Add mutation testing (#7)

.github/workflows/ca.yml

@@ -32,7 +32,7 @@ jobs:
         id: composer-cache
         uses: actions/cache@v3
         with:
-          path: vendor
+          path: ~/.cache/composer
           key: composer-${{ matrix.php-version }}-${{ hashFiles('composer.*') }}
           restore-keys: |
             composer-${{ matrix.php-version }}-

.github/workflows/cs.yml

@@ -32,7 +32,7 @@ jobs:
         id: composer-cache
         uses: actions/cache@v3
         with:
-          path: vendor
+          path: ~/.cache/composer
           key: composer-${{ matrix.php-version }}-${{ hashFiles('composer.*') }}
           restore-keys: |
             composer-${{ matrix.php-version }}-

.github/workflows/mt.yml

@@ -0,0 +1,48 @@
+# yamllint disable rule:line-length
+# yamllint disable rule:braces
+
+name: Mutation Testing
+
+on:
+  pull_request:
+  push:
+    branches:
+      - main
+
+permissions: read-all
+
+jobs:
+  build:
+    name: Mutatation testing with PHP ${{ matrix.php-version }}
+    runs-on: ubuntu-latest
+
+    strategy:
+      matrix:
+        php-version:
+          - "8.2"
+
+    steps:
+      - uses: actions/checkout@v3
+
+      - name: Setup PHP
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: ${{ matrix.php-version }}
+          coverage: pcov
+
+      - name: Cache Composer packages
+        uses: actions/cache@v3
+        with:
+          path: ~/.cache/composer
+          key: composer-${{ matrix.php-version }}-${{ hashFiles('composer.*') }}
+          restore-keys: |
+            composer-${{ matrix.php-version }}-
+            composer-
+
+      - name: Install dependencies
+        run: |
+          composer install --prefer-dist --no-progress
+
+      - name: Run Infection
+        run: |
+          make mt SILENT=

Makefile

@@ -30,9 +30,9 @@ COMPOSER=$(PHP) $(shell which composer)
 
 # Infection
 INFECTION=vendor/bin/infection
-MIN_MSI=50
-MIN_COVERED_MSI=50
-INFECTION_ARGS=--min-msi=$(MIN_MSI) --min-covered-msi=$(MIN_COVERED_MSI) --threads=$(JOBS) --coverage=build/logs --show-mutations --no-interaction --only-covered --only-covering-test-cases
+MIN_MSI=84
+MIN_COVERED_MSI=84
+INFECTION_ARGS=--min-msi=$(MIN_MSI) --min-covered-msi=$(MIN_COVERED_MSI) --threads=$(JOBS) --coverage=build/logs --show-mutations --no-interaction
 
 all: test
 
@@ -56,8 +56,8 @@ phpunit-coverage: cs prerequisites
 	rm -fr build/logs/*
 	$(SILENT) $(PHP) $(PHPUNIT) $(PHPUNIT_ARGS)
 
-.PHONY: infection
-infection: phpunit-coverage prerequisites infection.json.dist
+.PHONY: mt
+mt: phpunit-coverage prerequisites infection.json.dist
 	$(SILENT) $(PHP) $(INFECTION) $(INFECTION_ARGS)
 
 .PHONY: sa

infection.json.dist

@@ -0,0 +1,11 @@
+{
+    "$schema": "vendor/infection/infection/resources/schema.json",
+    "source": {
+        "directories": [
+            "src"
+        ]
+    },
+    "mutators": {
+        "@default": true
+    }
+}