From 4716b5105f6d051df004c2b473abab37738a954a Mon Sep 17 00:00:00 2001
From: Savely Krendelhoff <alicecandyom@proton.me>
Date: Sat, 6 Sep 2025 15:27:57 +0700
Subject: [PATCH] Add domain layer tests

---
 domain/entities_test.go | 219 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 219 insertions(+)
 create mode 100644 domain/entities_test.go

diff --git a/domain/entities_test.go b/domain/entities_test.go
new file mode 100644
index 0000000..73d7c98
--- /dev/null
+++ b/domain/entities_test.go
@@ -0,0 +1,219 @@
+package domain
+
+import (
+	"strings"
+	"testing"
+
+	"github.com/shopspring/decimal"
+)
+
+func TestNewCurrency(t *testing.T) {
+	tests := []struct {
+		name      string
+		code      string
+		currName  string
+		precision int
+		wantErr   bool
+	}{
+		{
+			name:      "valid currency",
+			code:      "USD",
+			currName:  "US Dollar",
+			precision: 2,
+			wantErr:   false,
+		},
+		{
+			name:      "empty code",
+			code:      "",
+			currName:  "Test",
+			precision: 2,
+			wantErr:   true,
+		},
+		{
+			name:      "whitespace code",
+			code:      "   ",
+			currName:  "Test",
+			precision: 2,
+			wantErr:   true,
+		},
+		{
+			name:      "negative precision",
+			code:      "BTC",
+			currName:  "Bitcoin",
+			precision: -1,
+			wantErr:   true,
+		},
+		{
+			name:      "lowercase code gets uppercase",
+			code:      "btc",
+			currName:  "Bitcoin",
+			precision: 8,
+			wantErr:   false,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			currency, err := NewCurrency(tt.code, tt.currName, tt.precision)
+			
+			if tt.wantErr {
+				if err == nil {
+					t.Errorf("NewCurrency() expected error but got none")
+				}
+				return
+			}
+
+			if err != nil {
+				t.Errorf("NewCurrency() unexpected error: %v", err)
+				return
+			}
+
+			expectedCode := strings.ToUpper(strings.TrimSpace(tt.code))
+			if currency.Code != expectedCode {
+				t.Errorf("NewCurrency() code = %s, want %s", currency.Code, expectedCode)
+			}
+
+			if currency.Precision != tt.precision {
+				t.Errorf("NewCurrency() precision = %d, want %d", currency.Precision, tt.precision)
+			}
+		})
+	}
+}
+
+func TestNewMoney(t *testing.T) {
+	currency, _ := NewCurrency("USD", "US Dollar", 2)
+	
+	tests := []struct {
+		name     string
+		amount   string
+		currency Currency
+		wantErr  bool
+	}{
+		{
+			name:     "valid amount",
+			amount:   "123.45",
+			currency: currency,
+			wantErr:  false,
+		},
+		{
+			name:     "zero amount",
+			amount:   "0",
+			currency: currency,
+			wantErr:  false,
+		},
+		{
+			name:     "empty amount",
+			amount:   "",
+			currency: currency,
+			wantErr:  true,
+		},
+		{
+			name:     "invalid amount format",
+			amount:   "abc",
+			currency: currency,
+			wantErr:  true,
+		},
+		{
+			name:     "negative amount",
+			amount:   "-123.45",
+			currency: currency,
+			wantErr:  true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			money, err := NewMoney(tt.amount, tt.currency)
+			
+			if tt.wantErr {
+				if err == nil {
+					t.Errorf("NewMoney() expected error but got none")
+				}
+				return
+			}
+
+			if err != nil {
+				t.Errorf("NewMoney() unexpected error: %v", err)
+				return
+			}
+
+			if money.Currency.Code != tt.currency.Code {
+				t.Errorf("NewMoney() currency = %s, want %s", money.Currency.Code, tt.currency.Code)
+			}
+		})
+	}
+}
+
+func TestNewRate(t *testing.T) {
+	usd, _ := NewCurrency("USD", "US Dollar", 2)
+	btc, _ := NewCurrency("BTC", "Bitcoin", 8)
+	
+	tests := []struct {
+		name    string
+		from    Currency
+		to      Currency
+		value   string
+		source  string
+		wantErr bool
+	}{
+		{
+			name:    "valid rate",
+			from:    usd,
+			to:      btc,
+			value:   "0.00001234",
+			source:  "test",
+			wantErr: false,
+		},
+		{
+			name:    "same currencies",
+			from:    usd,
+			to:      usd,
+			value:   "1.0",
+			source:  "test",
+			wantErr: true,
+		},
+		{
+			name:    "negative rate",
+			from:    usd,
+			to:      btc,
+			value:   "-0.00001234",
+			source:  "test",
+			wantErr: true,
+		},
+		{
+			name:    "zero rate",
+			from:    usd,
+			to:      btc,
+			value:   "0",
+			source:  "test",
+			wantErr: true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			value, _ := decimal.NewFromString(tt.value)
+			rate, err := NewRate(tt.from, tt.to, value, tt.source)
+			
+			if tt.wantErr {
+				if err == nil {
+					t.Errorf("NewRate() expected error but got none")
+				}
+				return
+			}
+
+			if err != nil {
+				t.Errorf("NewRate() unexpected error: %v", err)
+				return
+			}
+
+			if rate.From.Code != tt.from.Code {
+				t.Errorf("NewRate() from = %s, want %s", rate.From.Code, tt.from.Code)
+			}
+
+			if rate.To.Code != tt.to.Code {
+				t.Errorf("NewRate() to = %s, want %s", rate.To.Code, tt.to.Code)
+			}
+		})
+	}
+}
\ No newline at end of file