diff --git a/.gitignore b/.gitignore
index cbefbbf..809c7ad 100644
--- a/.gitignore
+++ b/.gitignore
@@ -3,3 +3,4 @@ bin/
 *.user
 .vs
 .idea
+Tests/Resources/Create.sql
diff --git a/Elwig/Helpers/AppDbContext.cs b/Elwig/Helpers/AppDbContext.cs
index ad3e144..30d9099 100644
--- a/Elwig/Helpers/AppDbContext.cs
+++ b/Elwig/Helpers/AppDbContext.cs
@@ -64,7 +64,8 @@ namespace Elwig.Helpers {
         public DateTime SavedLastWriteTime { get; private set; }
         public bool HasBackendChanged => SavedLastWriteTime != LastWriteTime;
 
-        public static string ConnectionString => $"Data Source=\"{App.Config.DatabaseFile}\"; Foreign Keys=True; Mode=ReadWrite; Cache=Default";
+        public static string? ConnectionStringOverride { get; set; } = null;
+        public static string ConnectionString => ConnectionStringOverride ?? $"Data Source=\"{App.Config.DatabaseFile}\"; Mode=ReadWrite; Foreign Keys=True; Cache=Default";
 
         private readonly Dictionary<int, Dictionary<int, Dictionary<string, AreaComBucket>>> _memberAreaCommitmentBuckets = [];
         private readonly Dictionary<int, Dictionary<int, Dictionary<string, int>>> _memberDeliveryBuckets = [];
diff --git a/Elwig/Helpers/AppDbUpdater.cs b/Elwig/Helpers/AppDbUpdater.cs
index 2c6d2a2..d7b6a8c 100644
--- a/Elwig/Helpers/AppDbUpdater.cs
+++ b/Elwig/Helpers/AppDbUpdater.cs
@@ -8,6 +8,7 @@ using System.Threading.Tasks;
 namespace Elwig.Helpers {
     public static class AppDbUpdater {
 
+        // Don't forget to update value in Tests/fetch-resources.bat!
         public static readonly int RequiredSchemaVersion = 12;
 
         private static int VersionOffset = 0;
diff --git a/Tests/DatabaseSetup.cs b/Tests/DatabaseSetup.cs
new file mode 100644
index 0000000..5de5b92
--- /dev/null
+++ b/Tests/DatabaseSetup.cs
@@ -0,0 +1,27 @@
+using Elwig.Helpers;
+using Microsoft.Data.Sqlite;
+using System.Reflection;
+
+namespace Tests {
+    [SetUpFixture]
+    public class DatabaseSetup {
+
+        private SqliteConnection? Connection;
+
+        [OneTimeSetUp]
+        public async Task SetupDatabase() {
+            AppDbContext.ConnectionStringOverride = $"Data Source=ElwigTestDB; Mode=Memory; Foreign Keys=True; Cache=Default";
+            Connection = await AppDbContext.ConnectAsync();
+            await AppDbContext.ExecuteEmbeddedScript(Connection, Assembly.GetExecutingAssembly(), "Tests.Resources.Create.sql");
+        }
+
+        [OneTimeTearDown]
+        public async Task TeardownDatabase() {
+            AppDbContext.ConnectionStringOverride = null;
+            if (Connection == null) return;
+            await Connection.DisposeAsync();
+            Connection = null;
+            // The in-memory database will be dropped if all connections to it are closed
+        }
+    }
+}
diff --git a/Tests/HelpersBillingTest.cs b/Tests/HelpersBillingTest.cs
new file mode 100644
index 0000000..9437504
--- /dev/null
+++ b/Tests/HelpersBillingTest.cs
@@ -0,0 +1,30 @@
+using Elwig.Helpers;
+using Microsoft.Data.Sqlite;
+using System.Reflection;
+
+namespace Tests {
+    [TestFixture]
+    public class HelpersBillingTest {
+
+        private SqliteConnection? Connection;
+
+        [OneTimeSetUp]
+        public async Task SetupDatabase() {
+            Connection = await AppDbContext.ConnectAsync();
+            await AppDbContext.ExecuteEmbeddedScript(Connection, Assembly.GetExecutingAssembly(), "Tests.Resources.BillingInsert.sql");
+        }
+
+        [OneTimeTearDown]
+        public async Task TeardownDatabase() {
+            if (Connection == null) return;
+            await AppDbContext.ExecuteEmbeddedScript(Connection, Assembly.GetExecutingAssembly(), "Tests.Resources.BillingDelete.sql");
+            await Connection.DisposeAsync();
+            Connection = null;
+        }
+
+        [Test]
+        public void Test() {
+            // TODO
+        }
+    }
+}
diff --git a/Tests/Resources/BillingDelete.sql b/Tests/Resources/BillingDelete.sql
new file mode 100644
index 0000000..694a2df
--- /dev/null
+++ b/Tests/Resources/BillingDelete.sql
@@ -0,0 +1 @@
+-- deletes for HelpersBillingTest
diff --git a/Tests/Resources/BillingInsert.sql b/Tests/Resources/BillingInsert.sql
new file mode 100644
index 0000000..604d7ac
--- /dev/null
+++ b/Tests/Resources/BillingInsert.sql
@@ -0,0 +1 @@
+-- inserts for HelpersBillingTest
diff --git a/Tests/Tests.csproj b/Tests/Tests.csproj
index 62b7d87..2c7ca58 100644
--- a/Tests/Tests.csproj
+++ b/Tests/Tests.csproj
@@ -9,6 +9,14 @@
     <IsTestProject>true</IsTestProject>
   </PropertyGroup>
 
+  <ItemGroup>
+    <EmbeddedResource Include="Resources\*.sql" />
+  </ItemGroup>
+
+  <Target Name="PreBuild" BeforeTargets="PreBuildEvent">
+    <Exec Command="call fetch-resources.bat" />
+  </Target>
+
   <ItemGroup>
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.3.2" />
     <PackageReference Include="NUnit" Version="3.13.3" />
diff --git a/Tests/fetch-resources.bat b/Tests/fetch-resources.bat
new file mode 100644
index 0000000..9df824e
--- /dev/null
+++ b/Tests/fetch-resources.bat
@@ -0,0 +1 @@
+curl -s "https://www.necronda.net/elwig/files/create.sql?v=12" -u "elwig:ganzGeheim123!" -o "Resources\Create.sql"