Set up Infection

.gitattributes

@@ -1,14 +1,15 @@
-/.gitattributes export-ignore
-/.gitignore     export-ignore
-/.github        export-ignore
-/.phive         export-ignore
-/.php-cs-fixer.dist.php   export-ignore
-/.psalm         export-ignore
-/build          export-ignore
-/build.xml      export-ignore
-/phpunit.xml    export-ignore
-/tests          export-ignore
-/tools          export-ignore
-/tools/*        binary
+/.gitattributes         export-ignore
+/.gitignore             export-ignore
+/.github                export-ignore
+/.phive                 export-ignore
+/.php-cs-fixer.dist.php export-ignore
+/.psalm                 export-ignore
+/build                  export-ignore
+/build.xml              export-ignore
+infection.json5.dist    export-ignore
+/phpunit.xml            export-ignore
+/tests                  export-ignore
+/tools                  export-ignore
+/tools/*                binary
 
 *.php diff=php

.phive/phars.xml

@@ -3,4 +3,5 @@
   <phar name="php-cs-fixer" version="^3.0" installed="3.52.1" location="./tools/php-cs-fixer" copy="true"/>
   <phar name="psalm" version="^5.0" installed="5.23.1" location="./tools/psalm" copy="true"/>
   <phar name="composer" version="^2.0.3" installed="2.7.2" location="./tools/composer" copy="true"/>
+  <phar name="infection" version="^0.28.1" installed="0.28.1" location="./tools/infection" copy="true"/>
 </phive>

infection.json5.dist

@@ -0,0 +1,13 @@
+{
+    "$schema": "https://raw.githubusercontent.com/infection/infection/0.28.1/resources/schema.json",
+    "source": {
+        "directories": [
+            "src"
+        ]
+    },
+    "mutators": {
+        "@default": true
+    },
+    "minMsi": 100,
+    "minCoveredMsi": 100
+}