Utils.java revision 2757:d2f32a6fef00
1/*
2 * Copyright (c) 2013, 2017, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 */
23
24package jdk.test.lib;
25
26import java.io.File;
27import java.io.IOException;
28import java.net.InetAddress;
29import java.net.MalformedURLException;
30import java.net.ServerSocket;
31import java.net.URL;
32import java.net.URLClassLoader;
33import java.net.UnknownHostException;
34import java.nio.file.Files;
35import java.nio.file.Path;
36import java.nio.file.Paths;
37import java.util.ArrayList;
38import java.util.Arrays;
39import java.util.Collection;
40import java.util.Collections;
41import java.util.Iterator;
42import java.util.Map;
43import java.util.HashMap;
44import java.util.List;
45import java.util.Objects;
46import java.util.Random;
47import java.util.function.BooleanSupplier;
48import java.util.concurrent.TimeUnit;
49import java.util.function.Consumer;
50import java.util.function.Function;
51import java.util.regex.Matcher;
52import java.util.regex.Pattern;
53
54import static jdk.test.lib.Asserts.assertTrue;
55import jdk.test.lib.process.ProcessTools;
56import jdk.test.lib.process.OutputAnalyzer;
57
58/**
59 * Common library for various test helper functions.
60 */
61public final class Utils {
62
63    /**
64     * Returns the value of 'test.class.path' system property.
65     */
66    public static final String TEST_CLASS_PATH = System.getProperty("test.class.path", ".");
67
68    /**
69     * Returns the sequence used by operating system to separate lines.
70     */
71    public static final String NEW_LINE = System.getProperty("line.separator");
72
73    /**
74     * Returns the value of 'test.vm.opts' system property.
75     */
76    public static final String VM_OPTIONS = System.getProperty("test.vm.opts", "").trim();
77
78    /**
79     * Returns the value of 'test.java.opts' system property.
80     */
81    public static final String JAVA_OPTIONS = System.getProperty("test.java.opts", "").trim();
82
83    /**
84     * Returns the value of 'test.src' system property.
85     */
86    public static final String TEST_SRC = System.getProperty("test.src", "").trim();
87
88    /*
89     * Returns the value of 'test.jdk' system property
90     */
91    public static final String TEST_JDK = System.getProperty("test.jdk");
92
93    /*
94     * Returns the value of 'compile.jdk' system property
95     */
96    public static final String COMPILE_JDK= System.getProperty("compile.jdk", TEST_JDK);
97
98    /**
99     * Returns the value of 'test.classes' system property
100     */
101    public static final String TEST_CLASSES = System.getProperty("test.classes", ".");
102    /**
103     * Defines property name for seed value.
104     */
105    public static final String SEED_PROPERTY_NAME = "jdk.test.lib.random.seed";
106
107    /* (non-javadoc)
108     * Random generator with (or without) predefined seed. Depends on
109     * "jdk.test.lib.random.seed" property value.
110     */
111    private static volatile Random RANDOM_GENERATOR;
112
113    /**
114     * Contains the seed value used for {@link java.util.Random} creation.
115     */
116    public static final long SEED = Long.getLong(SEED_PROPERTY_NAME, new Random().nextLong());
117    /**
118    * Returns the value of 'test.timeout.factor' system property
119    * converted to {@code double}.
120    */
121    public static final double TIMEOUT_FACTOR;
122    static {
123        String toFactor = System.getProperty("test.timeout.factor", "1.0");
124        TIMEOUT_FACTOR = Double.parseDouble(toFactor);
125    }
126
127    /**
128    * Returns the value of JTREG default test timeout in milliseconds
129    * converted to {@code long}.
130    */
131    public static final long DEFAULT_TEST_TIMEOUT = TimeUnit.SECONDS.toMillis(120);
132
133    private Utils() {
134        // Private constructor to prevent class instantiation
135    }
136
137    /**
138     * Returns the list of VM options.
139     *
140     * @return List of VM options
141     */
142    public static List<String> getVmOptions() {
143        return Arrays.asList(safeSplitString(VM_OPTIONS));
144    }
145
146    /**
147     * Returns the list of VM options with -J prefix.
148     *
149     * @return The list of VM options with -J prefix
150     */
151    public static List<String> getForwardVmOptions() {
152        String[] opts = safeSplitString(VM_OPTIONS);
153        for (int i = 0; i < opts.length; i++) {
154            opts[i] = "-J" + opts[i];
155        }
156        return Arrays.asList(opts);
157    }
158
159    /**
160     * Returns the default JTReg arguments for a jvm running a test.
161     * This is the combination of JTReg arguments test.vm.opts and test.java.opts.
162     * @return An array of options, or an empty array if no options.
163     */
164    public static String[] getTestJavaOpts() {
165        List<String> opts = new ArrayList<String>();
166        Collections.addAll(opts, safeSplitString(VM_OPTIONS));
167        Collections.addAll(opts, safeSplitString(JAVA_OPTIONS));
168        return opts.toArray(new String[0]);
169    }
170
171    /**
172     * Combines given arguments with default JTReg arguments for a jvm running a test.
173     * This is the combination of JTReg arguments test.vm.opts and test.java.opts
174     * @return The combination of JTReg test java options and user args.
175     */
176    public static String[] addTestJavaOpts(String... userArgs) {
177        List<String> opts = new ArrayList<String>();
178        Collections.addAll(opts, getTestJavaOpts());
179        Collections.addAll(opts, userArgs);
180        return opts.toArray(new String[0]);
181    }
182
183    /**
184     * Removes any options specifying which GC to use, for example "-XX:+UseG1GC".
185     * Removes any options matching: -XX:(+/-)Use*GC
186     * Used when a test need to set its own GC version. Then any
187     * GC specified by the framework must first be removed.
188     * @return A copy of given opts with all GC options removed.
189     */
190    private static final Pattern useGcPattern = Pattern.compile(
191            "(?:\\-XX\\:[\\+\\-]Use.+GC)"
192            + "|(?:\\-Xconcgc)");
193    public static List<String> removeGcOpts(List<String> opts) {
194        List<String> optsWithoutGC = new ArrayList<String>();
195        for (String opt : opts) {
196            if (useGcPattern.matcher(opt).matches()) {
197                System.out.println("removeGcOpts: removed " + opt);
198            } else {
199                optsWithoutGC.add(opt);
200            }
201        }
202        return optsWithoutGC;
203    }
204
205    /**
206     * Returns the default JTReg arguments for a jvm running a test without
207     * options that matches regular expressions in {@code filters}.
208     * This is the combination of JTReg arguments test.vm.opts and test.java.opts.
209     * @param filters Regular expressions used to filter out options.
210     * @return An array of options, or an empty array if no options.
211     */
212    public static String[] getFilteredTestJavaOpts(String... filters) {
213        String options[] = getTestJavaOpts();
214
215        if (filters.length == 0) {
216            return options;
217        }
218
219        List<String> filteredOptions = new ArrayList<String>(options.length);
220        Pattern patterns[] = new Pattern[filters.length];
221        for (int i = 0; i < filters.length; i++) {
222            patterns[i] = Pattern.compile(filters[i]);
223        }
224
225        for (String option : options) {
226            boolean matched = false;
227            for (int i = 0; i < patterns.length && !matched; i++) {
228                Matcher matcher = patterns[i].matcher(option);
229                matched = matcher.find();
230            }
231            if (!matched) {
232                filteredOptions.add(option);
233            }
234        }
235
236        return filteredOptions.toArray(new String[filteredOptions.size()]);
237    }
238
239    /**
240     * Splits a string by white space.
241     * Works like String.split(), but returns an empty array
242     * if the string is null or empty.
243     */
244    private static String[] safeSplitString(String s) {
245        if (s == null || s.trim().isEmpty()) {
246            return new String[] {};
247        }
248        return s.trim().split("\\s+");
249    }
250
251    /**
252     * @return The full command line for the ProcessBuilder.
253     */
254    public static String getCommandLine(ProcessBuilder pb) {
255        StringBuilder cmd = new StringBuilder();
256        for (String s : pb.command()) {
257            cmd.append(s).append(" ");
258        }
259        return cmd.toString();
260    }
261
262    /**
263     * Returns the free port on the local host.
264     * The function will spin until a valid port number is found.
265     *
266     * @return The port number
267     * @throws InterruptedException if any thread has interrupted the current thread
268     * @throws IOException if an I/O error occurs when opening the socket
269     */
270    public static int getFreePort() throws InterruptedException, IOException {
271        int port = -1;
272
273        while (port <= 0) {
274            Thread.sleep(100);
275
276            ServerSocket serverSocket = null;
277            try {
278                serverSocket = new ServerSocket(0);
279                port = serverSocket.getLocalPort();
280            } finally {
281                serverSocket.close();
282            }
283        }
284
285        return port;
286    }
287
288    /**
289     * Returns the name of the local host.
290     *
291     * @return The host name
292     * @throws UnknownHostException if IP address of a host could not be determined
293     */
294    public static String getHostname() throws UnknownHostException {
295        InetAddress inetAddress = InetAddress.getLocalHost();
296        String hostName = inetAddress.getHostName();
297
298        assertTrue((hostName != null && !hostName.isEmpty()),
299                "Cannot get hostname");
300
301        return hostName;
302    }
303
304    /**
305     * Uses "jcmd -l" to search for a jvm pid. This function will wait
306     * forever (until jtreg timeout) for the pid to be found.
307     * @param key Regular expression to search for
308     * @return The found pid.
309     */
310    public static int waitForJvmPid(String key) throws Throwable {
311        final long iterationSleepMillis = 250;
312        System.out.println("waitForJvmPid: Waiting for key '" + key + "'");
313        System.out.flush();
314        while (true) {
315            int pid = tryFindJvmPid(key);
316            if (pid >= 0) {
317                return pid;
318            }
319            Thread.sleep(iterationSleepMillis);
320        }
321    }
322
323    /**
324     * Searches for a jvm pid in the output from "jcmd -l".
325     *
326     * Example output from jcmd is:
327     * 12498 sun.tools.jcmd.JCmd -l
328     * 12254 /tmp/jdk8/tl/jdk/JTwork/classes/com/sun/tools/attach/Application.jar
329     *
330     * @param key A regular expression to search for.
331     * @return The found pid, or -1 if not found.
332     * @throws Exception If multiple matching jvms are found.
333     */
334    public static int tryFindJvmPid(String key) throws Throwable {
335        OutputAnalyzer output = null;
336        try {
337            JDKToolLauncher jcmdLauncher = JDKToolLauncher.create("jcmd");
338            jcmdLauncher.addToolArg("-l");
339            output = ProcessTools.executeProcess(jcmdLauncher.getCommand());
340            output.shouldHaveExitValue(0);
341
342            // Search for a line starting with numbers (pid), follwed by the key.
343            Pattern pattern = Pattern.compile("([0-9]+)\\s.*(" + key + ").*\\r?\\n");
344            Matcher matcher = pattern.matcher(output.getStdout());
345
346            int pid = -1;
347            if (matcher.find()) {
348                pid = Integer.parseInt(matcher.group(1));
349                System.out.println("findJvmPid.pid: " + pid);
350                if (matcher.find()) {
351                    throw new Exception("Found multiple JVM pids for key: " + key);
352                }
353            }
354            return pid;
355        } catch (Throwable t) {
356            System.out.println(String.format("Utils.findJvmPid(%s) failed: %s", key, t));
357            throw t;
358        }
359    }
360
361    /**
362     * Adjusts the provided timeout value for the TIMEOUT_FACTOR
363     * @param tOut the timeout value to be adjusted
364     * @return The timeout value adjusted for the value of "test.timeout.factor"
365     *         system property
366     */
367    public static long adjustTimeout(long tOut) {
368        return Math.round(tOut * Utils.TIMEOUT_FACTOR);
369    }
370
371    /**
372     * Return the contents of the named file as a single String,
373     * or null if not found.
374     * @param filename name of the file to read
375     * @return String contents of file, or null if file not found.
376     * @throws  IOException
377     *          if an I/O error occurs reading from the file or a malformed or
378     *          unmappable byte sequence is read
379     */
380    public static String fileAsString(String filename) throws IOException {
381        Path filePath = Paths.get(filename);
382        if (!Files.exists(filePath)) return null;
383        return new String(Files.readAllBytes(filePath));
384    }
385
386    private static final char[] hexArray = new char[]{'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F'};
387
388    /**
389     * Returns hex view of byte array
390     *
391     * @param bytes byte array to process
392     * @return Space separated hexadecimal string representation of bytes
393     */
394
395    public static String toHexString(byte[] bytes) {
396        char[] hexView = new char[bytes.length * 3];
397        int i = 0;
398        for (byte b : bytes) {
399            hexView[i++] = hexArray[(b >> 4) & 0x0F];
400            hexView[i++] = hexArray[b & 0x0F];
401            hexView[i++] = ' ';
402        }
403        return new String(hexView);
404    }
405
406    /**
407     * Returns {@link java.util.Random} generator initialized with particular seed.
408     * The seed could be provided via system property {@link Utils#SEED_PROPERTY_NAME}
409     * In case no seed is provided, the method uses a random number.
410     * The used seed printed to stdout.
411     * @return {@link java.util.Random} generator with particular seed.
412     */
413    public static Random getRandomInstance() {
414        if (RANDOM_GENERATOR == null) {
415            synchronized (Utils.class) {
416                if (RANDOM_GENERATOR == null) {
417                    RANDOM_GENERATOR = new Random(SEED);
418                    System.out.printf("For random generator using seed: %d%n", SEED);
419                    System.out.printf("To re-run test with same seed value please add \"-D%s=%d\" to command line.%n", SEED_PROPERTY_NAME, SEED);
420                }
421            }
422        }
423        return RANDOM_GENERATOR;
424    }
425
426    /**
427     * Returns random element of non empty collection
428     *
429     * @param <T> a type of collection element
430     * @param collection collection of elements
431     * @return random element of collection
432     * @throws IllegalArgumentException if collection is empty
433     */
434    public static <T> T getRandomElement(Collection<T> collection)
435            throws IllegalArgumentException {
436        if (collection.isEmpty()) {
437            throw new IllegalArgumentException("Empty collection");
438        }
439        Random random = getRandomInstance();
440        int elementIndex = 1 + random.nextInt(collection.size() - 1);
441        Iterator<T> iterator = collection.iterator();
442        while (--elementIndex != 0) {
443            iterator.next();
444        }
445        return iterator.next();
446    }
447
448    /**
449     * Returns random element of non empty array
450     *
451     * @param <T> a type of array element
452     * @param array array of elements
453     * @return random element of array
454     * @throws IllegalArgumentException if array is empty
455     */
456    public static <T> T getRandomElement(T[] array)
457            throws IllegalArgumentException {
458        if (array == null || array.length == 0) {
459            throw new IllegalArgumentException("Empty or null array");
460        }
461        Random random = getRandomInstance();
462        return array[random.nextInt(array.length)];
463    }
464
465    /**
466     * Wait for condition to be true
467     *
468     * @param condition, a condition to wait for
469     */
470    public static final void waitForCondition(BooleanSupplier condition) {
471        waitForCondition(condition, -1L, 100L);
472    }
473
474    /**
475     * Wait until timeout for condition to be true
476     *
477     * @param condition, a condition to wait for
478     * @param timeout a time in milliseconds to wait for condition to be true
479     * specifying -1 will wait forever
480     * @return condition value, to determine if wait was successful
481     */
482    public static final boolean waitForCondition(BooleanSupplier condition,
483            long timeout) {
484        return waitForCondition(condition, timeout, 100L);
485    }
486
487    /**
488     * Wait until timeout for condition to be true for specified time
489     *
490     * @param condition, a condition to wait for
491     * @param timeout a time in milliseconds to wait for condition to be true,
492     * specifying -1 will wait forever
493     * @param sleepTime a time to sleep value in milliseconds
494     * @return condition value, to determine if wait was successful
495     */
496    public static final boolean waitForCondition(BooleanSupplier condition,
497            long timeout, long sleepTime) {
498        long startTime = System.currentTimeMillis();
499        while (!(condition.getAsBoolean() || (timeout != -1L
500                && ((System.currentTimeMillis() - startTime) > timeout)))) {
501            try {
502                Thread.sleep(sleepTime);
503            } catch (InterruptedException e) {
504                Thread.currentThread().interrupt();
505                throw new Error(e);
506            }
507        }
508        return condition.getAsBoolean();
509    }
510
511    /**
512     * Interface same as java.lang.Runnable but with
513     * method {@code run()} able to throw any Throwable.
514     */
515    public static interface ThrowingRunnable {
516        void run() throws Throwable;
517    }
518
519    /**
520     * Filters out an exception that may be thrown by the given
521     * test according to the given filter.
522     *
523     * @param test - method that is invoked and checked for exception.
524     * @param filter - function that checks if the thrown exception matches
525     *                 criteria given in the filter's implementation.
526     * @return - exception that matches the filter if it has been thrown or
527     *           {@code null} otherwise.
528     * @throws Throwable - if test has thrown an exception that does not
529     *                     match the filter.
530     */
531    public static Throwable filterException(ThrowingRunnable test,
532            Function<Throwable, Boolean> filter) throws Throwable {
533        try {
534            test.run();
535        } catch (Throwable t) {
536            if (filter.apply(t)) {
537                return t;
538            } else {
539                throw t;
540            }
541        }
542        return null;
543    }
544
545    /**
546     * Ensures a requested class is loaded
547     * @param aClass class to load
548     */
549    public static void ensureClassIsLoaded(Class<?> aClass) {
550        if (aClass == null) {
551            throw new Error("Requested null class");
552        }
553        try {
554            Class.forName(aClass.getName(), /* initialize = */ true,
555                    ClassLoader.getSystemClassLoader());
556        } catch (ClassNotFoundException e) {
557            throw new Error("Class not found", e);
558        }
559    }
560    /**
561     * @param parent a class loader to be the parent for the returned one
562     * @return an UrlClassLoader with urls made of the 'test.class.path' jtreg
563     *         property and with the given parent
564     */
565    public static URLClassLoader getTestClassPathURLClassLoader(ClassLoader parent) {
566        URL[] urls = Arrays.stream(TEST_CLASS_PATH.split(File.pathSeparator))
567                .map(Paths::get)
568                .map(Path::toUri)
569                .map(x -> {
570                    try {
571                        return x.toURL();
572                    } catch (MalformedURLException ex) {
573                        throw new Error("Test issue. JTREG property"
574                                + " 'test.class.path'"
575                                + " is not defined correctly", ex);
576                    }
577                }).toArray(URL[]::new);
578        return new URLClassLoader(urls, parent);
579    }
580
581    /**
582     * Runs runnable and checks that it throws expected exception. If exceptionException is null it means
583     * that we expect no exception to be thrown.
584     * @param runnable what we run
585     * @param expectedException expected exception
586     */
587    public static void runAndCheckException(Runnable runnable, Class<? extends Throwable> expectedException) {
588        runAndCheckException(runnable, t -> {
589            if (t == null) {
590                if (expectedException != null) {
591                    throw new AssertionError("Didn't get expected exception " + expectedException.getSimpleName());
592                }
593            } else {
594                String message = "Got unexpected exception " + t.getClass().getSimpleName();
595                if (expectedException == null) {
596                    throw new AssertionError(message, t);
597                } else if (!expectedException.isAssignableFrom(t.getClass())) {
598                    message += " instead of " + expectedException.getSimpleName();
599                    throw new AssertionError(message, t);
600                }
601            }
602        });
603    }
604
605    /**
606     * Runs runnable and makes some checks to ensure that it throws expected exception.
607     * @param runnable what we run
608     * @param checkException a consumer which checks that we got expected exception and raises a new exception otherwise
609     */
610    public static void runAndCheckException(Runnable runnable, Consumer<Throwable> checkException) {
611        try {
612            runnable.run();
613            checkException.accept(null);
614        } catch (Throwable t) {
615            checkException.accept(t);
616        }
617    }
618
619    /**
620     * Converts to VM type signature
621     *
622     * @param type Java type to convert
623     * @return string representation of VM type
624     */
625    public static String toJVMTypeSignature(Class<?> type) {
626        if (type.isPrimitive()) {
627            if (type == boolean.class) {
628                return "Z";
629            } else if (type == byte.class) {
630                return "B";
631            } else if (type == char.class) {
632                return "C";
633            } else if (type == double.class) {
634                return "D";
635            } else if (type == float.class) {
636                return "F";
637            } else if (type == int.class) {
638                return "I";
639            } else if (type == long.class) {
640                return "J";
641            } else if (type == short.class) {
642                return "S";
643            } else if (type == void.class) {
644                return "V";
645            } else {
646                throw new Error("Unsupported type: " + type);
647            }
648        }
649        String result = type.getName().replaceAll("\\.", "/");
650        if (!type.isArray()) {
651            return "L" + result + ";";
652        }
653        return result;
654    }
655
656    public static Object[] getNullValues(Class<?>... types) {
657        Object[] result = new Object[types.length];
658        int i = 0;
659        for (Class<?> type : types) {
660            result[i++] = NULL_VALUES.get(type);
661        }
662        return result;
663    }
664    private static Map<Class<?>, Object> NULL_VALUES = new HashMap<>();
665    static {
666        NULL_VALUES.put(boolean.class, false);
667        NULL_VALUES.put(byte.class, (byte) 0);
668        NULL_VALUES.put(short.class, (short) 0);
669        NULL_VALUES.put(char.class, '\0');
670        NULL_VALUES.put(int.class, 0);
671        NULL_VALUES.put(long.class, 0L);
672        NULL_VALUES.put(float.class, 0.0f);
673        NULL_VALUES.put(double.class, 0.0d);
674    }
675
676    /**
677     * Returns mandatory property value
678     * @param propName is a name of property to request
679     * @return a String with requested property value
680     */
681    public static String getMandatoryProperty(String propName) {
682        Objects.requireNonNull(propName, "Requested null property");
683        String prop = System.getProperty(propName);
684        Objects.requireNonNull(prop,
685                String.format("A mandatory property '%s' isn't set", propName));
686        return prop;
687    }
688
689    /*
690     * Run uname with specified arguments.
691     */
692    public static OutputAnalyzer uname(String... args) throws Throwable {
693        String[] cmds = new String[args.length + 1];
694        cmds[0] = "uname";
695        System.arraycopy(args, 0, cmds, 1, args.length);
696        return ProcessTools.executeCommand(cmds);
697    }
698
699    /*
700     * Returns the system distro.
701     */
702    public static String distro() {
703        try {
704            return uname("-v").asLines().get(0);
705        } catch (Throwable t) {
706            throw new RuntimeException("Failed to determine distro.", t);
707        }
708    }
709
710    // This method is intended to be called from a jtreg test.
711    // It will identify the name of the test by means of stack walking.
712    // It can handle both jtreg tests and a testng tests wrapped inside jtreg tests.
713    // For jtreg tests the name of the test will be searched by stack-walking
714    // until the method main() is found; the class containing that method is the
715    // main test class and will be returned as the name of the test.
716    // Special handling is used for testng tests.
717    public static String getTestName() {
718        String result = null;
719        // If we are using testng, then we should be able to load the "Test" annotation.
720        Class testClassAnnotation;
721
722        try {
723            testClassAnnotation = Class.forName("org.testng.annotations.Test");
724        } catch (ClassNotFoundException e) {
725            testClassAnnotation = null;
726        }
727
728        StackTraceElement[] elms = (new Throwable()).getStackTrace();
729        for (StackTraceElement n: elms) {
730            String className = n.getClassName();
731
732            // If this is a "main" method, then use its class name, but only
733            // if we are not using testng.
734            if (testClassAnnotation == null && "main".equals(n.getMethodName())) {
735                result = className;
736                break;
737            }
738
739            // If this is a testng test, the test will have no "main" method. We can
740            // detect a testng test class by looking for the org.testng.annotations.Test
741            // annotation. If present, then use the name of this class.
742            if (testClassAnnotation != null) {
743                try {
744                    Class c = Class.forName(className);
745                    if (c.isAnnotationPresent(testClassAnnotation)) {
746                        result = className;
747                        break;
748                    }
749                } catch (ClassNotFoundException e) {
750                    throw new RuntimeException("Unexpected exception: " + e, e);
751                }
752            }
753        }
754
755        if (result == null) {
756            throw new RuntimeException("Couldn't find main test class in stack trace");
757        }
758
759        return result;
760    }
761
762}
763
764