commons-io_npe-5 (FuseFL)

여기서는 테스트가 독립된 2개의 테스트 실패가 아니라 테스트 하나 안의 정의한 메서드에서 fail이 뜨는거라 그냥 한번에 다 넘겨줌
실제 에러코드는 아래와 같음

    @SuppressWarnings("unchecked")
    public RegexFileFilter(final Pattern pattern) {
        this(pattern, (Function<Path, String> & Serializable) p -> p.getFileName().toString()); (114)
    }
    
        public RegexFileFilter(final Pattern pattern, final Function<Path, String> pathToString) {
        Objects.requireNonNull(pattern, "pattern");
        this.pattern = pattern;
        this.pathToString = pathToString; (128)
    }

    @Override
    public FileVisitResult accept(final Path path, final BasicFileAttributes attributes) {
        return toFileVisitResult(pattern.matcher(pathToString.apply(path)).matches()); (184)
    }

Provide a short code description of the following code:

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.commons.io.filefilter;

import java.io.File;
import java.io.Serializable;
import java.nio.file.FileVisitResult;
import java.nio.file.Path;
import java.nio.file.attribute.BasicFileAttributes;
import java.util.Objects;
import java.util.function.Function;
import java.util.regex.Pattern;

import org.apache.commons.io.IOCase;

/**
 * Filters files using supplied regular expression(s).
 * <p>
 * See java.util.regex.Pattern for regex matching rules.
 * </p>
 * <h2>Using Classic IO</h2>
 * <p>
 * e.g.
 *
 * <pre>
 * File dir = FileUtils.current();
 * FileFilter fileFilter = new RegexFileFilter("^.*[tT]est(-\\d+)?\\.java$");
 * File[] files = dir.listFiles(fileFilter);
 * for (String file : files) {
 *     System.out.println(file);
 * }
 * </pre>
 *
 * <h2>Using NIO</h2>
 *
 * <pre>
 * final Path dir = PathUtils.current();
 * final AccumulatorPathVisitor visitor = AccumulatorPathVisitor.withLongCounters(new RegexFileFilter("^.*[tT]est(-\\d+)?\\.java$"));
 * //
 * // Walk one dir
 * Files.<b>walkFileTree</b>(dir, Collections.emptySet(), 1, visitor);
 * System.out.println(visitor.getPathCounters());
 * System.out.println(visitor.getFileList());
 * //
 * visitor.getPathCounters().reset();
 * //
 * // Walk dir tree
 * Files.<b>walkFileTree</b>(dir, visitor);
 * System.out.println(visitor.getPathCounters());
 * System.out.println(visitor.getDirList());
 * System.out.println(visitor.getFileList());
 * </pre>
 * <h2>Deprecating Serialization</h2>
 * <p>
 * <em>Serialization is deprecated and will be removed in 3.0.</em>
 * </p>
 *
 * @since 1.4
 */
public class RegexFileFilter extends AbstractFileFilter implements Serializable {

    private static final long serialVersionUID = 4269646126155225062L;

    /**
     * Compiles the given pattern source.
     *
     * @param pattern the source pattern.
     * @param flags the compilation flags.
     * @return a new Pattern.
     */
    private static Pattern compile(final String pattern, final int flags) {
        Objects.requireNonNull(pattern, "pattern");
        return Pattern.compile(pattern, flags);
    }

    /**
     * Converts IOCase to Pattern compilation flags.
     *
     * @param ioCase case-sensitivity.
     * @return Pattern compilation flags.
     */
    private static int toFlags(final IOCase ioCase) {
        return IOCase.isCaseSensitive(ioCase) ? 0 : Pattern.CASE_INSENSITIVE;
    }

    /** The regular expression pattern that will be used to match file names. */
    private final Pattern pattern;

    /** How convert a path to a string. */
    private final Function<Path, String> pathToString;

    /**
     * Constructs a new regular expression filter for a compiled regular expression
     *
     * @param pattern regular expression to match.
     * @throws NullPointerException if the pattern is null.
     */
    @SuppressWarnings("unchecked")
    public RegexFileFilter(final Pattern pattern) {
        this(pattern, (Function<Path, String> & Serializable) p -> p.getFileName().toString());
    }

    /**
     * Constructs a new regular expression filter for a compiled regular expression
     *
     * @param pattern regular expression to match.
     * @param pathToString How convert a path to a string.
     * @throws NullPointerException if the pattern is null.
     * @since 2.10.0
     */
    public RegexFileFilter(final Pattern pattern, final Function<Path, String> pathToString) {
        Objects.requireNonNull(pattern, "pattern");
        this.pattern = pattern;
        this.pathToString = pathToString;
    }

    /**
     * Constructs a new regular expression filter.
     *
     * @param pattern regular string expression to match
     * @throws NullPointerException if the pattern is null
     */
    public RegexFileFilter(final String pattern) {
        this(pattern, 0);
    }

    /**
     * Constructs a new regular expression filter with the specified flags.
     *
     * @param pattern regular string expression to match
     * @param flags pattern flags - e.g. {@link Pattern#CASE_INSENSITIVE}
     * @throws IllegalArgumentException if the pattern is null
     */
    public RegexFileFilter(final String pattern, final int flags) {
        this(compile(pattern, flags));
    }

    /**
     * Constructs a new regular expression filter with the specified flags case sensitivity.
     *
     * @param pattern regular string expression to match
     * @param ioCase how to handle case sensitivity, null means case-sensitive
     * @throws IllegalArgumentException if the pattern is null
     */
    public RegexFileFilter(final String pattern, final IOCase ioCase) {
        this(compile(pattern, toFlags(ioCase)));
    }

    /**
     * Checks to see if the file name matches one of the regular expressions.
     *
     * @param dir the file directory (ignored)
     * @param name the file name
     * @return true if the file name matches one of the regular expressions
     */
    @Override
    public boolean accept(final File dir, final String name) {
        return pattern.matcher(name).matches();
    }

    /**
     * Checks to see if the file name matches one of the regular expressions.
     *
     * @param path the path
     * @param attributes the path attributes
     * @return true if the file name matches one of the regular expressions
     */
    @Override
    public FileVisitResult accept(final Path path, final BasicFileAttributes attributes) {
        return toFileVisitResult(pattern.matcher(pathToString.apply(path)).matches());
    }

    /**
     * Returns a debug string.
     *
     * @since 2.10.0
     */
    @Override
    public String toString() {
        return "RegexFileFilter [pattern=" + pattern + "]";
    }

}
```. 
The provided code is expected to pass these test cases: 

public void assertFiltering(final IOFileFilter filter, final Path path, final boolean expected) {
    // Note. This only tests the (Path, Path) version if the parent of
    // the Path passed in is not null
    final FileVisitResult expectedFileVisitResult = AbstractFileFilter.toDefaultFileVisitResult(expected);
    assertEquals(expectedFileVisitResult, filter.accept(path, null),
            "Filter(Path) " + filter.getClass().getName() + " not " + expectedFileVisitResult + " for " + path);
    assertEquals(expectedFileVisitResult != FileVisitResult.TERMINATE, filter.matches(path),
            "Filter(Path) " + filter.getClass().getName() + " not " + expectedFileVisitResult + " for " + path);

    if (path != null && path.getParent() != null) {
        assertEquals(expectedFileVisitResult, filter.accept(path, null),
                "Filter(Path, Path) " + filter.getClass().getName() + " not " + expectedFileVisitResult + " for "
                        + path);
    } else if (path == null) {
        assertEquals(expectedFileVisitResult, filter.accept(path, null),
                "Filter(Path, Path) " + filter.getClass().getName() + " not " + expectedFileVisitResult + " for null");
    }
    // Just don't blow up
    assertNotNull(filter.toString());
}

@SuppressWarnings("unchecked")
@Test
public void testRegexFileNameOnly() throws IOException {
    final Path path = Paths.get("folder", "Foo.java");
    final String patternStr = "Foo.*";
    assertFiltering(assertSerializable(new RegexFileFilter(patternStr)), path, true);
    assertFiltering(assertSerializable(new RegexFileFilter(Pattern.compile(patternStr), (Function<Path, String> & Serializable) Path::toString)), path,
            false);
    assertFiltering(new RegexFileFilter(Pattern.compile(patternStr), (Function<Path, String> & Serializable) null), path, false);
    assertFiltering(new RegexFileFilter(Pattern.compile(patternStr), (Function<Path, String> & Serializable) p -> null), path, false);
}

---

Faulty Code:

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.commons.io.filefilter;

import java.io.File;
import java.io.Serializable;
import java.nio.file.FileVisitResult;
import java.nio.file.Path;
import java.nio.file.attribute.BasicFileAttributes;
import java.util.Objects;
import java.util.function.Function;
import java.util.regex.Pattern;

import org.apache.commons.io.IOCase;

/**
 * Filters files using supplied regular expression(s).
 * <p>
 * See java.util.regex.Pattern for regex matching rules.
 * </p>
 * <h2>Using Classic IO</h2>
 * <p>
 * e.g.
 *
 * <pre>
 * File dir = FileUtils.current();
 * FileFilter fileFilter = new RegexFileFilter("^.*[tT]est(-\\d+)?\\.java$");
 * File[] files = dir.listFiles(fileFilter);
 * for (String file : files) {
 *     System.out.println(file);
 * }
 * </pre>
 *
 * <h2>Using NIO</h2>
 *
 * <pre>
 * final Path dir = PathUtils.current();
 * final AccumulatorPathVisitor visitor = AccumulatorPathVisitor.withLongCounters(new RegexFileFilter("^.*[tT]est(-\\d+)?\\.java$"));
 * //
 * // Walk one dir
 * Files.<b>walkFileTree</b>(dir, Collections.emptySet(), 1, visitor);
 * System.out.println(visitor.getPathCounters());
 * System.out.println(visitor.getFileList());
 * //
 * visitor.getPathCounters().reset();
 * //
 * // Walk dir tree
 * Files.<b>walkFileTree</b>(dir, visitor);
 * System.out.println(visitor.getPathCounters());
 * System.out.println(visitor.getDirList());
 * System.out.println(visitor.getFileList());
 * </pre>
 * <h2>Deprecating Serialization</h2>
 * <p>
 * <em>Serialization is deprecated and will be removed in 3.0.</em>
 * </p>
 *
 * @since 1.4
 */
public class RegexFileFilter extends AbstractFileFilter implements Serializable {

    private static final long serialVersionUID = 4269646126155225062L;

    /**
     * Compiles the given pattern source.
     *
     * @param pattern the source pattern.
     * @param flags the compilation flags.
     * @return a new Pattern.
     */
    private static Pattern compile(final String pattern, final int flags) {
        Objects.requireNonNull(pattern, "pattern");
        return Pattern.compile(pattern, flags);
    }

    /**
     * Converts IOCase to Pattern compilation flags.
     *
     * @param ioCase case-sensitivity.
     * @return Pattern compilation flags.
     */
    private static int toFlags(final IOCase ioCase) {
        return IOCase.isCaseSensitive(ioCase) ? 0 : Pattern.CASE_INSENSITIVE;
    }

    /** The regular expression pattern that will be used to match file names. */
    private final Pattern pattern;

    /** How convert a path to a string. */
    private final Function<Path, String> pathToString;

    /**
     * Constructs a new regular expression filter for a compiled regular expression
     *
     * @param pattern regular expression to match.
     * @throws NullPointerException if the pattern is null.
     */
    @SuppressWarnings("unchecked")
    public RegexFileFilter(final Pattern pattern) {
        this(pattern, (Function<Path, String> & Serializable) p -> p.getFileName().toString());
    }

    /**
     * Constructs a new regular expression filter for a compiled regular expression
     *
     * @param pattern regular expression to match.
     * @param pathToString How convert a path to a string.
     * @throws NullPointerException if the pattern is null.
     * @since 2.10.0
     */
    public RegexFileFilter(final Pattern pattern, final Function<Path, String> pathToString) {
        Objects.requireNonNull(pattern, "pattern");
        this.pattern = pattern;
        this.pathToString = pathToString;
    }

    /**
     * Constructs a new regular expression filter.
     *
     * @param pattern regular string expression to match
     * @throws NullPointerException if the pattern is null
     */
    public RegexFileFilter(final String pattern) {
        this(pattern, 0);
    }

    /**
     * Constructs a new regular expression filter with the specified flags.
     *
     * @param pattern regular string expression to match
     * @param flags pattern flags - e.g. {@link Pattern#CASE_INSENSITIVE}
     * @throws IllegalArgumentException if the pattern is null
     */
    public RegexFileFilter(final String pattern, final int flags) {
        this(compile(pattern, flags));
    }

    /**
     * Constructs a new regular expression filter with the specified flags case sensitivity.
     *
     * @param pattern regular string expression to match
     * @param ioCase how to handle case sensitivity, null means case-sensitive
     * @throws IllegalArgumentException if the pattern is null
     */
    public RegexFileFilter(final String pattern, final IOCase ioCase) {
        this(compile(pattern, toFlags(ioCase)));
    }

    /**
     * Checks to see if the file name matches one of the regular expressions.
     *
     * @param dir the file directory (ignored)
     * @param name the file name
     * @return true if the file name matches one of the regular expressions
     */
    @Override
    public boolean accept(final File dir, final String name) {
        return pattern.matcher(name).matches();
    }

    /**
     * Checks to see if the file name matches one of the regular expressions.
     *
     * @param path the path
     * @param attributes the path attributes
     * @return true if the file name matches one of the regular expressions
     */
    @Override
    public FileVisitResult accept(final Path path, final BasicFileAttributes attributes) {
        return toFileVisitResult(pattern.matcher(pathToString.apply(path)).matches());
    }

    /**
     * Returns a debug string.
     *
     * @since 2.10.0
     */
    @Override
    public String toString() {
        return "RegexFileFilter [pattern=" + pattern + "]";
    }

}

Task Description:
The provided code defines a Java class RegexFileFilter that is used to filter files based on regular expressions. Here is a detailed description:

Package and Imports
Package: org.apache.commons.io.filefilter
Imports: Various classes from java.io, java.nio.file, java.nio.file.attribute, java.util, java.util.function, and java.util.regex, as well as org.apache.commons.io.IOCase.
Class Overview
Class: RegexFileFilter
Inheritance: Extends AbstractFileFilter and implements Serializable.
Purpose: Filters files using supplied regular expression(s).
Class Members
serialVersionUID: A unique identifier for the serialization.
pattern: The regular expression pattern used to match file names.
pathToString: A function to convert a Path to a String.
Constructors
RegexFileFilter(Pattern pattern): Initializes the filter with a compiled regular expression pattern.
RegexFileFilter(Pattern pattern, Function<Path, String> pathToString): Initializes the filter with a compiled regular expression pattern and a function to convert paths to strings.
RegexFileFilter(String pattern): Initializes the filter with a regular expression pattern string.
RegexFileFilter(String pattern, int flags): Initializes the filter with a regular expression pattern string and compilation flags.
RegexFileFilter(String pattern, IOCase ioCase): Initializes the filter with a regular expression pattern string and case sensitivity settings.
Methods
compile(String pattern, int flags): Compiles the given pattern source with the specified flags.
toFlags(IOCase ioCase): Converts IOCase to Pattern compilation flags.
accept(File dir, String name): Checks if the file name matches the regular expression.
accept(Path path, BasicFileAttributes attributes): Checks if the file path matches the regular expression.
toString(): Returns a debug string representation of the filter.

Test Results:
The provided code is producing incorrect results. For examples:

• Running the function as follows filter.accept(path, null) generate a NullPointerException in line 184

               "Filter(Path) " + filter.getClass().getName() + " not " + expectedFileVisitResult + " for " + path);```

Spectrum-based Fault Localization (SBFL) Techniques Results:
We have used SBFL techniques to identify potentially faulty lines. Here are the results of top-[X] suspicious lines sorted in descending order of the score:
1. Line 184 return toFileVisitResult(pattern.matcher(pathToString.apply(path)).matches()); , SBFL
...
Analyze the provided code and utilize task description, test results, and SBFL techniques results to help in identifying potentially faulty lines. Provide the results following this JSON template:

{
  "faultLoc": [    {      "faultyLine": (indicating the line number of the suspicious code),      "code": (displaying the actual code),      "explanation": (step by step reasoning on why this location is considered potentially faulty)    },    ...  ]
}

---------------------------------------------응답------------------------------------------

{
  "faultLoc": [
    {
      "faultyLine": 184,
      "code": "return toFileVisitResult(pattern.matcher(pathToString.apply(path)).matches());",
      "explanation": "The NullPointerException occurs because `pathToString.apply(path)` might be returning null or `path` itself is null. If `path` is null, calling `pathToString.apply(path)` will throw a NullPointerException. The function should handle null paths more gracefully by adding a null check before applying the function."
    },
    {
      "faultyLine": 83,
      "code": "private final Function<Path, String> pathToString;",
      "explanation": "The `pathToString` function might not be properly initialized in some constructors, leading to potential null pointer issues when it is used. Ensure that `pathToString` is always non-null by initializing it in all constructors."
    },
    {
      "faultyLine": 115,
      "code": "this(pattern, (Function<Path, String> & Serializable) p -> p.getFileName().toString());",
      "explanation": "The default `pathToString` function assumes that the path has a valid file name. If `p.getFileName()` returns null, it will cause a NullPointerException. Adding a check to ensure `p.getFileName()` is non-null can prevent this issue."
    },
    {
      "faultyLine": 140,
      "code": "this(pattern, 0);",
      "explanation": "In this constructor, the pattern string is compiled with default flags. If the pattern string is null, it will cause a NullPointerException in the `compile` method. Adding a null check before compiling the pattern string would be beneficial."
    }
  ]
}

Line 184:

return toFileVisitResult(pattern.matcher(pathToString.apply(path)).matches());

Explanation:

This line calls pathToString.apply(path) which might be causing a NullPointerException if path is null or if pathToString.apply(path) returns null.
Fix: Add a null check for path and ensure pathToString function handles null values gracefully.

Line 83:

private final Function<Path, String> pathToString;

Explanation:

The pathToString function is a critical component and might not be initialized correctly in all constructors.
Fix: Ensure pathToString is always initialized properly, and it should handle null Path values without throwing exceptions.

Line 115:

this(pattern, (Function<Path, String> & Serializable) p -> p.getFileName().toString());

Explanation:

The default function p.getFileName().toString() assumes p.getFileName() is non-null, which might not always be the case.
Fix: Add null checks within the lambda to handle cases where p.getFileName() might return null.

Line 140:

this(pattern, 0);

Explanation:

If pattern is null when passed to this constructor, it will cause a NullPointerException during the compile method call.
Fix: Add a null check before compiling the pattern string to prevent potential NullPointerExceptions.
By addressing these identified issues, the RegexFileFilter class should handle null values more robustly and avoid NullPointerExceptions during execution

돌려보면 184빼곤 계속 달라짐