Add a dev dependency on infection

.editorconfig

@@ -0,0 +1,19 @@
+# http://editorconfig.org
+root = true
+
+[*]
+indent_style = space
+indent_size = 4
+charset = utf-8
+trim_trailing_whitespace = true
+insert_final_newline = true
+end_of_line = LF
+
+[*.md]
+trim_trailing_whitespace = false
+
+[Makefile]
+indent_style = tab
+
+[*.yml]
+indent_size = 2

.gitignore

@@ -9,3 +9,4 @@ docs
 phpunit.xml
 psalm.xml
 vendor
+infection.log

Makefile

@@ -4,6 +4,7 @@ help:
  @echo " test to perform tests."
  @echo " coverage to perform tests with code coverage."
  @echo " phpstan to run phpstan"
+ @echo " infection to run infection"
 
 install:
  composer install
@@ -16,3 +17,8 @@ coverage:
 
 phpstan:
  php vendor/bin/phpstan analyse
+
+INFECTION_THREADS = $(shell sysctl -n hw.ncpu)
+
+infection:
+ php vendor/bin/infection --threads=$(INFECTION_THREADS)

composer.json

@@ -32,6 +32,7 @@
  },
  "require-dev": {
  "phpunit/phpunit": "^7.5",
- "phpstan/phpstan": "0.12.56"
+ "phpstan/phpstan": "0.12.56",
+ "infection/infection": "^0.20.2"
  }
 }

infection.json.dist

@@ -0,0 +1,13 @@
+{
+ "source": {
+ "directories": [
+ "src"
+ ]
+ },
+ "logs": {
+ "text": "infection.log"
+ },
+ "mutators": {
+ "@default": true
+ }
+}