Myasuka commented on code in PR #20145:
URL: https://github.com/apache/flink/pull/20145#discussion_r913702461


##########
flink-test-utils-parent/flink-test-utils-junit/src/main/java/org/apache/flink/testutils/junit/extensions/parameterized/ParameterizedTestExtension.java:
##########
@@ -0,0 +1,250 @@
+/*
+ * 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.flink.testutils.junit.extensions.parameterized;
+
+import org.junit.jupiter.api.TestTemplate;
+import org.junit.jupiter.api.extension.BeforeEachCallback;
+import org.junit.jupiter.api.extension.Extension;
+import org.junit.jupiter.api.extension.ExtensionContext;
+import org.junit.jupiter.api.extension.ParameterContext;
+import org.junit.jupiter.api.extension.ParameterResolutionException;
+import org.junit.jupiter.api.extension.ParameterResolver;
+import org.junit.jupiter.api.extension.TestTemplateInvocationContext;
+import org.junit.jupiter.api.extension.TestTemplateInvocationContextProvider;
+import org.junit.platform.commons.support.AnnotationSupport;
+import org.junit.platform.commons.support.HierarchyTraversalMode;
+import org.junit.runners.Parameterized;
+
+import java.lang.reflect.Field;
+import java.lang.reflect.Method;
+import java.text.MessageFormat;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.List;
+import java.util.function.Function;
+import java.util.stream.Stream;
+
+/**
+ * This extension is used to implement parameterized tests for Junit 5 to 
replace {@link
+ * Parameterized}.
+ *
+ * <p>When use this extension, all tests must be annotated by {@link 
TestTemplate}.
+ */
+public class ParameterizedTestExtension implements 
TestTemplateInvocationContextProvider {
+
+    private static final ExtensionContext.Namespace NAMESPACE =
+            ExtensionContext.Namespace.create("parameterized");
+    private static final String PARAMETERS_STORE_KEY = "parameters";
+    private static final String PARAMETER_FIELD_STORE_KEY_PREFIX = 
"parameterField_";
+
+    @Override
+    public boolean supportsTestTemplate(ExtensionContext context) {
+        return true;
+    }
+
+    @Override
+    public Stream<TestTemplateInvocationContext> 
provideTestTemplateInvocationContexts(
+            ExtensionContext context) {
+
+        // Search method annotated with @Parameters
+        final List<Method> parameterProviders =
+                AnnotationSupport.findAnnotatedMethods(
+                        context.getRequiredTestClass(),
+                        Parameters.class,
+                        HierarchyTraversalMode.TOP_DOWN);
+        if (parameterProviders.isEmpty()) {
+            throw new IllegalStateException("Cannot find any parameter 
provider");
+        }
+        if (parameterProviders.size() > 1) {
+            throw new IllegalStateException("Multiple parameter providers are 
found");
+        }
+
+        // Get potential test name
+        String testNameTemplate = 
parameterProviders.get(0).getAnnotation(Parameters.class).name();

Review Comment:
   I can see many places have the usage of `parameterProviders.get(0)`, we can 
use just one variable to share it in many places.



##########
flink-test-utils-parent/flink-test-utils-junit/src/main/java/org/apache/flink/testutils/junit/extensions/parameterized/ParameterizedTestExtension.java:
##########
@@ -0,0 +1,250 @@
+/*
+ * 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.flink.testutils.junit.extensions.parameterized;
+
+import org.junit.jupiter.api.TestTemplate;
+import org.junit.jupiter.api.extension.BeforeEachCallback;
+import org.junit.jupiter.api.extension.Extension;
+import org.junit.jupiter.api.extension.ExtensionContext;
+import org.junit.jupiter.api.extension.ParameterContext;
+import org.junit.jupiter.api.extension.ParameterResolutionException;
+import org.junit.jupiter.api.extension.ParameterResolver;
+import org.junit.jupiter.api.extension.TestTemplateInvocationContext;
+import org.junit.jupiter.api.extension.TestTemplateInvocationContextProvider;
+import org.junit.platform.commons.support.AnnotationSupport;
+import org.junit.platform.commons.support.HierarchyTraversalMode;
+import org.junit.runners.Parameterized;
+
+import java.lang.reflect.Field;
+import java.lang.reflect.Method;
+import java.text.MessageFormat;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.List;
+import java.util.function.Function;
+import java.util.stream.Stream;
+
+/**
+ * This extension is used to implement parameterized tests for Junit 5 to 
replace {@link
+ * Parameterized}.
+ *
+ * <p>When use this extension, all tests must be annotated by {@link 
TestTemplate}.
+ */
+public class ParameterizedTestExtension implements 
TestTemplateInvocationContextProvider {
+
+    private static final ExtensionContext.Namespace NAMESPACE =
+            ExtensionContext.Namespace.create("parameterized");
+    private static final String PARAMETERS_STORE_KEY = "parameters";
+    private static final String PARAMETER_FIELD_STORE_KEY_PREFIX = 
"parameterField_";
+
+    @Override
+    public boolean supportsTestTemplate(ExtensionContext context) {
+        return true;
+    }
+
+    @Override
+    public Stream<TestTemplateInvocationContext> 
provideTestTemplateInvocationContexts(
+            ExtensionContext context) {
+
+        // Search method annotated with @Parameters
+        final List<Method> parameterProviders =
+                AnnotationSupport.findAnnotatedMethods(
+                        context.getRequiredTestClass(),
+                        Parameters.class,
+                        HierarchyTraversalMode.TOP_DOWN);
+        if (parameterProviders.isEmpty()) {
+            throw new IllegalStateException("Cannot find any parameter 
provider");
+        }
+        if (parameterProviders.size() > 1) {
+            throw new IllegalStateException("Multiple parameter providers are 
found");
+        }
+
+        // Get potential test name
+        String testNameTemplate = 
parameterProviders.get(0).getAnnotation(Parameters.class).name();
+
+        // Get parameter values
+        final Object parameterValues;
+        try {
+            parameterValues = parameterProviders.get(0).invoke(null);
+            context.getStore(NAMESPACE).put(PARAMETERS_STORE_KEY, 
parameterValues);
+        } catch (Exception e) {
+            throw new IllegalStateException("Failed to invoke parameter 
provider", e);
+        }
+        assert parameterValues != null;
+
+        // Parameter values could be Object[][]
+        if (parameterValues instanceof Object[][]) {
+            Object[][] typedParameterValues = (Object[][]) parameterValues;
+            return createContextForParameters(
+                    Arrays.stream(typedParameterValues), testNameTemplate, 
context);
+        }
+
+        // or a Collection
+        if (parameterValues instanceof Collection) {
+            final Collection<?> typedParameterValues = (Collection<?>) 
parameterValues;
+            final Stream<Object[]> parameterValueStream =
+                    typedParameterValues.stream()
+                            .map(
+                                    (Function<Object, Object[]>)
+                                            parameterValue -> {
+                                                if (parameterValue instanceof 
Object[]) {
+                                                    return (Object[]) 
parameterValue;
+                                                } else {
+                                                    return new Object[] 
{parameterValue};
+                                                }
+                                            });
+            return createContextForParameters(parameterValueStream, 
testNameTemplate, context);
+        }
+
+        throw new IllegalStateException(
+                String.format(
+                        "Return type of @Parameters annotated method \"%s\" 
should be either Object[][] or Collection",
+                        parameterProviders.get(0)));
+    }
+
+    private static class FieldInjectingInvocationContext implements 
TestTemplateInvocationContext {
+
+        private final String testNameTemplate;
+        private final Object[] parameterValues;
+
+        public FieldInjectingInvocationContext(String testNameTemplate, 
Object[] parameterValues) {
+            this.testNameTemplate = testNameTemplate;
+            this.parameterValues = parameterValues;
+        }
+
+        @Override
+        public String getDisplayName(int invocationIndex) {
+            if (testNameTemplate.equals("{index}")) {

Review Comment:
   I think we should avoid to use such magic string.



##########
flink-test-utils-parent/flink-test-utils-junit/src/main/java/org/apache/flink/testutils/junit/utils/TempDirUtils.java:
##########
@@ -0,0 +1,96 @@
+/*
+ * 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.flink.testutils.junit.utils;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.attribute.FileAttribute;
+
+/** The utils contains some methods same as {@link 
org.junit.rules.TemporaryFolder}. */
+public class TempDirUtils {

Review Comment:
   I found we lack a test to use this class, maybe 
`PackagedProgramUtilsPipelineTest.java` is a good choice.



##########
flink-test-utils-parent/flink-test-utils-junit/src/main/java/org/apache/flink/testutils/junit/extensions/parameterized/Parameters.java:
##########
@@ -0,0 +1,36 @@
+/*
+ * 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.flink.testutils.junit.extensions.parameterized;
+
+import org.junit.runners.Parameterized;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * The annotation is used to replace {@link Parameterized.Parameters} for 
Junit 5 parameterized

Review Comment:
   We should avoid importing junit4's class here.



##########
flink-test-utils-parent/flink-test-utils-junit/src/main/java/org/apache/flink/testutils/junit/extensions/parameterized/ParameterizedTestExtension.java:
##########
@@ -0,0 +1,250 @@
+/*
+ * 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.flink.testutils.junit.extensions.parameterized;
+
+import org.junit.jupiter.api.TestTemplate;
+import org.junit.jupiter.api.extension.BeforeEachCallback;
+import org.junit.jupiter.api.extension.Extension;
+import org.junit.jupiter.api.extension.ExtensionContext;
+import org.junit.jupiter.api.extension.ParameterContext;
+import org.junit.jupiter.api.extension.ParameterResolutionException;
+import org.junit.jupiter.api.extension.ParameterResolver;
+import org.junit.jupiter.api.extension.TestTemplateInvocationContext;
+import org.junit.jupiter.api.extension.TestTemplateInvocationContextProvider;
+import org.junit.platform.commons.support.AnnotationSupport;
+import org.junit.platform.commons.support.HierarchyTraversalMode;
+import org.junit.runners.Parameterized;
+
+import java.lang.reflect.Field;
+import java.lang.reflect.Method;
+import java.text.MessageFormat;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.List;
+import java.util.function.Function;
+import java.util.stream.Stream;
+
+/**
+ * This extension is used to implement parameterized tests for Junit 5 to 
replace {@link
+ * Parameterized}.

Review Comment:
   We should avoid to import junit4's class here.



##########
flink-test-utils-parent/flink-test-utils-junit/src/main/java/org/apache/flink/testutils/junit/utils/TempDirUtils.java:
##########
@@ -0,0 +1,96 @@
+/*
+ * 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.flink.testutils.junit.utils;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.attribute.FileAttribute;
+
+/** The utils contains some methods same as {@link 
org.junit.rules.TemporaryFolder}. */
+public class TempDirUtils {
+    private static final String TMP_PREFIX = "junit";
+
+    public static File newFolder(Path path) throws IOException {
+        Path tempPath;
+        if (path != null) {
+            tempPath = Files.createTempDirectory(path, TMP_PREFIX, new 
FileAttribute[0]);
+        } else {
+            tempPath = Files.createTempDirectory(TMP_PREFIX, new 
FileAttribute[0]);

Review Comment:
   I think we can use `Files.createTempDirectory(TMP_PREFIX)` to replace this.



##########
flink-test-utils-parent/flink-test-utils-junit/src/main/java/org/apache/flink/testutils/junit/utils/TempDirUtils.java:
##########
@@ -0,0 +1,96 @@
+/*
+ * 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.flink.testutils.junit.utils;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.attribute.FileAttribute;
+
+/** The utils contains some methods same as {@link 
org.junit.rules.TemporaryFolder}. */
+public class TempDirUtils {
+    private static final String TMP_PREFIX = "junit";
+
+    public static File newFolder(Path path) throws IOException {
+        Path tempPath;
+        if (path != null) {
+            tempPath = Files.createTempDirectory(path, TMP_PREFIX, new 
FileAttribute[0]);
+        } else {
+            tempPath = Files.createTempDirectory(TMP_PREFIX, new 
FileAttribute[0]);
+        }
+        return tempPath.toFile();
+    }
+
+    public static File newFile(Path path) throws IOException {
+        return File.createTempFile(TMP_PREFIX, null, path.toFile());
+    }
+
+    public static File newFolder(Path base, String... paths) throws 
IOException {
+        if (paths.length == 0) {
+            throw new IllegalArgumentException("must pass at least one path");
+        }
+
+        /*
+         * Before checking if the paths are absolute paths, check if create() 
was ever called,
+         * and if it wasn't, throw IllegalStateException.
+         */
+        File root = base.toFile();
+        for (String path : paths) {
+            if (new File(path).isAbsolute()) {
+                throw new IOException("folder path \'" + path + "\' is not a 
relative path");

Review Comment:
   ```suggestion
                   throw new IOException(String.format("folder path '%s' is not 
a relative path", path));
   ```



##########
flink-test-utils-parent/flink-test-utils-junit/src/main/java/org/apache/flink/testutils/junit/utils/TempDirUtils.java:
##########
@@ -0,0 +1,96 @@
+/*
+ * 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.flink.testutils.junit.utils;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.attribute.FileAttribute;
+
+/** The utils contains some methods same as {@link 
org.junit.rules.TemporaryFolder}. */

Review Comment:
   We should avoid referring junit4's class here.
   We can change it to `The utils contains some methods same as 
org.junit.rules.TemporaryFolder.`.



##########
flink-test-utils-parent/flink-test-utils-junit/src/main/java/org/apache/flink/testutils/junit/utils/TempDirUtils.java:
##########
@@ -0,0 +1,96 @@
+/*
+ * 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.flink.testutils.junit.utils;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.attribute.FileAttribute;
+
+/** The utils contains some methods same as {@link 
org.junit.rules.TemporaryFolder}. */
+public class TempDirUtils {
+    private static final String TMP_PREFIX = "junit";
+
+    public static File newFolder(Path path) throws IOException {
+        Path tempPath;
+        if (path != null) {
+            tempPath = Files.createTempDirectory(path, TMP_PREFIX, new 
FileAttribute[0]);
+        } else {
+            tempPath = Files.createTempDirectory(TMP_PREFIX, new 
FileAttribute[0]);
+        }
+        return tempPath.toFile();
+    }
+
+    public static File newFile(Path path) throws IOException {
+        return File.createTempFile(TMP_PREFIX, null, path.toFile());
+    }
+
+    public static File newFolder(Path base, String... paths) throws 
IOException {
+        if (paths.length == 0) {
+            throw new IllegalArgumentException("must pass at least one path");
+        }
+
+        /*
+         * Before checking if the paths are absolute paths, check if create() 
was ever called,
+         * and if it wasn't, throw IllegalStateException.
+         */
+        File root = base.toFile();
+        for (String path : paths) {
+            if (new File(path).isAbsolute()) {
+                throw new IOException("folder path \'" + path + "\' is not a 
relative path");
+            }
+        }
+
+        File relativePath = null;
+        File file = root;
+        boolean lastMkdirsCallSuccessful = true;
+        for (String path : paths) {
+            relativePath = new File(relativePath, path);
+            file = new File(root, relativePath.getPath());
+
+            lastMkdirsCallSuccessful = file.mkdirs();
+            if (!lastMkdirsCallSuccessful && !file.isDirectory()) {
+                if (file.exists()) {
+                    throw new IOException(
+                            "a file with the path \'" + relativePath.getPath() 
+ "\' exists");
+                } else {
+                    throw new IOException(
+                            "could not create a folder with the path \'"
+                                    + relativePath.getPath()
+                                    + "\'");
+                }
+            }
+        }
+        if (!lastMkdirsCallSuccessful) {
+            throw new IOException(
+                    "a folder with the path \'" + relativePath.getPath() + "\' 
already exists");
+        }
+        return file;
+    }
+
+    public static File newFile(Path folder, String fileName) throws 
IOException {
+        File file = new File(folder.toFile(), fileName);
+        if (!file.createNewFile()) {
+            throw new IOException(
+                    "a file with the name \'" + fileName + "\' already exists 
in the test folder");

Review Comment:
   Please update all similar places.



##########
flink-test-utils-parent/flink-test-utils-junit/src/main/java/org/apache/flink/testutils/junit/utils/TempDirUtils.java:
##########
@@ -0,0 +1,96 @@
+/*
+ * 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.flink.testutils.junit.utils;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.attribute.FileAttribute;
+
+/** The utils contains some methods same as {@link 
org.junit.rules.TemporaryFolder}. */
+public class TempDirUtils {
+    private static final String TMP_PREFIX = "junit";
+
+    public static File newFolder(Path path) throws IOException {
+        Path tempPath;
+        if (path != null) {
+            tempPath = Files.createTempDirectory(path, TMP_PREFIX, new 
FileAttribute[0]);
+        } else {
+            tempPath = Files.createTempDirectory(TMP_PREFIX, new 
FileAttribute[0]);
+        }
+        return tempPath.toFile();
+    }
+
+    public static File newFile(Path path) throws IOException {
+        return File.createTempFile(TMP_PREFIX, null, path.toFile());
+    }
+
+    public static File newFolder(Path base, String... paths) throws 
IOException {
+        if (paths.length == 0) {
+            throw new IllegalArgumentException("must pass at least one path");
+        }
+
+        /*
+         * Before checking if the paths are absolute paths, check if create() 
was ever called,
+         * and if it wasn't, throw IllegalStateException.
+         */
+        File root = base.toFile();
+        for (String path : paths) {
+            if (new File(path).isAbsolute()) {
+                throw new IOException("folder path \'" + path + "\' is not a 
relative path");
+            }
+        }
+
+        File relativePath = null;
+        File file = root;
+        boolean lastMkdirsCallSuccessful = true;
+        for (String path : paths) {
+            relativePath = new File(relativePath, path);
+            file = new File(root, relativePath.getPath());
+
+            lastMkdirsCallSuccessful = file.mkdirs();
+            if (!lastMkdirsCallSuccessful && !file.isDirectory()) {
+                if (file.exists()) {
+                    throw new IOException(
+                            "a file with the path \'" + relativePath.getPath() 
+ "\' exists");

Review Comment:
   ```suggestion
   String.format("a file with the path '%s' exists", relativePath.getPath()));
   ```



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