CNB Exchange rate provider - David Martin

jobs/Backend/ExchangeRateUpdater.Tests/CNBExchangeRateApiProviderTests.cs

@@ -0,0 +1,179 @@
+using System.Net;
+using System.Text.Json;
+using ExchangeRateUpdater.Models;
+using ExchangeRateUpdater.Providers;
+using Microsoft.Extensions.Configuration;
+using Microsoft.Extensions.Logging;
+using Moq;
+using Moq.Protected;
+
+namespace ExchangeRateUpdater.Tests.Providers;
+
+public class CNBExchangeRateApiProviderTests
+{
+    private readonly Mock<ILogger<CNBExchangeRateApiProvider>> _mockLogger;
+    private readonly Mock<HttpMessageHandler> _mockHttpMessageHandler;
+    private readonly HttpClient _httpClient;
+    private readonly IConfiguration _configuration;
+
+    public CNBExchangeRateApiProviderTests()
+    {
+        _mockLogger = new Mock<ILogger<CNBExchangeRateApiProvider>>();
+        _mockHttpMessageHandler = new Mock<HttpMessageHandler>();
+        _httpClient = new HttpClient(_mockHttpMessageHandler.Object);
+
+        var settings = new Dictionary<string, string?>
+        {
+            ["CNBExchangeRateAPIProvider:ApiBaseUrl"] = "https://api.cnb.cz",
+            ["CNBExchangeRateAPIProvider:DailyRatesEndpoint"] = "/cnbapi/exrates/daily",
+            ["CNBExchangeRateAPIProvider:TargetCurrencyCode"] = "CZK"
+        };
+
+        _configuration = new ConfigurationBuilder()
+            .AddInMemoryCollection(settings)
+            .Build();
+    }
+
+    #region Auxiliary Methods
+    private CNBExchangeRateApiProvider CreateProvider()
+        => new(_httpClient, _mockLogger.Object, _configuration);
+
+    private void SetupHttpResponse(HttpStatusCode statusCode, string content)
+    {
+        _mockHttpMessageHandler
+            .Protected()
+            .Setup<Task<HttpResponseMessage>>(
+                "SendAsync",
+                ItExpr.IsAny<HttpRequestMessage>(),
+                ItExpr.IsAny<CancellationToken>())
+            .ReturnsAsync(new HttpResponseMessage
+            {
+                StatusCode = statusCode,
+                Content = new StringContent(content)
+            });
+    }
+    #endregion
+
+
+    [Fact]
+    public async Task GetExchangeRatesAsync_WithValidResponse_ReturnsExchangeRates()
+    {
+        var currencies = new List<Currency>
+        {
+            new("USD"),
+            new("EUR")
+        };
+
+        var apiResponse = new
+        {
+            rates = new[]
+            {
+                new { currencyCode = "USD", amount = 1, rate = 20.367m },
+                new { currencyCode = "EUR", amount = 1, rate = 24.220m },
+                new { currencyCode = "JPY", amount = 100, rate = 13.044m }
+            }
+        };
+
+        SetupHttpResponse(HttpStatusCode.OK, JsonSerializer.Serialize(apiResponse));
+
+        var provider = CreateProvider();
+        var result = await provider.GetExchangeRatesAsync(currencies);
+
+        Assert.Equal(2, result.Count());
+        Assert.Contains(result, r => r.SourceCurrency.Code == "USD" && r.Value == 20.367m);
+        Assert.Contains(result, r => r.SourceCurrency.Code == "EUR" && r.Value == 24.220m);
+        Assert.DoesNotContain(result, r => r.SourceCurrency.Code == "JPY");
+    }
+
+    [Fact]
+    public async Task GetExchangeRatesAsync_NormalizesAmountCorrectly()
+    {
+        var currencies = new List<Currency> { new("JPY") };
+
+        var apiResponse = new
+        {
+            rates = new[]
+            {
+                new { currencyCode = "JPY", amount = 100, rate = 13.044m }
+            }
+        };
+
+        SetupHttpResponse(HttpStatusCode.OK, JsonSerializer.Serialize(apiResponse));
+
+        var provider = CreateProvider();
+        var result = await provider.GetExchangeRatesAsync(currencies);
+
+        var rate = Assert.Single(result);
+        Assert.Equal(0.13044m, rate.Value);
+    }
+
+    [Fact]
+    public async Task GetExchangeRatesAsync_WithNoCurrencies_ReturnsEmpty()
+    {
+        var provider = CreateProvider();
+        var result = await provider.GetExchangeRatesAsync([]);
+
+        Assert.Empty(result);
+    }
+
+    [Fact]
+    public async Task GetExchangeRatesAsync_WithHttpError_ReturnsEmptyAndLogsError()
+    {
+        SetupHttpResponse(HttpStatusCode.InternalServerError, "Server error");
+
+        var provider = CreateProvider();
+        var result = await provider.GetExchangeRatesAsync([new Currency("USD")]);
+
+        Assert.Empty(result);
+        _mockLogger.Verify(
+            x => x.Log(
+                LogLevel.Error,
+                It.IsAny<EventId>(),
+                It.Is<It.IsAnyType>((v, t) => v.ToString()!.Contains("Failed to fetch exchange rates from CNB API")),
+                It.IsAny<Exception>(),
+                It.Is<Func<It.IsAnyType, Exception?, string>>((v, t) => true)),
+            Times.Once);
+    }
+
+    [Fact]
+    public async Task GetExchangeRatesAsync_WithInvalidJson_ReturnsEmpty()
+    {
+        SetupHttpResponse(HttpStatusCode.OK, "invalid json {{{");
+
+        var provider = CreateProvider();
+        var result = await provider.GetExchangeRatesAsync([new Currency("USD")]);
+
+        Assert.Empty(result);
+        _mockLogger.Verify(
+            x => x.Log(
+                LogLevel.Error,
+                It.IsAny<EventId>(),
+                It.Is<It.IsAnyType>((v, t) => v.ToString()!.Contains("Failed to deserialize JSON response from CNB API")),
+                It.IsAny<JsonException>(),
+                It.Is<Func<It.IsAnyType, Exception?, string>>((v, t) => true)),
+            Times.Once);
+    }
+
+    [Fact]
+    public async Task GetExchangeRatesAsync_IgnoresTargetCurrency()
+    {
+        var currencies = new[] { new Currency("USD"), new Currency("CZK") };
+
+        var apiResponse = new
+        {
+            rates = new[]
+            {
+                new { currencyCode = "USD", amount = 1, rate = 20.367m },
+                new { currencyCode = "CZK", amount = 1, rate = 1.0m }
+            }
+        };
+
+        SetupHttpResponse(HttpStatusCode.OK, JsonSerializer.Serialize(apiResponse));
+
+        var provider = CreateProvider();
+        var result = await provider.GetExchangeRatesAsync(currencies);
+
+        var rate = Assert.Single(result);
+        Assert.Equal("USD", rate.SourceCurrency.Code);
+    }
+}

jobs/Backend/ExchangeRateUpdater.Tests/ExchangeRateUpdater.Tests.csproj

@@ -0,0 +1,27 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+	<PropertyGroup>
+		<TargetFramework>net10.0</TargetFramework>
+		<ImplicitUsings>enable</ImplicitUsings>
+		<Nullable>enable</Nullable>
+		<IsPackable>false</IsPackable>
+	</PropertyGroup>
+
+	<ItemGroup>
+		<PackageReference Include="coverlet.collector" Version="6.0.4" />
+		<PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.14.1" />
+		<PackageReference Include="xunit" Version="2.9.3" />
+		<PackageReference Include="xunit.runner.visualstudio" Version="3.1.4" />
+		<PackageReference Include="Moq" Version="4.20.70" />
+		<PackageReference Include="Microsoft.Extensions.Logging.Abstractions" Version="8.0.0" />
+	</ItemGroup>
+
+	<ItemGroup>
+		<Using Include="Xunit" />
+	</ItemGroup>
+
+	<ItemGroup>
+		<ProjectReference Include="..\Task\ExchangeRateUpdater.csproj" />
+	</ItemGroup>
+
+</Project>

jobs/Backend/Task/ExchangeRateUpdater.csproj

@@ -1,8 +1,21 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
-  <PropertyGroup>
-    <OutputType>Exe</OutputType>
-    <TargetFramework>net6.0</TargetFramework>
-  </PropertyGroup>
+	<PropertyGroup>
+		<OutputType>Exe</OutputType>
+		<TargetFramework>net10.0</TargetFramework>
+		<Nullable>enable</Nullable>
+	</PropertyGroup>
+
+	<ItemGroup>
+		<PackageReference Include="Microsoft.Extensions.Http.Polly" Version="8.0.0" />
+		<PackageReference Include="Microsoft.Extensions.Configuration.Json" Version="8.0.0" />
+		<PackageReference Include="Microsoft.Extensions.Logging.Console" Version="8.0.0" />
+	</ItemGroup>
+
+	<ItemGroup>
+		<None Update="appsettings.json">
+			<CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+		</None>
+	</ItemGroup>
 
 </Project>

jobs/Backend/Task/ExchangeRateUpdater.sln

@@ -1,10 +1,12 @@
 
 Microsoft Visual Studio Solution File, Format Version 12.00
-# Visual Studio 14
-VisualStudioVersion = 14.0.25123.0
+# Visual Studio Version 18
+VisualStudioVersion = 18.2.11415.280
 MinimumVisualStudioVersion = 10.0.40219.1
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "ExchangeRateUpdater", "ExchangeRateUpdater.csproj", "{7B2695D6-D24C-4460-A58E-A10F08550CE0}"
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "ExchangeRateUpdater.Tests", "..\ExchangeRateUpdater.Tests\ExchangeRateUpdater.Tests.csproj", "{30DD4A63-D42A-48E2-B0A3-1D07255842BB}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -15,8 +17,15 @@ Global
 		{7B2695D6-D24C-4460-A58E-A10F08550CE0}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{7B2695D6-D24C-4460-A58E-A10F08550CE0}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{7B2695D6-D24C-4460-A58E-A10F08550CE0}.Release|Any CPU.Build.0 = Release|Any CPU
+		{30DD4A63-D42A-48E2-B0A3-1D07255842BB}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{30DD4A63-D42A-48E2-B0A3-1D07255842BB}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{30DD4A63-D42A-48E2-B0A3-1D07255842BB}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{30DD4A63-D42A-48E2-B0A3-1D07255842BB}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
 	EndGlobalSection
+	GlobalSection(ExtensibilityGlobals) = postSolution
+		SolutionGuid = {C6C84BA4-B867-4ADB-939A-AB1C5DEACD1F}
+	EndGlobalSection
 EndGlobal

jobs/Backend/Task/Models/Currency.cs

@@ -0,0 +1,11 @@
+namespace ExchangeRateUpdater.Models;
+
+public class Currency(string code)
+{
+    /// <summary>
+    /// Three-letter ISO 4217 code of the currency.
+    /// </summary>
+    public string Code { get; } = code;
+
+    public override string ToString() => Code;
+}

jobs/Backend/Task/Models/ExchangeRate.cs

@@ -0,0 +1,12 @@
+namespace ExchangeRateUpdater.Models;
+
+public class ExchangeRate(Currency sourceCurrency, Currency targetCurrency, decimal value)
+{
+    public Currency SourceCurrency { get; } = sourceCurrency;
+
+    public Currency TargetCurrency { get; } = targetCurrency;
+
+    public decimal Value { get; } = value;
+
+    public override string ToString() => $"{SourceCurrency}/{TargetCurrency}={Value}";
+}