Added ConfigurationReader

Author: Ja bist du narrisch

src/Migrator.Tests/Providers/SQLiteTransformationProviderTest.cs

@@ -13,6 +13,7 @@
 
 using Migrator.Framework;
 using Migrator.Providers.SQLite;
+using Migrator.Tests.Settings;
 using NUnit.Framework;
 
 namespace Migrator.Tests.Providers
@@ -21,8 +22,6 @@ namespace Migrator.Tests.Providers
 	[Category("SQLite")]
 	public class SQLiteTransformationProviderTest : TransformationProviderBase
 	{
-		#region Setup/Teardown
-
 		[SetUp]
 		public void SetUp()
 		{
@@ -36,8 +35,6 @@ public void SetUp()
 			AddDefaultTable();
 		}
 
-		#endregion
-
 		[Test]
 		public void AddForeignKey()
 		{

src/Migrator.Tests/Settings/ConfigurationReader.cs

@@ -0,0 +1,69 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using Microsoft.Extensions.Configuration;
+using Migrator.Tests.Settings.Interfaces;
+using Migrator.Tests.Settings.Models;
+
+namespace Migrator.Tests.Settings;
+
+/// <summary>
+/// Reads the configuration from appsettings.
+/// </summary>
+public class ConfigurationReader() : IConfigurationReader
+{
+    private const string AspnetCoreVariableString = "ASPNETCORE_ENVIRONMENT";
+
+    /// <summary>
+    /// Gets the database connection config by its ID.
+    /// </summary>
+    /// <param name="id">Use one of the IDs in <see cref="ConnectionIdentifiers"/></param>
+    /// <returns></returns>
+    public DatabaseConnectionConfig GetDatabaseConnectionConfigById(string id)
+    {
+        var configurationRoot = GetConfigurationRoot();
+        var aspNetCoreVariable = GetAspNetCoreEnvironmentVariable();
+
+        var databaseConnectionConfigs = configurationRoot.GetSection("DatabaseConnectionConfigs")
+            .Get<List<DatabaseConnectionConfig>>() ?? throw new KeyNotFoundException();
+
+        return databaseConnectionConfigs.Single(x => x.Id == id);
+    }
+
+    /// <summary>
+    /// Gets the configuration root. Currently it is not used for production therefore we do not use appsettings.json.
+    /// Your personal appsettings.Development.json will be used if your ASPNETCORE_ENVIRONMENT env variable is set to "Development".
+    /// </summary>
+    /// <returns></returns>
+    public IConfigurationRoot GetConfigurationRoot()
+    {
+        var aspNetCoreVariableName = GetAspNetCoreEnvironmentVariable();
+
+        return new ConfigurationBuilder()
+            .SetBasePath(AppDomain.CurrentDomain.BaseDirectory)
+            .AddJsonFile("appsettings.json", optional: false, reloadOnChange: false)
+            .AddJsonFile($"appsettings.{aspNetCoreVariableName}.json", optional: true, reloadOnChange: false)
+            .Build();
+    }
+
+    private static string GetAspNetCoreEnvironmentVariable()
+    {
+        var aspNetCoreVariable = Environment.GetEnvironmentVariable(AspnetCoreVariableString, EnvironmentVariableTarget.Process);
+
+        if (string.IsNullOrEmpty(aspNetCoreVariable))
+        {
+            aspNetCoreVariable = Environment.GetEnvironmentVariable(AspnetCoreVariableString, EnvironmentVariableTarget.User);
+        }
+        else if (string.IsNullOrEmpty(aspNetCoreVariable))
+        {
+            aspNetCoreVariable = Environment.GetEnvironmentVariable(AspnetCoreVariableString, EnvironmentVariableTarget.Machine);
+        }
+
+        if (string.IsNullOrWhiteSpace(aspNetCoreVariable))
+        {
+            throw new Exception($"The environment variable '{AspnetCoreVariableString}' is not set.");
+        }
+
+        return aspNetCoreVariable;
+    }
+}

src/Migrator.Tests/Settings/Interfaces/IConfigurationReader.cs

@@ -0,0 +1,8 @@
+using Migrator.Tests.Settings.Models;
+
+namespace Migrator.Tests.Settings.Interfaces;
+
+public interface IConfigurationReader
+{
+    DatabaseConnectionConfig GetDatabaseConnectionConfigById(string id);
+}

src/Migrator.Tests/Settings/Models/DatabaseConnectionConfig.cs

@@ -0,0 +1,11 @@
+namespace Migrator.Tests.Settings.Models;
+
+public class DatabaseConnectionConfig
+{
+    public string ConnectionString { get; set; }
+
+    /// <summary>
+    /// Gets or sets the connection identifier.
+    /// </summary>
+    public  string Id { get; set; }
+}