From 2dc2c288fb41e984c1e7f25d48615e32816c3681 Mon Sep 17 00:00:00 2001
From: Sven van Heugten <sven@memcmp.org>
Date: Tue, 12 May 2026 08:07:43 +0200
Subject: [PATCH] Make mutations patch-based

---
 Example.Tests/CalculatorTests.fs       | 29 +++++++++++++++-----------
 Example.Tests/MutationCaseAttribute.fs |  8 ++-----
 Mutannot/Program.fs                    |  4 ++--
 3 files changed, 21 insertions(+), 20 deletions(-)

diff --git a/Example.Tests/CalculatorTests.fs b/Example.Tests/CalculatorTests.fs
index 40f9b66..0a96e10 100644
--- a/Example.Tests/CalculatorTests.fs
+++ b/Example.Tests/CalculatorTests.fs
@@ -6,17 +6,22 @@ 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)
+    [<MutationCase("""
+    diff --git a/Example.Tests/Calculator.fs b/Example.Tests/Calculator.fs
+    index cfcce3b..39be7f3 100644
+    --- a/Example.Tests/Calculator.fs
+    +++ b/Example.Tests/Calculator.fs
+    @@ -1,7 +1,7 @@
+     namespace Example
 
-    [<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)
+     module Calculator =
+    -    let addOne value = value + 1
+    +    let addOne value = value - 1
 
-    [<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)
+         let absoluteDifference left right =
+             if left >= right then left - right else right - left
+
+        member _.AddOne_increments() =
+            Assert.Equal(42, Calculator.addOne 41)
+    """)>]
+    member _.AddOne_increments() = Assert.Equal(42, Calculator.addOne 41)
diff --git a/Example.Tests/MutationCaseAttribute.fs b/Example.Tests/MutationCaseAttribute.fs
index 12e6475..f1175e4 100644
--- a/Example.Tests/MutationCaseAttribute.fs
+++ b/Example.Tests/MutationCaseAttribute.fs
@@ -3,11 +3,7 @@ namespace Mutannot
 open System
 
 [<AttributeUsage(AttributeTargets.Method, AllowMultiple = true)>]
-type MutationCaseAttribute(id: string, file: string, line: int, find: string, replace: string) =
+type MutationCaseAttribute(patch: string) =
     inherit Attribute()
 
-    member _.Id = id
-    member _.File = file
-    member _.Line = line
-    member _.Find = find
-    member _.Replace = replace
+    member _.Patch = patch
diff --git a/Mutannot/Program.fs b/Mutannot/Program.fs
index 5c3a1ac..6cd78aa 100644
--- a/Mutannot/Program.fs
+++ b/Mutannot/Program.fs
@@ -4,7 +4,7 @@ open System.Reflection
 open System.Runtime.InteropServices
 open Fli
 
-type MutationCase = { TestName: string; Id: string }
+type MutationCase = { TestName: string; Patch: string }
 
 let ensureBuilt projectPath =
     cli {
@@ -60,7 +60,7 @@ let getMutationCases projectPath =
             | "Mutannot.MutationCaseAttribute" ->
                 Some
                     { TestName = $"{m.DeclaringType.FullName}.{m.Name}"
-                      Id = attr.ConstructorArguments[0].Value :?> string }
+                      Patch = attr.ConstructorArguments[0].Value :?> string }
             | _ -> None))
     |> Seq.toList