gradle-master/subprojects/internal-testing/src/main/groovy/org/gradle/test/fixtures/file/AbstractTestDirectoryProvider.java
/*
 * Copyright 2015 the original author or authors.
 *
 * Licensed 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.gradle.test.fixtures.file;

import groovy.lang.Closure;
import org.gradle.api.GradleException;
import org.gradle.test.fixtures.ConcurrentTestUtil;
import org.junit.rules.TestRule;
import org.junit.runner.Description;
import org.junit.runners.model.Statement;

import java.io.IOException;
import java.util.Random;
import java.util.regex.Pattern;


/**
 * A JUnit rule which provides a unique temporary folder for the test.
 *
 * Note: to avoid 260 char path length limitation on Windows, we should keep the test dir path as short as possible,
 * ideally < 90 chars (from repo root to test dir root, e.g. "core/build/tmp/teŝt files/{TestClass}/{testMethod}/qqlj8"),
 * or < 40 chars for "{TestClass}/{testMethod}/qqlj8"
 */
public abstract class AbstractTestDirectoryProvider implements TestRule, TestDirectoryProvider {
    protected final TestFile root;
    private final String className;

    private static final Random RANDOM = new Random();
    private static final int ALL_DIGITS_AND_LETTERS_RADIX = 36;
    private static final int MAX_RANDOM_PART_VALUE = Integer.parseInt("zzzzz", ALL_DIGITS_AND_LETTERS_RADIX);
    private static final Pattern WINDOWS_RESERVED_NAMES = Pattern.compile("(con)|(prn)|(aux)|(nul)|(com\\d)|(lpt\\d)", Pattern.CASE_INSENSITIVE);

    private String prefix;
    private TestFile dir;
    private boolean cleanup = true;
    private boolean suppressCleanupErrors = false;

    protected AbstractTestDirectoryProvider(TestFile root, Class<?> testClass) {
        this.root = root;
        this.className = shortenPath(testClass.getSimpleName(), 16);
    }

    @Override
    public void suppressCleanup() {
        cleanup = false;
    }

    @Override
    public void suppressCleanupErrors() {
        suppressCleanupErrors = true;
    }

    public boolean isCleanup() {
        return cleanup;
    }

    public void cleanup() {
        if (cleanup && dir != null && dir.exists()) {
            ConcurrentTestUtil.poll(new Closure(null, null) {
                @SuppressWarnings("UnusedDeclaration")
                void doCall() throws IOException {
                    dir.forceDeleteDir();
                }
            });
        }
    }

    @Override
    public Statement apply(final Statement base, Description description) {
        init(description.getMethodName());

        return new TestDirectoryCleaningStatement(base, description);
    }

    private class TestDirectoryCleaningStatement extends Statement {
        private final Statement base;
        private final Description description;

        TestDirectoryCleaningStatement(Statement base, Description description) {
            this.base = base;
            this.description = description;
        }

        @Override
        public void evaluate() throws Throwable {
            // implicitly don't clean up if this throws
            base.evaluate();

            try {
                cleanup();
            } catch (Exception e) {
                if (suppressCleanupErrors()) {
                    System.err.println(cleanupErrorMessage());
                    e.printStackTrace(System.err);
                } else {
                    throw new GradleException(cleanupErrorMessage(), e);
                }
            }
        }

        private boolean suppressCleanupErrors() {
            return suppressCleanupErrors
                || testClass().getAnnotation(LeaksFileHandles.class) != null
                || description.getAnnotation(LeaksFileHandles.class) != null;
        }

        private Class<?> testClass() {
            return description.getTestClass();
        }

        private String cleanupErrorMessage() {
            return "Couldn't delete test dir for `" + displayName() + "` (test is holding files open). "
                + "In order to find out which files are held open, you may find `org.gradle.integtests.fixtures.executer.GradleExecuter.withFileLeakDetection` useful.";
        }

        private String displayName() {
            return description.getDisplayName();
        }
    }

    protected void init(String methodName) {
        if (methodName == null) {
            // must be a @ClassRule; use the rule's class name instead
            methodName = getClass().getSimpleName();
        }
        if (prefix == null) {
            String safeMethodName = shortenPath(methodName.replaceAll("[^\\w]", "_"), 16);
            prefix = String.format("%s/%s", className, safeMethodName);
        }
    }

    /*
     Shorten a long name to at most {expectedMaxLength}, replace middle characters with ".".
     */
    private String shortenPath(String longName, int expectedMaxLength) {
        if (longName.length() <= expectedMaxLength) {
            return longName;
        } else {
            return longName.substring(0, expectedMaxLength - 5) + "." + longName.substring(longName.length() - 4);
        }
    }

    @Override
    public TestFile getTestDirectory() {
        if (dir == null) {
            dir = createUniqueTestDirectory();
        }
        return dir;
    }

    private TestFile createUniqueTestDirectory() {
        while (true) {
            // Use a random prefix to avoid reusing test directories
            String randomPrefix = Integer.toString(RANDOM.nextInt(MAX_RANDOM_PART_VALUE), ALL_DIGITS_AND_LETTERS_RADIX);
            if (WINDOWS_RESERVED_NAMES.matcher(randomPrefix).matches()) {
                continue;
            }
            TestFile dir = root.file(getPrefix(), randomPrefix);
            if (dir.mkdirs()) {
                return dir;
            }
        }
    }

    private String getPrefix() {
        if (prefix == null) {
            // This can happen if this is used in a constructor or a @Before method. It also happens when using
            // @RunWith(SomeRunner) when the runner does not support rules.
            prefix = className;
        }
        return prefix;
    }

    public TestFile file(Object... path) {
        return getTestDirectory().file(path);
    }

    public TestFile createFile(Object... path) {
        return file(path).createFile();
    }

    public TestFile createDir(Object... path) {
        return file(path).createDir();
    }
}
