Add unit test for single

single/main_test.go

@@ -0,0 +1,64 @@
+package main
+
+import (
+	"sync"
+	"testing"
+)
+
+func TestProcessTransaction(t *testing.T) {
+	// Setup accounts
+	accounts := map[string]*Account{
+		"11111": {AccountNumber: "11111", Balance: 10000},
+		"22222": {AccountNumber: "22222", Balance: 20000},
+	}
+
+	// List of transactions
+	transactions := []Transaction{
+		{"11111", -200},  // Debit
+		{"11111", 300},   // Credit
+		{"22222", -500},  // Debit
+		{"22222", -3000}, // Insufficient funds
+		{"11111", 100},   // Credit
+	}
+
+	// Expected final balances
+	expectedBalances := map[string]float64{
+		"11111": 10200,
+		"22222": 16500,
+	}
+
+	var wg sync.WaitGroup
+
+	// Process transactions concurrently
+	for _, tr := range transactions {
+		tr := tr // Capture range variable for goroutine
+		account, exists := accounts[tr.AccountNumber]
+		if !exists {
+			t.Errorf("Account %s not found", tr.AccountNumber)
+			continue
+		}
+
+		wg.Add(1)
+		go func(acc *Account, amount float64) {
+			defer wg.Done() // Ensure Done is called even if ProcessTransaction fails
+			acc.mu.Lock()
+			if amount < 0 && acc.Balance+amount < 0 {
+				acc.mu.Unlock()
+				t.Errorf("Insufficient funds for account %s", acc.AccountNumber)
+				return
+			}
+			acc.Balance += amount
+			acc.mu.Unlock()
+		}(account, tr.Amount)
+	}
+
+	wg.Wait() // Wait for all transactions to complete
+
+	// Verify final balances
+	for accountNumber, account := range accounts {
+		if account.Balance != expectedBalances[accountNumber] {
+			t.Errorf("Account %s: expected balance %.2f, got %.2f",
+				account.AccountNumber, expectedBalances[accountNumber], account.Balance)
+		}
+	}
+}