Add README.md

app/convert_currency.go

@@ -1,9 +1,11 @@
 package app
 
 import (
+	"context"
 	"converter/domain"
 	"converter/infrastructure/coinmarketcap"
 	"fmt"
+	"strings"
 
 	"github.com/shopspring/decimal"
 )
@@ -17,7 +19,7 @@ const (
 // Note: The returned RateDTO may contain a reversed rate (e.g., if requesting USD->BTC
 // but only BTC->USD is available), indicated by FromCode/ToCode being swapped from the request
 type RateProvider interface {
-	GetRate(fromCode, toCode string) (coinmarketcap.RateDTO, error)
+	GetRate(ctx context.Context, fromCode, toCode string) (coinmarketcap.RateDTO, error)
 }
 
 // ConvertCurrencyUseCase handles currency conversion operations
@@ -35,7 +37,11 @@ func NewConvertCurrencyUseCase(rateProvider RateProvider, converter *domain.Curr
 }
 
 // Execute performs currency conversion
-func (uc *ConvertCurrencyUseCase) Execute(amount, fromCode, toCode string) (domain.Money, error) {
+func (uc *ConvertCurrencyUseCase) Execute(ctx context.Context, amount, fromCode, toCode string) (domain.Money, error) {
+	// Normalize currency codes to uppercase for consistency
+	fromCode = strings.ToUpper(strings.TrimSpace(fromCode))
+	toCode = strings.ToUpper(strings.TrimSpace(toCode))
+
 	// Create currencies with uniform precision
 	fromCurrency, err := domain.NewCurrency(fromCode, fromCode, CurrencyPrecision)
 	if err != nil {
@@ -49,7 +55,7 @@ func (uc *ConvertCurrencyUseCase) Execute(amount, fromCode, toCode string) (doma
 	}
 
 	// Get exchange rate DTO from provider
-	rateDTO, err := uc.rateProvider.GetRate(fromCode, toCode)
+	rateDTO, err := uc.rateProvider.GetRate(ctx, fromCode, toCode)
 	if err != nil {
 		return domain.Money{}, err
 	}

app/convert_currency_test.go

@@ -1,12 +1,14 @@
 package app
 
 import (
+	"context"
 	"converter/app/mocks"
 	"converter/domain"
 	"converter/infrastructure/coinmarketcap"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/mock"
 )
 
 func TestConvertCurrencyUseCase_Execute(t *testing.T) {
@@ -36,7 +38,7 @@ func TestConvertCurrencyUseCase_Execute(t *testing.T) {
 					Price:    50000.0,   // BTC price in USD
 					Source:   "coinmarketcap",
 				}
-				m.On("GetRate", "BTC", "USD").Return(rateDTO, nil)
+				m.On("GetRate", mock.Anything, "BTC", "USD").Return(rateDTO, nil)
 			},
 		},
 		{
@@ -56,7 +58,7 @@ func TestConvertCurrencyUseCase_Execute(t *testing.T) {
 					Price:    50000.0,   // BTC price in USD (will be inverted)
 					Source:   "coinmarketcap",
 				}
-				m.On("GetRate", "USD", "BTC").Return(rateDTO, nil)
+				m.On("GetRate", mock.Anything, "USD", "BTC").Return(rateDTO, nil)
 			},
 		},
 		{
@@ -89,7 +91,7 @@ func TestConvertCurrencyUseCase_Execute(t *testing.T) {
 			wantCode: "",
 			wantErr:  true,
 			setupMock: func(m *mocks.RateProvider) {
-				m.On("GetRate", "XYZ", "ABC").Return(coinmarketcap.RateDTO{}, domain.ErrRateNotFound)
+				m.On("GetRate", mock.Anything, "XYZ", "ABC").Return(coinmarketcap.RateDTO{}, domain.ErrRateNotFound)
 			},
 		},
 		{
@@ -100,7 +102,7 @@ func TestConvertCurrencyUseCase_Execute(t *testing.T) {
 			wantCode: "",
 			wantErr:  true,
 			setupMock: func(m *mocks.RateProvider) {
-				m.On("GetRate", "USD", "INVALID").Return(coinmarketcap.RateDTO{}, domain.ErrUnsupportedCurrency)
+				m.On("GetRate", mock.Anything, "USD", "INVALID").Return(coinmarketcap.RateDTO{}, domain.ErrUnsupportedCurrency)
 			},
 		},
 		{
@@ -127,7 +129,7 @@ func TestConvertCurrencyUseCase_Execute(t *testing.T) {
 			tt.setupMock(mockProvider)
 
 			// Execute
-			result, err := useCase.Execute(tt.amount, tt.fromCode, tt.toCode)
+			result, err := useCase.Execute(context.Background(), tt.amount, tt.fromCode, tt.toCode)
 
 			// Assert error expectations
 			if tt.wantErr {

app/mocks/RateProvider.go

@@ -3,6 +3,7 @@
 package mocks
 
 import (
+	context "context"
 	coinmarketcap "converter/infrastructure/coinmarketcap"
 
 	mock "github.com/stretchr/testify/mock"
@@ -13,9 +14,9 @@ type RateProvider struct {
 	mock.Mock
 }
 
-// GetRate provides a mock function with given fields: fromCode, toCode
+// GetRate provides a mock function with given fields: ctx, fromCode, toCode
-func (_m *RateProvider) GetRate(fromCode string, toCode string) (coinmarketcap.RateDTO, error) {
+func (_m *RateProvider) GetRate(ctx context.Context, fromCode string, toCode string) (coinmarketcap.RateDTO, error) {
-	ret := _m.Called(fromCode, toCode)
+	ret := _m.Called(ctx, fromCode, toCode)
 
 	if len(ret) == 0 {
 		panic("no return value specified for GetRate")
@@ -23,17 +24,17 @@ func (_m *RateProvider) GetRate(fromCode string, toCode string) (coinmarketcap.R
 
 	var r0 coinmarketcap.RateDTO
 	var r1 error
-	if rf, ok := ret.Get(0).(func(string, string) (coinmarketcap.RateDTO, error)); ok {
+	if rf, ok := ret.Get(0).(func(context.Context, string, string) (coinmarketcap.RateDTO, error)); ok {
-		return rf(fromCode, toCode)
+		return rf(ctx, fromCode, toCode)
 	}
-	if rf, ok := ret.Get(0).(func(string, string) coinmarketcap.RateDTO); ok {
+	if rf, ok := ret.Get(0).(func(context.Context, string, string) coinmarketcap.RateDTO); ok {
-		r0 = rf(fromCode, toCode)
+		r0 = rf(ctx, fromCode, toCode)
 	} else {
 		r0 = ret.Get(0).(coinmarketcap.RateDTO)
 	}
 
-	if rf, ok := ret.Get(1).(func(string, string) error); ok {
+	if rf, ok := ret.Get(1).(func(context.Context, string, string) error); ok {
-		r1 = rf(fromCode, toCode)
+		r1 = rf(ctx, fromCode, toCode)
 	} else {
 		r1 = ret.Error(1)
 	}

cmd/converter/main.go

@@ -1,11 +1,15 @@
 package main
 
 import (
+	"context"
 	"converter/app"
 	"converter/domain"
 	"converter/infrastructure/coinmarketcap"
 	"fmt"
 	"os"
+	"os/signal"
+	"syscall"
+	"time"
 )
 
 const (
@@ -40,8 +44,22 @@ func main() {
 	converter := domain.NewCurrencyConverter()
 	useCase := app.NewConvertCurrencyUseCase(client, converter)
 
+	// Create context with timeout and signal handling
+	ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
+	defer cancel()
+
+	// Set up graceful shutdown on interrupt signals
+	sigChan := make(chan os.Signal, 1)
+	signal.Notify(sigChan, syscall.SIGINT, syscall.SIGTERM)
+
+	go func() {
+		<-sigChan
+		fmt.Fprintf(os.Stderr, "\nReceived interrupt signal, shutting down...\n")
+		cancel()
+	}()
+
 	// Execute conversion
-	result, err := useCase.Execute(amount, fromCurrency, toCurrency)
+	result, err := useCase.Execute(ctx, amount, fromCurrency, toCurrency)
 	if err != nil {
 		fmt.Fprintf(os.Stderr, "Error: %v\n", err)
 		os.Exit(1)
@@ -49,4 +67,4 @@ func main() {
 
 	// Output result
 	fmt.Printf("%s %s\n", result.Amount.StringFixed(8), result.Currency.Code)
-}
+}

infrastructure/coinmarketcap/client.go

@@ -1,6 +1,7 @@
 package coinmarketcap
 
 import (
+	"context"
 	"errors"
 	"fmt"
 
@@ -40,16 +41,16 @@ func NewClient(apiKey string) *Client {
 }
 
 // GetRate fetches exchange rate from CoinMarketCap API
-func (c *Client) GetRate(fromCode, toCode string) (RateDTO, error) {
+func (c *Client) GetRate(ctx context.Context, fromCode, toCode string) (RateDTO, error) {
 	// Try direct conversion first
-	rateDTO, err := c.tryGetRate(fromCode, toCode)
+	rateDTO, err := c.tryGetRate(ctx, fromCode, toCode)
 	if err == nil {
 		return rateDTO, nil
 	}
 
 	// If empty result but no other error, try reverse
 	if err == ErrUnknownSymbol {
-		reverseDTO, reverseErr := c.tryGetRate(toCode, fromCode)
+		reverseDTO, reverseErr := c.tryGetRate(ctx, toCode, fromCode)
 		if reverseErr == nil {
 			return reverseDTO, nil
 		}
@@ -69,11 +70,12 @@ func (c *Client) GetRate(fromCode, toCode string) (RateDTO, error) {
 }
 
 // tryGetRate attempts to get rate in specified direction
-func (c *Client) tryGetRate(fromCode, toCode string) (RateDTO, error) {
+func (c *Client) tryGetRate(ctx context.Context, fromCode, toCode string) (RateDTO, error) {
 	var response APIResponse
 
 	// Make API request
 	resp, err := c.httpClient.R().
+		SetContext(ctx).
 		SetQueryParam("symbol", fromCode).
 		SetQueryParam("convert", toCode).
 		SetResult(&response).