SONARJAVA-6143 Repair quickFix for S1118 rule (#5477)

Author: asya-vorobeva

java-checks-test-sources/default/src/main/java/checks/UtilityClassWithPublicConstructorCheckSample.java

@@ -257,4 +257,17 @@ public static String concatenate(String s1, String s2) {
     }
   }
 
+  // fix@qf4 {{Add an empty private constructor as the first member of the class.}}
+  // edit@qf4 [[sl=+0;el=+0;sc=43;ec=43]] {{\n    private StringUtilsWithBadOffsets() {\n      /* This utility class should not be instantiated */\n    }\n}}
+  // fix@qf5 {{Add an empty private constructor as the last member of the class.}}
+  // edit@qf5 [[sl=+5;el=+5;sc=6;ec=6]] {{\n\n    private StringUtilsWithBadOffsets() {\n      /* This utility class should not be instantiated */\n    }}}
+  // fix@qf6 {{Add an empty private constructor before the first method in the class.}}
+  // edit@qf6 [[sl=+1;el=+1;sc=45;ec=45]] {{\n\n    private StringUtilsWithBadOffsets() {\n      /* This utility class should not be instantiated */\n    }}}
+  public class StringUtilsWithBadOffsets { // Noncompliant [[sc=16;ec=41;quickfixes=qf4,qf5,qf6]]
+public static String HELLO = "Hello world!";
+
+ public static String concatenate(String s1, String s2) {
+      return s1 + s2;
+    }
+  }
 }

java-checks/src/main/java/org/sonar/java/checks/UtilityClassWithPublicConstructorCheck.java

@@ -21,6 +21,8 @@
 import java.util.List;
 import java.util.Set;
 import java.util.stream.Collectors;
+
+import org.apache.commons.lang3.tuple.Pair;
 import org.sonar.check.Rule;
 import org.sonar.java.checks.helpers.AnnotationsHelper;
 import org.sonar.java.checks.helpers.ClassPatternsUtils;
@@ -51,6 +53,8 @@ public class UtilityClassWithPublicConstructorCheck extends IssuableSubscription
     "lombok.AllArgsConstructor",
     "lombok.RequiredArgsConstructor");
 
+  private static final int DEFAULT_PADDING = 2;
+
   private static final Set<String> LOMBOK_CONSTRUCTOR_GENERATOR_NAMES =
     LOMBOK_CONSTRUCTOR_GENERATORS.stream()
       .map(AnnotationsHelper::annotationTypeIdentifier)
@@ -136,12 +140,7 @@ private static boolean isAccessLevelNotPublic(ExpressionTree tree) {
   }
 
   private static List<JavaQuickFix> computeQuickFixes(ClassTree classTree) {
-    int firstMemberColumnOffset = classTree.members().get(0).firstToken().range().start().columnOffset();
-    int columnOffsetDiff = firstMemberColumnOffset - classTree.firstToken().range().start().columnOffset();
-
-    String leftPadding = " ".repeat(firstMemberColumnOffset);
-    String constructor = leftPadding + "private " + classTree.simpleName() + "() {\n" + leftPadding + " ".repeat(columnOffsetDiff)
-      + "/* This utility class should not be instantiated */\n" + leftPadding + "}";
+    String constructor = buildPrivateConstructor(classTree);
 
     List<JavaQuickFix> quickFixes = new ArrayList<>();
     quickFixes.add(JavaQuickFix.newQuickFix("Add an empty private constructor as the first member of the class.")
@@ -163,4 +162,22 @@ private static List<JavaQuickFix> computeQuickFixes(ClassTree classTree) {
     return quickFixes;
   }
 
+  private static String buildPrivateConstructor(ClassTree classTree) {
+    int classColumnOffset = classTree.firstToken().range().start().columnOffset();
+    int firstMemberColumnOffset = classTree.members().get(0).firstToken().range().start().columnOffset();
+    Pair<Integer, Integer> paddings = calculatePaddingAmounts(classColumnOffset, firstMemberColumnOffset);
+
+    String declarationPadding = " ".repeat(paddings.getRight());
+    String bodyPadding = " ".repeat(paddings.getLeft());
+
+    return declarationPadding + "private " + classTree.simpleName() + "() {\n"
+      + declarationPadding + bodyPadding + "/* This utility class should not be instantiated */\n"
+      + declarationPadding + "}";
+  }
+
+  private static Pair<Integer, Integer> calculatePaddingAmounts(int classColumnOffset, int firstMemberColumnOffset) {
+    int colDiff = firstMemberColumnOffset - classColumnOffset;
+    return Pair.of(Math.max(DEFAULT_PADDING, colDiff), colDiff > 0 ? firstMemberColumnOffset : (classColumnOffset + DEFAULT_PADDING));
+  }
+
 }