email("[email protected]");
    EXPECT_TRUE(result.has_value());
}

TEST(ValidateEmail, AcceptsSubdomain) {
    EXPECT_TRUE(validate_email("[email protected]").has_value());
}

TEST(ValidateEmail, AcceptsPlus) {
    EXPECT_TRUE(validate_email("[email protected]").has_value());
}

TEST(ValidateEmail, RejectsEmpty) {
    auto result = validate_email("");
    ASSERT_FALSE(result.has_value());
    EXPECT_EQ(result.error(), EmailError::Empty);
}

TEST(ValidateEmail, RejectsNoAtSign) {
    EXPECT_FALSE(validate_email("userexample.com").has_value());
}