.gitignore

@@ -0,0 +1,213 @@
+## Ignore Visual Studio temporary files, build results, and
+## files generated by popular Visual Studio add-ons.
+
+# User-specific files
+*.rsuser
+*.suo
+*.user
+*.userosscache
+*.sln.docstates
+
+# Build results
+[Bb]in/
+[Oo]bj/
+[Ee]xt/
+[Ll]og/
+[Ll]ogs/
+
+# MSBuild Binary and Structured Log
+*.binlog
+
+# MSBuild response files
+!MSBuild.rsp
+!Directory.Build.rsp
+
+# Visual Studio 14+ cache/options directory
+.vs/
+
+# Visual Studio 15+ auto generated files
+Generated\ Files/
+
+# Local History for Visual Studio
+.localhistory/
+
+# Visual Studio History (VSHistory) files
+.vshistory/
+
+# Backup folder for Package Reference Convert tool in Visual Studio 2017
+MigrationBackup/
+
+# VS Code files for those working on multiple tools
+.vscode/*
+!.vscode/settings.json
+!.vscode/tasks.json
+!.vscode/launch.json
+!.vscode/extensions.json
+*.code-workspace
+
+# Local History for Visual Studio Code
+.history/
+
+# MSTest test Results
+[Tt]est[Rr]esult*/
+[Bb]uild[Ll]og.*
+
+# NUnit
+*.VisualState.xml
+TestResult.xml
+nunit-*.xml
+
+# Benchmark Results
+BenchmarkDotNet.Artifacts/
+
+# .NET Core
+project.lock.json
+project.fragment.lock.json
+artifacts/
+
+# ASP.NET Scaffolding
+ScaffoldingReadMe.txt
+
+# StyleCop
+StyleCopReport.xml
+
+# Files built by Visual Studio
+*_i.c
+*_p.c
+*_h.h
+*.ilk
+*.meta
+*.obj
+*.iobj
+*.pch
+*.pdb
+*.ipdb
+*.pgc
+*.pgd
+*.sbr
+*.tlb
+*.tli
+*.tlh
+*.tmp
+*.tmp_proj
+*_wpftmp.csproj
+*.log
+*.tlog
+*.vspscc
+*.vssscc
+.builds
+*.pidb
+*.svclog
+*.scc
+
+# Visual Studio profiler
+*.psess
+*.vsp
+*.vspx
+*.sap
+
+# Visual Studio Trace Files
+*.e2e
+
+# ReSharper is a .NET coding add-in
+_ReSharper*/
+*.[Rr]e[Ss]harper
+*.DotSettings.user
+
+# TeamCity is a build add-in
+_TeamCity*
+
+# DotCover is a Code Coverage Tool
+*.dotCover
+
+# AxoCover is a Code Coverage Tool
+.axoCover/*
+!.axoCover/settings.json
+
+# Coverlet is a free, cross platform Code Coverage Tool
+coverage*.json
+coverage*.xml
+coverage*.info
+
+# Visual Studio code coverage results
+*.coverage
+*.coveragexml
+
+# Publish Web Output
+*.[Pp]ublish.xml
+*.azurePubxml
+# Note: Comment the next line if you want to checkin your web deploy settings,
+# but database connection strings (with potential passwords) will be unencrypted
+*.pubxml
+*.publishproj
+
+# Microsoft Azure Web App publish settings. Comment the next line if you want to
+# checkin your Azure Web App publish settings, but sensitive information contained
+# in these scripts will be unencrypted
+PublishScripts/
+
+# NuGet Packages
+*.nupkg
+# NuGet Symbol Packages
+*.snupkg
+# The packages folder can be ignored because of Package Restore
+**/[Pp]ackages/*
+# except build/, which is used as an MSBuild target.
+!**/[Pp]ackages/build/
+# Uncomment if necessary however generally it will be regenerated when needed
+#!**/[Pp]ackages/repositories.config
+# NuGet v3's project.json files produces more ignorable files
+*.nuget.props
+*.nuget.targets
+
+# Windows Store app package directories and files
+AppPackages/
+BundleArtifacts/
+Package.StoreAssociation.xml
+_pkginfo.txt
+*.appx
+*.appxbundle
+*.appxupload
+
+# Visual Studio cache files
+# files ending in .cache can be ignored
+*.[Cc]ache
+# but keep track of directories ending in .cache
+!?*.[Cc]ache/
+
+# Others
+ClientBin/
+~$*
+*~
+*~.*
+*.dbmdl
+*.dbproj.schemaview
+*.jfm
+*.pfx
+*.publishsettings
+orleans.codegen.cs
+
+# RIA/Silverlight projects
+Generated_Code/
+
+# Backup & report files from converting an old project file
+# to a newer Visual Studio version. Backup files are not needed,
+# because we have git ;-)
+_UpgradeReport_Files/
+Backup*/
+UpgradeLog*.XML
+UpgradeLog*.htm
+ServiceFabricBackup/
+*.rptproj.bak
+
+# Microsoft Fakes
+FakesAssemblies/
+
+# CodeRush personal settings
+.cr/personal
+
+# JetBrains Rider
+*.sln.iml
+
+# Codex
+.codex

MutationCase.fs

@@ -1,4 +1,4 @@
-namespace Mutation
+namespace Mutannot
 
 open System
 

example-tests/Example.Tests/Calculator.fs

@@ -0,0 +1,10 @@
+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/Example.Tests/CalculatorTests.fs

@@ -0,0 +1,22 @@
+namespace Example.Tests
+
+open Example
+open Mutannot
+open Xunit
+
+type CalculatorTests() =
+    [<Fact>]
+    [<MutationCase("calc-add-one", "example-tests/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/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/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/Example.Tests.fsproj

@@ -0,0 +1,21 @@
+<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/Example.Tests/MutationCaseAttribute.fs

@@ -0,0 +1,13 @@
+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

verify-coverage-mutants.fsx

@@ -12,6 +12,11 @@ type MutationCase =
       TestName: string
       DeclaringType: string }
 
+type MutationOutcome =
+    | Killed
+    | Survived
+    | BuildFailed
+
 type Command =
     | List
     | Show of string
@@ -115,7 +120,7 @@ let mutationCases () =
         t.GetMethods(BindingFlags.Public ||| BindingFlags.NonPublic ||| BindingFlags.Static ||| BindingFlags.Instance)
         |> Array.collect (fun m ->
             m.GetCustomAttributesData()
-            |> Seq.filter (fun attr -> attr.AttributeType.FullName = "FsCheck.Test.MutationCaseAttribute")
+            |> Seq.filter (fun attr -> attr.AttributeType.FullName = "Mutannot.MutationCaseAttribute")
             |> Seq.map (fun attr ->
                 let args = attr.ConstructorArguments
                 if args.Count <> 5 then failwithf "Unexpected MutationCaseAttribute shape on %s.%s" t.FullName m.Name
@@ -203,15 +208,26 @@ let runMutation (mutation: MutationCase) =
     File.WriteAllText(targetFile, mutatedText)
 
     printfn "==> %s: %s" mutation.Id mutation.TestName
-    let exitCode = runProcess worktreePath "dotnet" [ "test"; testProjectPath; "--configuration"; options.Configuration; "--filter"; testFilter mutation; "--nologo" ]
-    File.WriteAllText(targetFile, originalText)
+    let buildExitCode =
+        runProcess worktreePath "dotnet" [ "build"; testProjectPath; "--configuration"; options.Configuration; "--nologo" ]
 
-    if exitCode = 0 then
+    let outcome =
+        if buildExitCode <> 0 then
+            printfn "BUILD FAILED %s" mutation.Id
+            BuildFailed
+        else
+            let testExitCode =
+                runProcess worktreePath "dotnet" [ "test"; testProjectPath; "--configuration"; options.Configuration; "--filter"; testFilter mutation; "--no-build"; "--nologo" ]
+
+            if testExitCode = 0 then
                 printfn "SURVIVED  %s" mutation.Id
-        false
+                Survived
             else
                 printfn "KILLED    %s" mutation.Id
-        true
+                Killed
+
+    File.WriteAllText(targetFile, originalText)
+    outcome
 
 let mutations = mutationCases ()
 
@@ -234,13 +250,14 @@ match options.Command with
 
     try
         createWorktree ()
-        let killed =
+        let outcomes =
             requested
             |> List.map runMutation
-        let survivors = killed |> List.filter not |> List.length
-        if survivors = 0 then
+        let survivors = outcomes |> List.filter ((=) Survived) |> List.length
+        let buildFailures = outcomes |> List.filter ((=) BuildFailed) |> List.length
+        if survivors = 0 && buildFailures = 0 then
             printfn "All requested mutants were killed."
         else
-            fail $"{survivors} mutant(s) survived."
+            fail $"{survivors} mutant(s) survived. {buildFailures} mutant(s) failed to build."
     finally
         cleanup ()