diff --git a/LehrerApp.Tests/LehrerApp.Tests.csproj b/LehrerApp.Tests/LehrerApp.Tests.csproj
new file mode 100644
index 0000000..5b38128
--- /dev/null
+++ b/LehrerApp.Tests/LehrerApp.Tests.csproj
@@ -0,0 +1,18 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <TargetFramework>net10.0</TargetFramework>
+    <IsPackable>false</IsPackable>
+    <IsTestProject>true</IsTestProject>
+  </PropertyGroup>
+  <ItemGroup>
+    <ProjectReference Include="..\LehrerApp.Core\LehrerApp.Core.csproj" />
+  </ItemGroup>
+  <ItemGroup>
+    <PackageReference Include="Microsoft.NET.Test.Sdk" />
+    <PackageReference Include="xunit" />
+    <PackageReference Include="xunit.runner.visualstudio">
+      <PrivateAssets>all</PrivateAssets>
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+    </PackageReference>
+  </ItemGroup>
+</Project>
diff --git a/LehrerApp.sln b/LehrerApp.sln
index 5dc2cd5..15087a2 100644
--- a/LehrerApp.sln
+++ b/LehrerApp.sln
@@ -1,4 +1,4 @@
-
+
 Microsoft Visual Studio Solution File, Format Version 12.00
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "LehrerApp.Core", "LehrerApp.Core\LehrerApp.Core.csproj", "{A1000001-0000-0000-0000-000000000001}"
 EndProject
@@ -12,23 +12,92 @@ Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "LehrerApp.Desktop", "Lehrer
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "LehrerApp.Data.Tests", "LehrerApp.Data.Tests\LehrerApp.Data.Tests.csproj", "{A1000006-0000-0000-0000-000000000006}"
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "LehrerApp.Tests", "LehrerApp.Tests\LehrerApp.Tests.csproj", "{4A5AC233-5976-44CD-B5F7-6562B096BA47}"
+EndProject
 Global
-  GlobalSection(SolutionConfigurationPlatforms) = preSolution
-    Debug|Any CPU = Debug|Any CPU
-    Release|Any CPU = Release|Any CPU
-  EndGlobalSection
-  GlobalSection(ProjectConfigurationPlatforms) = postSolution
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-    {A1000006-0000-0000-0000-000000000006}.Debug|Any CPU.Build.0 = Debug|Any CPU
-  EndGlobalSection
+	GlobalSection(SolutionConfigurationPlatforms) = preSolution
+		Debug|Any CPU = Debug|Any CPU
+		Debug|x64 = Debug|x64
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+		Release|x86 = Release|x86
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+		{A1000001-0000-0000-0000-000000000001}.Debug|x64.ActiveCfg = Debug|Any CPU
+		{A1000001-0000-0000-0000-000000000001}.Debug|x64.Build.0 = Debug|Any CPU
+		{A1000001-0000-0000-0000-000000000001}.Debug|x86.ActiveCfg = Debug|Any CPU
+		{A1000001-0000-0000-0000-000000000001}.Debug|x86.Build.0 = Debug|Any CPU
+		{A1000001-0000-0000-0000-000000000001}.Release|x64.ActiveCfg = Release|Any CPU
+		{A1000001-0000-0000-0000-000000000001}.Release|x64.Build.0 = Release|Any CPU
+		{A1000001-0000-0000-0000-000000000001}.Release|x86.ActiveCfg = Release|Any CPU
+		{A1000001-0000-0000-0000-000000000001}.Release|x86.Build.0 = Release|Any CPU
+		{A1000002-0000-0000-0000-000000000002}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{A1000002-0000-0000-0000-000000000002}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{A1000002-0000-0000-0000-000000000002}.Debug|x64.ActiveCfg = Debug|Any CPU
+		{A1000002-0000-0000-0000-000000000002}.Debug|x64.Build.0 = Debug|Any CPU
+		{A1000002-0000-0000-0000-000000000002}.Debug|x86.ActiveCfg = Debug|Any CPU
+		{A1000002-0000-0000-0000-000000000002}.Debug|x86.Build.0 = Debug|Any CPU
+		{A1000002-0000-0000-0000-000000000002}.Release|x64.ActiveCfg = Release|Any CPU
+		{A1000002-0000-0000-0000-000000000002}.Release|x64.Build.0 = Release|Any CPU
+		{A1000002-0000-0000-0000-000000000002}.Release|x86.ActiveCfg = Release|Any CPU
+		{A1000002-0000-0000-0000-000000000002}.Release|x86.Build.0 = Release|Any CPU
+		{A1000003-0000-0000-0000-000000000003}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{A1000003-0000-0000-0000-000000000003}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{A1000003-0000-0000-0000-000000000003}.Debug|x64.ActiveCfg = Debug|Any CPU
+		{A1000003-0000-0000-0000-000000000003}.Debug|x64.Build.0 = Debug|Any CPU
+		{A1000003-0000-0000-0000-000000000003}.Debug|x86.ActiveCfg = Debug|Any CPU
+		{A1000003-0000-0000-0000-000000000003}.Debug|x86.Build.0 = Debug|Any CPU
+		{A1000003-0000-0000-0000-000000000003}.Release|x64.ActiveCfg = Release|Any CPU
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+		{A1000004-0000-0000-0000-000000000004}.Release|x64.ActiveCfg = Release|Any CPU
+		{A1000004-0000-0000-0000-000000000004}.Release|x64.Build.0 = Release|Any CPU
+		{A1000004-0000-0000-0000-000000000004}.Release|x86.ActiveCfg = Release|Any CPU
+		{A1000004-0000-0000-0000-000000000004}.Release|x86.Build.0 = Release|Any CPU
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+		{A1000005-0000-0000-0000-000000000005}.Debug|x64.Build.0 = Debug|Any CPU
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+		{A1000005-0000-0000-0000-000000000005}.Debug|x86.Build.0 = Debug|Any CPU
+		{A1000005-0000-0000-0000-000000000005}.Release|x64.ActiveCfg = Release|Any CPU
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+		{A1000006-0000-0000-0000-000000000006}.Debug|x86.ActiveCfg = Debug|Any CPU
+		{A1000006-0000-0000-0000-000000000006}.Debug|x86.Build.0 = Debug|Any CPU
+		{A1000006-0000-0000-0000-000000000006}.Release|x64.ActiveCfg = Release|Any CPU
+		{A1000006-0000-0000-0000-000000000006}.Release|x64.Build.0 = Release|Any CPU
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+		{A1000006-0000-0000-0000-000000000006}.Release|x86.Build.0 = Release|Any CPU
+		{4A5AC233-5976-44CD-B5F7-6562B096BA47}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
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+		{4A5AC233-5976-44CD-B5F7-6562B096BA47}.Debug|x86.Build.0 = Debug|Any CPU
+		{4A5AC233-5976-44CD-B5F7-6562B096BA47}.Release|Any CPU.ActiveCfg = Release|Any CPU
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+		{4A5AC233-5976-44CD-B5F7-6562B096BA47}.Release|x64.Build.0 = Release|Any CPU
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 EndGlobal
diff --git a/TODO.md b/TODO.md
index 2c37a16..e1ac189 100644
--- a/TODO.md
+++ b/TODO.md
@@ -449,8 +449,9 @@ Fächer- und Kompetenzverwaltung existiert bereits in
 ## 13. Technische Basis
 
 ### 13.1 Tests
-- [ ] **13.1.1** Testprojekt `LehrerApp.Tests` anlegen (xunit-Pakete sind in
-      [Directory.Packages.props](Directory.Packages.props) bereits gepflegt, Projekt fehlt).
+- [x] **13.1.1** Testprojekt `LehrerApp.Tests` angelegt (referenziert `LehrerApp.Core`, analog zu
+      [LehrerApp.Data.Tests](LehrerApp.Data.Tests/LehrerApp.Data.Tests.csproj) für die Datenschicht).
+      Noch ohne Testfälle — folgt mit 13.1.2ff.
 - [ ] **13.1.2** Unit-Tests für `GradingService` (Notenschlüssel-Grenzfälle, gewichteter Schnitt).
 - [ ] **13.1.3** Unit-Tests für `SchoolYearService` (Jahreswechsel, Halbjahresgrenze).
 - [ ] **13.1.4** Repository-Tests gegen eine In-Memory-LiteDB.