Phing > tests > remove mutation tests (because Infection requires PHP 7.1+)

phing/properties.dist

@@ -78,7 +78,5 @@ tests.database = ${dir.data.temporary}/database.sqlite
 
 # Paths of frameworks used to run tests:
 # - PHPUnit (unit tests)
-# - Infection (mutation tests)
 #
 tests.phpunit.command = ./vendor/bin/phpunit --verbose --no-coverage
-tests.mutation.command = ./vendor/bin/infection --threads=5

phing/tests.xml

@@ -51,8 +51,7 @@
 
     <!-- Test target -->
     <target name="build:test"
-            depends="test:phpunit,
-                    test:infection"
+            depends="test:phpunit"
     />
 
     <!-- Symfony2 code sniffer -->
@@ -104,11 +103,6 @@
         <exec command="${tests.phpunit.command}" passthru="true"/>
     </target>
 
-    <!-- Run mutation testing -->
-    <target name="test:infection" depends="build:prepare">
-        <exec command="${tests.mutation.command}" passthru="true"/>
-    </target>
-
     <!-- Project build clean -->
     <target name="build:clean">
         <if>