# Test Compatibility Kit (TCK) for Storage Implementations

The Test Compatibility Kit (TCK) is a standardized test suite for validating storage implementations in the Fiber Storage repository. It provides a comprehensive set of tests that ensure all storage backends behave consistently and correctly implement the `storage.Storage` interface.

## Overview

The TCK leverages [testify/suite](https://github.com/stretchr/testify#suite-package) to provide a structured testing approach with setup/teardown hooks and consistent test execution. It automatically tests all core storage operations including:

- Basic CRUD operations (Set, Get, Delete)
- Context-aware operations (SetWithContext, GetWithContext, etc.)
- TTL (Time-To-Live) functionality
- Storage reset and cleanup
- Connection handling for stores that implement `StorageWithConn`

## Why Use the TCK?

- **Consistency**: Ensures all storage implementations behave identically
- **Completeness**: Tests all required storage interface methods
- **Maintenance**: Reduces test code duplication across storage implementations
- **Quality**: Provides comprehensive edge case and error condition testing
- **Integration**: Works seamlessly with testcontainers for isolated testing

## Core Concepts

### TCKSuite Interface

To use the TCK, you must implement the `TCKSuite` interface:

```go
// TCKSuite is the interface that must be implemented by the test suite.
// It defines how to create a new store with a container.
// The generic parameters are the storage type, the driver type returned by the Conn method,
// and the container type used to back the storage.
//
// IMPORTANT: The container type must exist as a Testcontainers module.
// Please refer to the [testcontainers] package for more information.
type TCKSuite[T storage.Storage, D any, C testcontainers.Container] interface {
	// NewStore is a function that returns a new store.
	// It is called by the [New] function to create a new store.
	NewStore() func(ctx context.Context, tb testing.TB, ctr C) (T, error)

	// NewContainer is a function that returns a new container.
	// It is called by the [New] function to create a new container.
	NewContainer() func(ctx context.Context, tb testing.TB) (C, error)
}
```

**Generic Parameters:**
- `T`: Your concrete storage type (e.g., `*mysql.Storage`)
- `D`: The driver type returned by `Conn()` method (e.g., `*sql.DB`)
- `C`: The testcontainer type (e.g., `*mysql.MySQLContainer`)

Please verify that a suitable Testcontainers module exists for your container type. See the [Testcontainers modules catalog](https://testcontainers.com/modules/?language=go) for details.

### Test Execution Modes

The TCK supports two execution modes:

- **PerTest** (default): Creates a new container and storage instance for each test
- **PerSuite**: Creates one container and storage instance for the entire test suite

## Implementation Guide: Example

Here's how to implement TCK tests for a new storage backend:

### Step 1: Define Your TCK Implementation

```go
// ExampleStorageTCK is the test suite for the Example storage.
type ExampleStorageTCK struct{}

// NewStore is a function that returns a new Example storage.
// It implements the [tck.TCKSuite] interface, allowing the TCK to create a new Example storage
// from the container created by the TCK.
func (s *ExampleStorageTCK) NewStore() func(ctx context.Context, tb testing.TB, ctr *ExampleContainer) (*Storage, error) {
    return func(ctx context.Context, tb testing.TB, ctr *example.Container) (*Storage, error) {
        // Use container APIs to get connection details
        conn, err := ctr.ConnectionString(ctx)
        require.NoError(tb, err)

        store := New(Config{
            // Apply the storage-specific configuration
            ConnectionURI: conn,
            Reset:         true,
        })

        return store, nil
    }
}

// NewContainer is a function that returns a new Example container.
// It implements the [tck.TCKSuite] interface, allowing the TCK to create a new Example container
// for the Example storage.
func (s *ExampleStorageTCK) NewContainer() func(ctx context.Context, tb testing.TB) (*example.Container, error) {
    return func(ctx context.Context, tb testing.TB) (*example.Container, error) {
        return mustStartExample(tb), nil
    }
}
```

### Step 2: Implement Container Creation

Create a helper function to start your storage backend's container:

```go
func mustStartExample(t testing.TB) *example.Container {
    img := exampleImage
    if imgFromEnv := os.Getenv(exampleImageEnvVar); imgFromEnv != "" {
        img = imgFromEnv
    }

    ctx := context.Background()

    c, err := example.Run(ctx, img,
        example.WithOptionA("valueA"),
        example.WithOptionB("valueB"),
        testcontainers.WithWaitStrategy(
            wait.ForListeningPort("examplePort/tcp"),
        ),
    )
    testcontainers.CleanupContainer(t, c)
    require.NoError(t, err)

    return c
}
```

### Step 3: Create and Run the TCK Test

```go
func TestExampleStorageTCK(t *testing.T) {
    // Create the TCK suite with proper generic type parameters
    s, err := tck.New[*ExampleStorage, *ExampleDriver, *ExampleContainer](
        context.Background(), 
        t, 
        &ExampleStorageTCK{}, 
        tck.PerTest(), // or tck.PerSuite() for suite-level containers
    )
    require.NoError(t, err)

    // Run all TCK tests
    suite.Run(t, s)
}
```

## Key Implementation Guidelines

### 1. Generic Type Parameters

When calling `tck.New`, specify the correct type parameters:
- `T`: Your storage pointer type (e.g., `*Storage`)
- `D`: The driver type returned by `Conn()` (or `any` if not applicable)
- `C`: The container type returned by `NewContainer()`

### 2. Error Handling

Always use `require.NoError(tb, err)` in your factory functions to ensure test failures are properly reported.

### 3. Container Cleanup

The TCK handles container cleanup, but ensure your `mustStart*` helpers call `testcontainers.CleanupContainer(t, container)`. For ad‑hoc tests outside the TCK, call `CleanupContainer` to avoid leaving containers running until the test process exits. Although Ryuk will prune them, it’s better to clean up immediately.

### 4. Configuration

Configure your storage with appropriate test settings:
- Enable `Reset: true` if your storage supports it
- Use test-specific database/namespace names
- Configure appropriate timeouts and connection limits

### 5. Context Handling

Always respect the provided `context.Context` in your factory functions, especially for container startup and storage initialization.

## Testing Different Scenarios

### PerTest Mode (Recommended)
Use when you need complete isolation between tests:

```go
s, err := tck.New[*Storage, *sql.DB](ctx, t, &ExampleStorageTCK{}, tck.PerTest())
```

**Pros:**
- Complete test isolation
- No cross-test contamination
- Easier debugging of individual test failures

**Cons:**
- Slower execution due to container startup overhead
- Higher resource usage, although mitigated by Testcontainers' cleanup mechanism

### PerSuite Mode
Use when container startup is expensive and tests can share state:

```go
s, err := tck.New[*Storage, *sql.DB](ctx, t, &ExampleStorageTCK{}, tck.PerSuite())
```

**Pros:**
- Faster execution
- Lower resource usage

**Cons:**
- Tests may affect each other
- Requires careful state management

## Troubleshooting

### Common Issues

1. **Wrong Generic Types**: Ensure type parameters match your actual storage and driver types
2. **Container Startup Failures**: Check wait strategies and ensure proper service readiness
3. **Connection Issues**: Verify connection strings and authentication in your `NewStore()` implementation
4. **Test Isolation**: If tests interfere with each other, consider switching from `PerSuite` to `PerTest`

### Best Practices

- Use environment variables for container image versions
- Implement proper wait strategies for container readiness
- Include cleanup calls even though TCK handles them automatically
- Test your TCK implementation with both `PerTest` and `PerSuite` modes
- Use meaningful test data that won't conflict across parallel test runs

## Complete Example Template

Here's a complete template for implementing TCK tests for a new storage backend:

```go
package newstorage

import (
    "context"
    "os"
    "testing"
    
    "github.com/gofiber/storage/testhelpers/tck"
    "github.com/stretchr/testify/require"
    "github.com/stretchr/testify/suite"
    "github.com/testcontainers/testcontainers-go"
    // Import your specific testcontainer module
)

const (
    defaultImage = "your-storage-image:latest"
    imageEnvVar  = "TEST_YOUR_STORAGE_IMAGE"
)

type YourStorageTCK struct{}

func (s *YourStorageTCK) NewStore() func(ctx context.Context, tb testing.TB, ctr *YourContainer) (*Storage, error) {
    return func(ctx context.Context, tb testing.TB, ctr *YourContainer) (*Storage, error) {
        // Get connection details from container
        conn, err := ctr.ConnectionString(ctx)
        require.NoError(tb, err)

        // Create and configure your storage
        store := New(Config{
            ConnectionURI: conn,
            Reset:         true,
            // Add other test-specific configuration
        })

        return store, nil
    }
}

func (s *YourStorageTCK) NewContainer() func(ctx context.Context, tb testing.TB) (*YourContainer, error) {
    return func(ctx context.Context, tb testing.TB) (*YourContainer, error) {
        return mustStartYourStorage(tb), nil
    }
}

func mustStartYourStorage(t testing.TB) *YourContainer {
    img := defaultImage
    if imgFromEnv := os.Getenv(imageEnvVar); imgFromEnv != "" {
        img = imgFromEnv
    }

    ctx := context.Background()

    c, err := yourstorage.Run(ctx, img,
        // Add your storage-specific configuration
        testcontainers.WithWaitStrategy(
            // Add appropriate wait strategies
        ),
    )
    testcontainers.CleanupContainer(t, c)
    require.NoError(t, err)

    return c
}

func TestYourStorageTCK(t *testing.T) {
    s, err := tck.New[*Storage, YourDriverType, *YourContainer](
        context.Background(),
        t,
        &YourStorageTCK{},
        tck.PerTest(),
    )
    require.NoError(t, err)

    suite.Run(t, s)
}
```

This template provides a solid foundation for implementing TCK tests for any new storage backend in the Fiber Storage repository.