Issue #13809: Kill mutation in SuppressionCommentFilter

[Kevin222004]

Issue #13809: Kill mutation in SuppressionCommentFilter

---

Filters

https://checkstyle.sourceforge.io/filters/suppressioncommentfilter.html#SuppressionCommentFilter

---

Mutation

checkstyle/config/pitest-suppressions/pitest-filters-suppressions.xml

Lines 282 to 289 in 00f1780

	<mutation unstable="false">
	<sourceFile>SuppressionCommentFilter.java</sourceFile>
	<mutatedClass>com.puppycrawl.tools.checkstyle.filters.SuppressionCommentFilter</mutatedClass>
	<mutatedMethod>accept</mutatedMethod>
	<mutator>org.pitest.mutationtest.engine.gregor.mutators.NonVoidMethodCallMutator</mutator>
	<description>removed call to com/puppycrawl/tools/checkstyle/filters/SuppressionCommentFilter::getFileContents</description>
	<lineContent>if (getFileContents() != currentContents) {</lineContent>
	</mutation>

---

Explaination

test added.
Modified test prooves that exception is happening:

✔ ~/java/github/romani/checkstyle [Kevin222004/SuppressionCommentFilter L|✚ 2…1⚑ 1] 
 $ git diff
diff --git a/src/main/java/com/puppycrawl/tools/checkstyle/filters/SuppressionCommentFilter.java b/src/main/java/com/puppycrawl/tools/checkstyle/filters/SuppressionCommentFilter.java
index 5a82d0c..0a99106 100644
--- a/src/main/java/com/puppycrawl/tools/checkstyle/filters/SuppressionCommentFilter.java
+++ b/src/main/java/com/puppycrawl/tools/checkstyle/filters/SuppressionCommentFilter.java
@@ -285,7 +285,7 @@ public class SuppressionCommentFilter
             // contents and tag suppressions
             final FileContents currentContents = event.getFileContents();
 
-            if (getFileContents() != currentContents) {
+            if (true) {
                 setFileContents(currentContents);
                 tagSuppressions();
             }
diff --git a/src/test/java/com/puppycrawl/tools/checkstyle/filters/SuppressionCommentFilterTest.java b/src/test/java/com/puppycrawl/tools/checkstyle/filters/SuppressionCommentFilterTest.java
index 19ae666..65fcdaa 100644
--- a/src/test/java/com/puppycrawl/tools/checkstyle/filters/SuppressionCommentFilterTest.java
+++ b/src/test/java/com/puppycrawl/tools/checkstyle/filters/SuppressionCommentFilterTest.java
@@ -21,24 +21,33 @@ package com.puppycrawl.tools.checkstyle.filters;
 
 import static com.google.common.truth.Truth.assertWithMessage;
 import static com.puppycrawl.tools.checkstyle.checks.naming.AbstractNameCheck.MSG_INVALID_PATTERN;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
 
 import java.io.File;
 import java.util.Arrays;
 import java.util.List;
+import java.util.Map;
+import java.util.regex.Pattern;
 
 import org.junit.jupiter.api.Test;
 
 import com.puppycrawl.tools.checkstyle.AbstractModuleTestSupport;
 import com.puppycrawl.tools.checkstyle.DefaultConfiguration;
+import com.puppycrawl.tools.checkstyle.JavaParser;
 import com.puppycrawl.tools.checkstyle.TreeWalker;
 import com.puppycrawl.tools.checkstyle.TreeWalkerAuditEvent;
 import com.puppycrawl.tools.checkstyle.api.CheckstyleException;
+import com.puppycrawl.tools.checkstyle.api.DetailAST;
 import com.puppycrawl.tools.checkstyle.api.FileContents;
 import com.puppycrawl.tools.checkstyle.api.FileText;
+import com.puppycrawl.tools.checkstyle.api.SeverityLevel;
+import com.puppycrawl.tools.checkstyle.api.TextBlock;
 import com.puppycrawl.tools.checkstyle.api.Violation;
 import com.puppycrawl.tools.checkstyle.checks.coding.IllegalCatchCheck;
 import com.puppycrawl.tools.checkstyle.checks.naming.AbstractNameCheck;
 import com.puppycrawl.tools.checkstyle.checks.naming.ConstantNameCheck;
+import com.puppycrawl.tools.checkstyle.checks.naming.MemberNameCheck;
 import com.puppycrawl.tools.checkstyle.internal.utils.TestUtil;
 import com.puppycrawl.tools.checkstyle.utils.CommonUtil;
 import nl.jqno.equalsverifier.EqualsVerifier;
@@ -649,4 +658,57 @@ public class SuppressionCommentFilterTest
         return TestUtil.getInternalState(filter, "tags");
     }
 
+    @Test
+    public void testCachingByFilecontentInstance() throws Exception {
+
+        File file = new File(getPath("InputSuppressionCommentFilterSuppressById6.java"));
+        DetailAST rootast = JavaParser.parseFile(file, JavaParser.Options.WITH_COMMENTS);
+        String[] lines = {"//CSOFF", "//CSON"};
+        final FileContents fileContents = new FileContents(
+                new FileText(file, Arrays.asList(lines)));
+        for (int lineNo = 0; lineNo < lines.length; lineNo++) {
+            final int colNo = lines[lineNo].indexOf("//");
+            if (colNo >= 0) {
+                fileContents.reportSingleLineComment(lineNo + 1, colNo);}
+        }
+
+
+        final FileContents mockedContents = mock(FileContents.class);
+        Map<Integer, TextBlock> returnValue =
+                fileContents.getSingleLineComments();
+        when(mockedContents.getSingleLineComments())
+                .thenReturn(returnValue)
+                .thenThrow(new IllegalStateException("Second call is not allowed"));
+
+
+        String[] args = {"line_length", "^[a-z][a-zA-Z0-9]*$"};
+        Violation violation = new Violation(27, 9, 58,
+                "com.puppycrawl.tools.checkstyle.checks.naming.messages",
+                "name.invalidPattern",
+                args,
+                SeverityLevel.ERROR,
+                "ignore",
+                MemberNameCheck.class,
+                null);
+
+        TreeWalkerAuditEvent event = new TreeWalkerAuditEvent(
+                mockedContents, file.getAbsolutePath(), violation, rootast);
+
+        SuppressionCommentFilter ss = new SuppressionCommentFilter();
+        ss.setOffCommentFormat(Pattern.compile("CSOFF"));
+        ss.setOnCommentFormat(Pattern.compile("CSON"));
+        ss.setCheckFormat("MemberNameCheck");
+        ss.finishLocalSetup();
+
+        assertWithMessage("").that(ss.accept(event)).isTrue();
+        try {
+            ss.accept(event);
+            assertWithMessage("second execution expecting exception").fail();
+        } catch (IllegalStateException expected) {
+           assertWithMessage("exception is epected")
+                   .that(expected.getMessage())
+                   .isEqualTo("Second call is not allowed");
+        }
+    }
+
 }

[romani]

direction is good.

items:

[romani]

@Kevin222004 , let us know if you need more help to handle this PR .

[romani]

ok to merge