Add tests

BudgetApp.Tests/Models/AccountModelTests.cs

@@ -0,0 +1,63 @@
+using BudgetApp.Data;
+using Xunit;
+
+namespace BudgetApp.Tests.Models;
+
+public class AccountModelTests
+{
+    [Theory]
+    [InlineData("GBP", "£")]
+    [InlineData("USD", "$")]
+    [InlineData("EUR", "€")]
+    [InlineData("JPY", "¥")]
+    [InlineData("INR", "₹")]
+    public void GetSymbol_KnownCurrency_ReturnsSymbol(string code, string expected)
+    {
+        var account = new Account { CurrencyCode = code };
+        Assert.Equal(expected, account.GetSymbol());
+    }
+
+    [Fact]
+    public void GetSymbol_UnknownCurrency_ReturnsCurrencyCode()
+    {
+        var account = new Account { CurrencyCode = "XYZ" };
+        Assert.Equal("XYZ", account.GetSymbol());
+    }
+
+    [Fact]
+    public void FormatAmount_FormatsWithSymbolAndTwoDecimals()
+    {
+        var account = new Account { CurrencyCode = "GBP" };
+        Assert.Equal("£1,234.56", account.FormatAmount(1234.56m));
+    }
+
+    [Fact]
+    public void FormatAmount_NegativeAmount_IncludesMinusSign()
+    {
+        var account = new Account { CurrencyCode = "USD" };
+        Assert.Equal("$-50.00", account.FormatAmount(-50m));
+    }
+
+    [Fact]
+    public void FormatAmount_Zero_FormatsCorrectly()
+    {
+        var account = new Account { CurrencyCode = "EUR" };
+        Assert.Equal("€0.00", account.FormatAmount(0m));
+    }
+
+    [Fact]
+    public void CurrencySymbols_ContainsExpectedCount()
+    {
+        Assert.Equal(20, Account.CurrencySymbols.Count);
+    }
+
+    [Fact]
+    public void DefaultValues_AreCorrect()
+    {
+        var account = new Account();
+        Assert.Equal(string.Empty, account.Name);
+        Assert.Equal(0m, account.CurrentBalance);
+        Assert.Equal("#1b6ec2", account.Color);
+        Assert.Equal("GBP", account.CurrencyCode);
+    }
+}