test/langtools/jdk/javadoc/doclet/lib/JavadocTester.java
changeset 47216 71c04702a3d5
parent 44684 6ce4d52084e8
child 47328 d18df41954ba
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/langtools/jdk/javadoc/doclet/lib/JavadocTester.java	Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,840 @@
+/*
+ * Copyright (c) 2002, 2017, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+import java.io.BufferedWriter;
+import java.io.ByteArrayOutputStream;
+import java.io.File;
+import java.io.FileNotFoundException;
+import java.io.FileWriter;
+import java.io.FilenameFilter;
+import java.io.IOException;
+import java.io.PrintStream;
+import java.io.PrintWriter;
+import java.io.StringWriter;
+import java.lang.annotation.Annotation;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.ref.SoftReference;
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
+import java.nio.file.Files;
+import java.util.Arrays;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.EnumMap;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.function.Function;
+
+
+/**
+ * Test framework for running javadoc and performing tests on the resulting output.
+ *
+ * <p>
+ * Tests are typically written as subtypes of JavadocTester, with a main
+ * method that creates an instance of the test class and calls the runTests()
+ * method. The runTests() methods calls all the test methods declared in the class,
+ * and then calls a method to print a summary, and throw an exception if
+ * any of the test methods reported a failure.
+ *
+ * <p>
+ * Test methods are identified with a @Test annotation. They have no parameters.
+ * The name of the method is not important, but if you have more than one, it is
+ * recommended that the names be meaningful and suggestive of the test case
+ * contained therein.
+ *
+ * <p>
+ * Typically, a test method will invoke javadoc, and then perform various
+ * checks on the results. The standard checks are:
+ *
+ * <dl>
+ * <dt>checkExitCode
+ * <dd>Check the exit code returned from javadoc.
+ * <dt>checkOutput
+ * <dd>Perform a series of checks on the contents on a file or output stream
+ *     generated by javadoc.
+ *     The checks can be either that a series of strings are found or are not found.
+ * <dt>checkFiles
+ * <dd>Perform a series of checks on the files generated by javadoc.
+ *     The checks can be that a series of files are found or are not found.
+ * </dl>
+ *
+ * <pre><code>
+ *  public class MyTester extends JavadocTester {
+ *      public static void main(String... args) throws Exception {
+ *          MyTester tester = new MyTester();
+ *          tester.runTests();
+ *      }
+ *
+ *      // test methods...
+ *      @Test
+ *      void test() {
+ *          javadoc(<i>args</i>);
+ *          checkExit(Exit.OK);
+ *          checkOutput(<i>file</i>, true,
+ *              <i>strings-to-find</i>);
+ *          checkOutput(<i>file</i>, false,
+ *              <i>strings-to-not-find</i>);
+ *      }
+ *  }
+ * </code></pre>
+ *
+ * <p>
+ * If javadoc is run more than once in a test method, you can compare the
+ * results that are generated with the diff method. Since files written by
+ * javadoc typically contain a timestamp, you may want to use the -notimestamp
+ * option if you are going to compare the results from two runs of javadoc.
+ *
+ * <p>
+ * If you have many calls of checkOutput that are very similar, you can write
+ * your own check... method to reduce the amount of duplication. For example,
+ * if you want to check that many files contain the same string, you could
+ * write a method that takes a varargs list of files and calls checkOutput
+ * on each file in turn with the string to be checked.
+ *
+ * <p>
+ * You can also write you own custom check methods, which can use
+ * readFile to get the contents of a file generated by javadoc,
+ * and then use pass(...) or fail(...) to report whether the check
+ * succeeded or not.
+ *
+ * <p>
+ * You can have many separate test methods, each identified with a @Test
+ * annotation. However, you should <b>not</b> assume they will be called
+ * in the order declared in your source file.  If the order of a series
+ * of javadoc invocations is important, do that within a single method.
+ * If the invocations are independent, for better clarity, use separate
+ * test methods, each with their own set of checks on the results.
+ *
+ * @author Doug Kramer
+ * @author Jamie Ho
+ * @author Jonathan Gibbons (rewrite)
+ */
+public abstract class JavadocTester {
+
+    public static final String FS = System.getProperty("file.separator");
+    public static final String PS = System.getProperty("path.separator");
+    public static final String NL = System.getProperty("line.separator");
+
+    public enum Output {
+        /** The name of the output stream from javadoc. */
+        OUT,
+        /** The name for any output written to System.out. */
+        STDOUT,
+        /** The name for any output written to System.err. */
+        STDERR
+    }
+
+    /** The output directory used in the most recent call of javadoc. */
+    protected File outputDir;
+
+    /** The exit code of the most recent call of javadoc. */
+    private int exitCode;
+
+    /** The output generated by javadoc to the various writers and streams. */
+    private final Map<Output, String> outputMap = new EnumMap<>(Output.class);
+
+    /** A cache of file content, to avoid reading files unnecessarily. */
+    private final Map<File,SoftReference<String>> fileContentCache = new HashMap<>();
+
+    /** Stream used for logging messages. */
+    protected final PrintStream out = System.out;
+
+    /** The directory containing the source code for the test. */
+    public static final String testSrc = System.getProperty("test.src");
+
+    /**
+     * Get the path for a source file in the test source directory.
+     * @param path the path of a file or directory in the source directory
+     * @return the full path of the specified file
+     */
+    public static String testSrc(String path) {
+        return new File(testSrc, path).getPath();
+    }
+
+    /**
+     * Alternatives for checking the contents of a directory.
+     */
+    public enum DirectoryCheck {
+        /**
+         * Check that the directory is empty.
+         */
+        EMPTY((file, name) -> true),
+        /**
+         * Check that the directory does not contain any HTML files,
+         * such as may have been generated by a prior run of javadoc
+         * using this directory.
+         * For now, the check is only performed on the top level directory.
+         */
+        NO_HTML_FILES((file, name) -> name.endsWith(".html")),
+        /**
+         * No check is performed on the directory contents.
+         */
+        NONE(null) { @Override void check(File dir) { } };
+
+        /** The filter used to detect that files should <i>not</i> be present. */
+        FilenameFilter filter;
+
+        DirectoryCheck(FilenameFilter f) {
+            filter = f;
+        }
+
+        void check(File dir) {
+            if (dir.isDirectory()) {
+                String[] contents = dir.list(filter);
+                if (contents == null)
+                    throw new Error("cannot list directory: " + dir);
+                if (contents.length > 0) {
+                    System.err.println("Found extraneous files in dir:" + dir.getAbsolutePath());
+                    for (String x : contents) {
+                        System.err.println(x);
+                    }
+                    throw new Error("directory has unexpected content: " + dir);
+                }
+            }
+        }
+    }
+
+    private DirectoryCheck outputDirectoryCheck = DirectoryCheck.EMPTY;
+
+    /** The current subtest number. Incremented when checking(...) is called. */
+    private int numTestsRun = 0;
+
+    /** The number of subtests passed. Incremented when passed(...) is called. */
+    private int numTestsPassed = 0;
+
+    /** The current run of javadoc. Incremented when javadoc is called. */
+    private int javadocRunNum = 0;
+
+    /** Marker annotation for test methods to be invoked by runTests. */
+    @Retention(RetentionPolicy.RUNTIME)
+    @interface Test { }
+
+    /**
+     * Run all methods annotated with @Test, followed by printSummary.
+     * Typically called on a tester object in main()
+     * @throws Exception if any errors occurred
+     */
+    public void runTests() throws Exception {
+        runTests(m -> new Object[0]);
+    }
+
+    /**
+     * Run all methods annotated with @Test, followed by printSummary.
+     * Typically called on a tester object in main()
+     * @param f a function which will be used to provide arguments to each
+     *          invoked method
+     * @throws Exception if any errors occurred
+     */
+    public void runTests(Function<Method, Object[]> f) throws Exception {
+        for (Method m: getClass().getDeclaredMethods()) {
+            Annotation a = m.getAnnotation(Test.class);
+            if (a != null) {
+                try {
+                    out.println("Running test " + m.getName());
+                    m.invoke(this, f.apply(m));
+                } catch (InvocationTargetException e) {
+                    Throwable cause = e.getCause();
+                    throw (cause instanceof Exception) ? ((Exception) cause) : e;
+                }
+                out.println();
+            }
+        }
+        printSummary();
+    }
+
+    /**
+     * Run javadoc.
+     * The output directory used by this call and the final exit code
+     * will be saved for later use.
+     * To aid the reader, it is recommended that calls to this method
+     * put each option and the arguments it takes on a separate line.
+     *
+     * Example:
+     * <pre><code>
+     *  javadoc("-d", "out",
+     *          "-sourcepath", testSrc,
+     *          "-notimestamp",
+     *          "pkg1", "pkg2", "pkg3/C.java");
+     * </code></pre>
+     *
+     * @param args the arguments to pass to javadoc
+     */
+    public void javadoc(String... args) {
+        outputMap.clear();
+        fileContentCache.clear();
+
+        javadocRunNum++;
+        if (javadocRunNum == 1) {
+            out.println("Running javadoc...");
+        } else {
+            out.println("Running javadoc (run "
+                                    + javadocRunNum + ")...");
+        }
+        outputDir = new File(".");
+        for (int i = 0; i < args.length - 2; i++) {
+            if (args[i].equals("-d")) {
+                outputDir = new File(args[++i]);
+                break;
+            }
+        }
+        out.println("args: " + Arrays.toString(args));
+//        log.setOutDir(outputDir);
+
+        outputDirectoryCheck.check(outputDir);
+
+        // This is the sole stream used by javadoc
+        WriterOutput outOut = new WriterOutput();
+
+        // These are to catch output to System.out and System.err,
+        // in case these are used instead of the primary streams
+        StreamOutput sysOut = new StreamOutput(System.out, System::setOut);
+        StreamOutput sysErr = new StreamOutput(System.err, System::setErr);
+
+        try {
+            exitCode = jdk.javadoc.internal.tool.Main.execute(args, outOut.pw);
+        } finally {
+            outputMap.put(Output.STDOUT, sysOut.close());
+            outputMap.put(Output.STDERR, sysErr.close());
+            outputMap.put(Output.OUT, outOut.close());
+        }
+
+        outputMap.forEach((name, text) -> {
+            if (!text.isEmpty()) {
+                out.println("javadoc " + name + ":");
+                out.println(text);
+            }
+        });
+    }
+
+    /**
+     * Set the kind of check for the initial contents of the output directory
+     * before javadoc is run.
+     * The filter should return true for files that should <b>not</b> appear.
+     * @param c the kind of check to perform
+     */
+    public void setOutputDirectoryCheck(DirectoryCheck c) {
+        outputDirectoryCheck = c;
+    }
+
+    /**
+     * The exit codes returned by the javadoc tool.
+     * @see jdk.javadoc.internal.tool.Main.Result
+     */
+    public enum Exit {
+        OK(0),        // Javadoc completed with no errors.
+        ERROR(1),     // Completed but reported errors.
+        CMDERR(2),    // Bad command-line arguments
+        SYSERR(3),    // System error or resource exhaustion.
+        ABNORMAL(4);  // Javadoc terminated abnormally
+
+        Exit(int code) {
+            this.code = code;
+        }
+
+        final int code;
+
+        @Override
+        public String toString() {
+            return name() + '(' + code + ')';
+        }
+    }
+
+    /**
+     * Check the exit code of the most recent call of javadoc.
+     *
+     * @param expected the exit code that is required for the test
+     * to pass.
+     */
+    public void checkExit(Exit expected) {
+        checking("check exit code");
+        if (exitCode == expected.code) {
+            passed("return code " + exitCode);
+        } else {
+            failed("return code " + exitCode +"; expected " + expected);
+        }
+    }
+
+    /**
+     * Check for content in (or not in) the generated output.
+     * Within the search strings, the newline character \n
+     * will be translated to the platform newline character sequence.
+     * @param path a path within the most recent output directory
+     *  or the name of one of the output buffers, identifying
+     *  where to look for the search strings.
+     * @param expectedFound true if all of the search strings are expected
+     *  to be found, or false if the file is not expected to be found
+     * @param strings the strings to be searched for
+     */
+    public void checkFileAndOutput(String path, boolean expectedFound, String... strings) {
+        if (expectedFound) {
+            checkOutput(path, true, strings);
+        } else {
+            checkFiles(false, path);
+        }
+    }
+
+    /**
+     * Check for content in (or not in) the generated output.
+     * Within the search strings, the newline character \n
+     * will be translated to the platform newline character sequence.
+     * @param path a path within the most recent output directory
+     *  or the name of one of the output buffers, identifying
+     *  where to look for the search strings.
+     * @param expectedFound true if all of the search strings are expected
+     *  to be found, or false if all of the strings are expected to be
+     *  not found
+     * @param strings the strings to be searched for
+     */
+    public void checkOutput(String path, boolean expectedFound, String... strings) {
+        // Read contents of file
+        String fileString;
+        try {
+            fileString = readFile(outputDir, path);
+        } catch (Error e) {
+            checking("Read file");
+            failed("Error reading file: " + e);
+            return;
+        }
+        checkOutput(path, fileString, expectedFound, strings);
+    }
+
+    /**
+     * Check for content in (or not in) the one of the output streams written by
+     * javadoc. Within the search strings, the newline character \n
+     * will be translated to the platform newline character sequence.
+     * @param output the output stream to check
+     * @param expectedFound true if all of the search strings are expected
+     *  to be found, or false if all of the strings are expected to be
+     *  not found
+     * @param strings the strings to be searched for
+     */
+    public void checkOutput(Output output, boolean expectedFound, String... strings) {
+        checkOutput(output.toString(), outputMap.get(output), expectedFound, strings);
+    }
+
+    private void checkOutput(String path, String fileString, boolean expectedFound, String... strings) {
+        for (String stringToFind : strings) {
+//            log.logCheckOutput(path, expectedFound, stringToFind);
+            checking("checkOutput");
+            // Find string in file's contents
+            boolean isFound = findString(fileString, stringToFind);
+            if (isFound == expectedFound) {
+                passed(path + ": following text " + (isFound ? "found:" : "not found:") + "\n"
+                        + stringToFind + "\n");
+            } else {
+                failed(path + ": following text " + (isFound ? "found:" : "not found:") + "\n"
+                        + stringToFind + "\n");
+            }
+        }
+    }
+
+    /**
+     * Get the content of the one of the output streams written by
+     * javadoc.
+     */
+    public String getOutput(Output output) {
+        return outputMap.get(output);
+    }
+
+    /**
+     * Get the content of the one of the output streams written by
+     * javadoc.
+     */
+    public List<String> getOutputLines(Output output) {
+        String text = outputMap.get(output);
+        return (text == null) ? Collections.emptyList() : Arrays.asList(text.split(NL));
+    }
+
+    /**
+     * Check for files in (or not in) the generated output.
+     * @param expectedFound true if all of the files are expected
+     *  to be found, or false if all of the files are expected to be
+     *  not found
+     * @param paths the files to check, within the most recent output directory.
+     * */
+    public void checkFiles(boolean expectedFound, String... paths) {
+        checkFiles(expectedFound, Arrays.asList(paths));
+    }
+
+    /**
+     * Check for files in (or not in) the generated output.
+     * @param expectedFound true if all of the files are expected
+     *  to be found, or false if all of the files are expected to be
+     *  not found
+     * @param paths the files to check, within the most recent output directory.
+     * */
+    public void checkFiles(boolean expectedFound, Collection<String> paths) {
+        for (String path: paths) {
+//            log.logCheckFile(path, expectedFound);
+            checking("checkFile");
+            File file = new File(outputDir, path);
+            boolean isFound = file.exists();
+            if (isFound == expectedFound) {
+                passed(path + ": file " + (isFound ? "found:" : "not found:") + "\n");
+            } else {
+                failed(path + ": file " + (isFound ? "found:" : "not found:") + "\n");
+            }
+        }
+    }
+
+    /**
+     * Check that a series of strings are found in order in a file in
+     * the generated output.
+     * @param path the file to check
+     * @param strings  the strings whose order to check
+     */
+    public void checkOrder(String path, String... strings) {
+        String fileString = readOutputFile(path);
+        int prevIndex = -1;
+        for (String s : strings) {
+            s = s.replace("\n", NL); // normalize new lines
+            int currentIndex = fileString.indexOf(s);
+            checking(s + " at index " + currentIndex);
+            if (currentIndex == -1) {
+                failed(s + " not found.");
+                continue;
+            }
+            if (currentIndex > prevIndex) {
+                passed(s + " is in the correct order");
+            } else {
+                failed("file: " + path + ": " + s + " is in the wrong order.");
+            }
+            prevIndex = currentIndex;
+        }
+    }
+
+    /**
+     * Ensures that a series of strings appear only once, in the generated output,
+     * noting that, this test does not exhaustively check for all other possible
+     * duplicates once one is found.
+     * @param path the file to check
+     * @param strings ensure each are unique
+     */
+    public void checkUnique(String path, String... strings) {
+        String fileString = readOutputFile(path);
+        for (String s : strings) {
+            int currentIndex = fileString.indexOf(s);
+            checking(s + " at index " + currentIndex);
+            if (currentIndex == -1) {
+                failed(s + " not found.");
+                continue;
+            }
+            int nextindex = fileString.indexOf(s, currentIndex + s.length());
+            if (nextindex == -1) {
+                passed(s + " is unique");
+            } else {
+                failed(s + " is not unique, found at " + nextindex);
+            }
+        }
+    }
+
+    /**
+     * Compare a set of files in each of two directories.
+     *
+     * @param baseDir1 the directory containing the first set of files
+     * @param baseDir2 the directory containing the second set of files
+     * @param files the set of files to be compared
+     */
+    public void diff(String baseDir1, String baseDir2, String... files) {
+        File bd1 = new File(baseDir1);
+        File bd2 = new File(baseDir2);
+        for (String file : files) {
+            diff(bd1, bd2, file);
+        }
+    }
+
+    /**
+     * A utility to copy a directory from one place to another.
+     *
+     * @param targetDir the directory to copy.
+     * @param destDir the destination to copy the directory to.
+     */
+    // TODO: convert to using java.nio.Files.walkFileTree
+    public void copyDir(String targetDir, String destDir) {
+        try {
+            File targetDirObj = new File(targetDir);
+            File destDirParentObj = new File(destDir);
+            File destDirObj = new File(destDirParentObj, targetDirObj.getName());
+            if (! destDirParentObj.exists()) {
+                destDirParentObj.mkdir();
+            }
+            if (! destDirObj.exists()) {
+                destDirObj.mkdir();
+            }
+            String[] files = targetDirObj.list();
+            for (String file : files) {
+                File srcFile = new File(targetDirObj, file);
+                File destFile = new File(destDirObj, file);
+                if (srcFile.isFile()) {
+                    out.println("Copying " + srcFile + " to " + destFile);
+                    copyFile(destFile, srcFile);
+                } else if(srcFile.isDirectory()) {
+                    copyDir(srcFile.getAbsolutePath(), destDirObj.getAbsolutePath());
+                }
+            }
+        } catch (IOException exc) {
+            throw new Error("Could not copy " + targetDir + " to " + destDir);
+        }
+    }
+
+    /**
+     * Copy source file to destination file.
+     *
+     * @param destfile the destination file
+     * @param srcfile the source file
+     * @throws IOException
+     */
+    public void copyFile(File destfile, File srcfile) throws IOException {
+        Files.copy(srcfile.toPath(), destfile.toPath());
+    }
+
+    /**
+     * Read a file from the output directory.
+     *
+     * @param fileName  the name of the file to read
+     * @return          the file in string format
+     */
+    public String readOutputFile(String fileName) throws Error {
+        return readFile(outputDir, fileName);
+    }
+
+    protected String readFile(String fileName) throws Error {
+        return readFile(outputDir, fileName);
+    }
+
+    protected String readFile(String baseDir, String fileName) throws Error {
+        return readFile(new File(baseDir), fileName);
+    }
+
+    /**
+     * Read the file and return it as a string.
+     *
+     * @param baseDir   the directory in which to locate the file
+     * @param fileName  the name of the file to read
+     * @return          the file in string format
+     */
+    private String readFile(File baseDir, String fileName) throws Error {
+        try {
+            File file = new File(baseDir, fileName);
+            SoftReference<String> ref = fileContentCache.get(file);
+            String content = (ref == null) ? null : ref.get();
+            if (content != null)
+                return content;
+
+            content = new String(Files.readAllBytes(file.toPath()));
+            fileContentCache.put(file, new SoftReference<>(content));
+            return content;
+        } catch (FileNotFoundException e) {
+            throw new Error("File not found: " + fileName + ": " + e);
+        } catch (IOException e) {
+            throw new Error("Error reading file: " + fileName + ": " + e);
+        }
+    }
+
+    protected void checking(String message) {
+        numTestsRun++;
+        print("Starting subtest " + numTestsRun, message);
+    }
+
+    protected void passed(String message) {
+        numTestsPassed++;
+        print("Passed", message);
+    }
+
+    protected void failed(String message) {
+        print("FAILED", message);
+    }
+
+    private void print(String prefix, String message) {
+        if (message.isEmpty())
+            out.println(prefix);
+        else {
+            out.print(prefix);
+            out.print(": ");
+            out.println(message.replace("\n", NL));
+        }
+    }
+
+    /**
+     * Print a summary of the test results.
+     */
+    protected void printSummary() {
+        String javadocRuns = (javadocRunNum <= 1) ? ""
+                : ", in " + javadocRunNum + " runs of javadoc";
+
+        if (numTestsRun != 0 && numTestsPassed == numTestsRun) {
+            // Test passed
+            out.println();
+            out.println("All " + numTestsPassed + " subtests passed" + javadocRuns);
+        } else {
+            // Test failed
+            throw new Error((numTestsRun - numTestsPassed)
+                    + " of " + (numTestsRun)
+                    + " subtests failed"
+                    + javadocRuns);
+        }
+    }
+
+    /**
+     * Search for the string in the given file and return true
+     * if the string was found.
+     *
+     * @param fileString    the contents of the file to search through
+     * @param stringToFind  the string to search for
+     * @return              true if the string was found
+     */
+    private boolean findString(String fileString, String stringToFind) {
+        // javadoc (should) always use the platform newline sequence,
+        // but in the strings to find it is more convenient to use the Java
+        // newline character. So we translate \n to NL before we search.
+        stringToFind = stringToFind.replace("\n", NL);
+        return fileString.contains(stringToFind);
+    }
+
+    /**
+     * Compare the two given files.
+     *
+     * @param baseDir1 the directory in which to locate the first file
+     * @param baseDir2 the directory in which to locate the second file
+     * @param file the file to compare in the two base directories
+     * @param throwErrorIFNoMatch flag to indicate whether or not to throw
+     * an error if the files do not match.
+     * @return true if the files are the same and false otherwise.
+     */
+    private void diff(File baseDir1, File baseDir2, String file) {
+        String file1Contents = readFile(baseDir1, file);
+        String file2Contents = readFile(baseDir2, file);
+        checking("diff " + new File(baseDir1, file) + ", " + new File(baseDir2, file));
+        if (file1Contents.trim().compareTo(file2Contents.trim()) == 0) {
+            passed("files are equal");
+        } else {
+            failed("files differ");
+        }
+    }
+
+    /**
+     * Utility class to simplify the handling of temporarily setting a
+     * new stream for System.out or System.err.
+     */
+    private static class StreamOutput {
+        // functional interface to set a stream.
+        private interface Initializer {
+            void set(PrintStream s);
+        }
+
+        private final ByteArrayOutputStream baos = new ByteArrayOutputStream();
+        private final PrintStream ps = new PrintStream(baos);
+        private final PrintStream prev;
+        private final Initializer init;
+
+        StreamOutput(PrintStream s, Initializer init) {
+            prev = s;
+            init.set(ps);
+            this.init = init;
+        }
+
+        String close() {
+            init.set(prev);
+            ps.close();
+            return baos.toString();
+        }
+    }
+
+    /**
+     * Utility class to simplify the handling of creating an in-memory PrintWriter.
+     */
+    private static class WriterOutput {
+        private final StringWriter sw = new StringWriter();
+        final PrintWriter pw = new PrintWriter(sw);
+        String close() {
+            pw.close();
+            return sw.toString();
+        }
+    }
+
+
+//    private final Logger log = new Logger();
+
+    //--------- Logging --------------------------------------------------------
+    //
+    // This class writes out the details of calls to checkOutput and checkFile
+    // in a canonical way, so that the resulting file can be checked against
+    // similar files from other versions of JavadocTester using the same logging
+    // facilities.
+
+    static class Logger {
+        private static final int PREFIX = 40;
+        private static final int SUFFIX = 20;
+        private static final int MAX = PREFIX + SUFFIX;
+        List<String> tests = new ArrayList<>();
+        String outDir;
+        String rootDir = rootDir();
+
+        static String rootDir() {
+            File f = new File(".").getAbsoluteFile();
+            while (!new File(f, ".hg").exists())
+                f = f.getParentFile();
+            return f.getPath();
+        }
+
+        void setOutDir(File outDir) {
+            this.outDir = outDir.getPath();
+        }
+
+        void logCheckFile(String file, boolean positive) {
+            // Strip the outdir because that will typically not be the same
+            if (file.startsWith(outDir + "/"))
+                file = file.substring(outDir.length() + 1);
+            tests.add(file + " " + positive);
+        }
+
+        void logCheckOutput(String file, boolean positive, String text) {
+            // Compress the string to be displayed in the log file
+            String simpleText = text.replaceAll("\\s+", " ").replace(rootDir, "[ROOT]");
+            if (simpleText.length() > MAX)
+                simpleText = simpleText.substring(0, PREFIX)
+                        + "..." + simpleText.substring(simpleText.length() - SUFFIX);
+            // Strip the outdir because that will typically not be the same
+            if (file.startsWith(outDir + "/"))
+                file = file.substring(outDir.length() + 1);
+            // The use of text.hashCode ensure that all of "text" is taken into account
+            tests.add(file + " " + positive + " " + text.hashCode() + " " + simpleText);
+        }
+
+        void write() {
+            // sort the log entries because the subtests may not be executed in the same order
+            tests.sort((a, b) -> a.compareTo(b));
+            try (BufferedWriter bw = new BufferedWriter(new FileWriter("tester.log"))) {
+                for (String t: tests) {
+                    bw.write(t);
+                    bw.newLine();
+                }
+            } catch (IOException e) {
+                throw new Error("problem writing log: " + e);
+            }
+        }
+    }
+}