fix(S1068): delete field writes as well (#917)

* Introduce failing test cases

* Remove field writes if they are not read

* Indicate noncompliance

sorald/src/main/java/sorald/processor/UnusedPrivateFieldProcessor.java

@@ -1,12 +1,29 @@
 package sorald.processor;
 
+import java.util.List;
 import sorald.annotations.ProcessorAnnotation;
+import spoon.reflect.code.CtFieldWrite;
+import spoon.reflect.code.CtStatement;
+import spoon.reflect.declaration.CtClass;
 import spoon.reflect.declaration.CtField;
+import spoon.reflect.visitor.filter.TypeFilter;
 
 @ProcessorAnnotation(key = "S1068", description = "Unused \"private\" fields should be removed")
 public class UnusedPrivateFieldProcessor extends SoraldAbstractProcessor<CtField<?>> {
     @Override
     protected void repairInternal(CtField<?> element) {
+        removeAllUnusedPrivateFieldWrites(element);
         element.delete();
     }
+
+    /** Removes all writes to the given field that are not read anywhere. */
+    private static void removeAllUnusedPrivateFieldWrites(CtField<?> field) {
+        CtClass<?> parentClass = field.getParent(CtClass.class);
+        List<CtFieldWrite<?>> unusedFieldWrites =
+                parentClass.filterChildren(new TypeFilter<>(CtFieldWrite.class)).list();
+        for (CtFieldWrite<?> unusedFieldWrite : unusedFieldWrites) {
+            CtStatement statement = unusedFieldWrite.getParent(CtStatement.class);
+            statement.delete();
+        }
+    }
 }

sorald/src/test/resources/processor_test_files/S1068_UnusedPrivateField/PrivateFieldWrittenButNotRead.java

@@ -0,0 +1,13 @@
+public class PrivateFieldWrittenButNotRead {
+    private int x; // Noncompliant
+
+    private String foo; // Noncompliant
+
+    public PrivateFieldWrittenButNotRead(int x, int y) {
+        this.x = x + y;
+    }
+
+    public void initialize(String bar) {
+        foo = bar;
+    }
+}

sorald/src/test/resources/processor_test_files/S1068_UnusedPrivateField/PrivateFieldWrittenButNotRead.java.expected

@@ -0,0 +1,6 @@
+public class PrivateFieldWrittenButNotRead {
+
+    public PrivateFieldWrittenButNotRead(int x, int y) { }
+
+    public void initialize(String bar) { }
+}