Move up Example.Tests a level

Example.Tests/Calculator.fs

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+namespace Example
+
+module Calculator =
+    let addOne value = value + 1
+
+    let absoluteDifference left right =
+        if left >= right then left - right else right - left
+
+    let isLeapYear year =
+        year % 4 = 0 && (year % 100 <> 0 || year % 400 = 0)

Example.Tests/CalculatorTests.fs

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+namespace Example.Tests
+
+open Example
+open Mutannot
+open Xunit
+
+type CalculatorTests() =
+    [<Fact>]
+    [<MutationCase("calc-add-one", "Example.Tests/Calculator.fs", 4, "value + 1", "value - 1")>]
+    member _.AddOne_increments() =
+        Assert.Equal(42, Calculator.addOne 41)
+
+    [<Fact>]
+    [<MutationCase("calc-abs-diff-branch", "Example.Tests/Calculator.fs", 7, "left - right", "right - left")>]
+    member _.AbsoluteDifference_preserves_order() =
+        Assert.Equal(7, Calculator.absoluteDifference 10 3)
+
+    [<Fact>]
+    [<MutationCase("calc-leap-year-century", "Example.Tests/Calculator.fs", 10, "year % 100 <> 0", "year % 100 = 0")>]
+    member _.LeapYear_handles_centuries() =
+        Assert.True(Calculator.isLeapYear 2000)
+        Assert.False(Calculator.isLeapYear 1900)

Example.Tests/Example.Tests.fsproj

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+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <TargetFramework>net10.0</TargetFramework>
+    <IsPackable>false</IsPackable>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <Compile Include="MutationCaseAttribute.fs" />
+    <Compile Include="Calculator.fs" />
+    <Compile Include="CalculatorTests.fs" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <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">
+      <PrivateAssets>all</PrivateAssets>
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+    </PackageReference>
+  </ItemGroup>
+</Project>

Example.Tests/MutationCaseAttribute.fs

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+namespace Mutannot
+
+open System
+
+[<AttributeUsage(AttributeTargets.Method, AllowMultiple = true)>]
+type MutationCaseAttribute(id: string, file: string, line: int, find: string, replace: string) =
+    inherit Attribute()
+
+    member _.Id = id
+    member _.File = file
+    member _.Line = line
+    member _.Find = find
+    member _.Replace = replace