Make mutations patch-based

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)

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