Random() public static méthode

Access to the current RandomizedContext's Random instance. It is safe to use this method from multiple threads, etc., but it should be called while within a runner's scope (so no static initializers). The returned Random instance will be different when this method is called inside a BeforeClass hook (static suite scope) and within Before/ After hooks or test methods.

The returned instance must not be shared with other threads or cross a single scope's boundary. For example, a Random acquired within a test method shouldn't be reused for another test case.

There is an overhead connected with getting the Random for a particular context and thread. It is better to cache the Random locally if tight loops with multiple invocations are present or create a derivative local Random for millions of calls like this:

 Random random = new Random(random().nextLong()); // tight loop with many invocations. 
public static Random ( ) : Random
Résultat Random
Exemple #1
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        public override void Before(LuceneTestCase testInstance)
        {
            // if verbose: print some debugging stuff about which codecs are loaded.
            if (LuceneTestCase.VERBOSE)
            {
                ICollection <string> codecs = Codec.AvailableCodecs();
                foreach (string codec in codecs)
                {
                    Console.WriteLine("Loaded codec: '" + codec + "': " + Codec.ForName(codec).GetType().Name);
                }

                ICollection <string> postingsFormats = PostingsFormat.AvailablePostingsFormats();
                foreach (string postingsFormat in postingsFormats)
                {
                    Console.WriteLine("Loaded postingsFormat: '" + postingsFormat + "': " + PostingsFormat.ForName(postingsFormat).GetType().Name);
                }
            }

            savedInfoStream = InfoStream.Default;
            Random random = LuceneTestCase.Random();
            bool   v      = random.NextBoolean();

            if (LuceneTestCase.INFOSTREAM)
            {
                InfoStream.Default = new ThreadNameFixingPrintStreamInfoStream(Console.Out);
            }
            else if (v)
            {
                InfoStream.Default = new NullInfoStream();
            }

            Type targetClass = testInstance.GetType();

            avoidCodecs = new HashSet <string>();
            var suppressCodecsAttribute = targetClass.GetTypeInfo().GetCustomAttribute <LuceneTestCase.SuppressCodecsAttribute>();

            if (suppressCodecsAttribute != null)
            {
                avoidCodecs.AddAll(suppressCodecsAttribute.Value);
            }

            // set back to default
            LuceneTestCase.OLD_FORMAT_IMPERSONATION_IS_ACTIVE = false;

            savedCodec = Codec.Default;
            int randomVal = random.Next(10);

            if ("Lucene3x".Equals(LuceneTestCase.TEST_CODEC, StringComparison.Ordinal) || ("random".Equals(LuceneTestCase.TEST_CODEC, StringComparison.Ordinal) &&
                                                                                           "random".Equals(LuceneTestCase.TEST_POSTINGSFORMAT, StringComparison.Ordinal) &&
                                                                                           "random".Equals(LuceneTestCase.TEST_DOCVALUESFORMAT, StringComparison.Ordinal) &&
                                                                                           randomVal == 3 &&
                                                                                           !ShouldAvoidCodec("Lucene3x"))) // preflex-only setup
            {
                codec = Codec.ForName("Lucene3x");
                Debug.Assert((codec is PreFlexRWCodec), "fix your ICodecFactory to scan Lucene.Net.Tests before Lucene.Net.TestFramework");
                LuceneTestCase.OLD_FORMAT_IMPERSONATION_IS_ACTIVE = true;
            }
            else if ("Lucene40".Equals(LuceneTestCase.TEST_CODEC, StringComparison.Ordinal) || ("random".Equals(LuceneTestCase.TEST_CODEC, StringComparison.Ordinal) &&
                                                                                                "random".Equals(LuceneTestCase.TEST_POSTINGSFORMAT, StringComparison.Ordinal) &&
                                                                                                randomVal == 0 &&
                                                                                                !ShouldAvoidCodec("Lucene40"))) // 4.0 setup
            {
                codec = Codec.ForName("Lucene40");
                LuceneTestCase.OLD_FORMAT_IMPERSONATION_IS_ACTIVE = true;
                Debug.Assert((codec is Lucene40RWCodec), "fix your ICodecFactory to scan Lucene.Net.Tests before Lucene.Net.TestFramework");
                Debug.Assert((PostingsFormat.ForName("Lucene40") is Lucene40RWPostingsFormat), "fix your IPostingsFormatFactory to scan Lucene.Net.Tests before Lucene.Net.TestFramework");
            }
            else if ("Lucene41".Equals(LuceneTestCase.TEST_CODEC, StringComparison.Ordinal) || ("random".Equals(LuceneTestCase.TEST_CODEC, StringComparison.Ordinal) &&
                                                                                                "random".Equals(LuceneTestCase.TEST_POSTINGSFORMAT, StringComparison.Ordinal) &&
                                                                                                "random".Equals(LuceneTestCase.TEST_DOCVALUESFORMAT, StringComparison.Ordinal) &&
                                                                                                randomVal == 1 &&
                                                                                                !ShouldAvoidCodec("Lucene41")))
            {
                codec = Codec.ForName("Lucene41");
                LuceneTestCase.OLD_FORMAT_IMPERSONATION_IS_ACTIVE = true;
                Debug.Assert((codec is Lucene41RWCodec), "fix your ICodecFactory to scan Lucene.Net.Tests before Lucene.Net.TestFramework");
            }
            else if ("Lucene42".Equals(LuceneTestCase.TEST_CODEC, StringComparison.Ordinal) || ("random".Equals(LuceneTestCase.TEST_CODEC, StringComparison.Ordinal) &&
                                                                                                "random".Equals(LuceneTestCase.TEST_POSTINGSFORMAT, StringComparison.Ordinal) &&
                                                                                                "random".Equals(LuceneTestCase.TEST_DOCVALUESFORMAT, StringComparison.Ordinal) &&
                                                                                                randomVal == 2 &&
                                                                                                !ShouldAvoidCodec("Lucene42")))
            {
                codec = Codec.ForName("Lucene42");
                LuceneTestCase.OLD_FORMAT_IMPERSONATION_IS_ACTIVE = true;
                Debug.Assert((codec is Lucene42RWCodec), "fix your ICodecFactory to scan Lucene.Net.Tests before Lucene.Net.TestFramework");
            }
            else if ("Lucene45".Equals(LuceneTestCase.TEST_CODEC, StringComparison.Ordinal) || ("random".Equals(LuceneTestCase.TEST_CODEC, StringComparison.Ordinal) &&
                                                                                                "random".Equals(LuceneTestCase.TEST_POSTINGSFORMAT, StringComparison.Ordinal) &&
                                                                                                "random".Equals(LuceneTestCase.TEST_DOCVALUESFORMAT, StringComparison.Ordinal) &&
                                                                                                randomVal == 5 &&
                                                                                                !ShouldAvoidCodec("Lucene45")))
            {
                codec = Codec.ForName("Lucene45");
                LuceneTestCase.OLD_FORMAT_IMPERSONATION_IS_ACTIVE = true;
                Debug.Assert((codec is Lucene45RWCodec), "fix your ICodecFactory to scan Lucene.Net.Tests before Lucene.Net.TestFramework");
            }
            else if (("random".Equals(LuceneTestCase.TEST_POSTINGSFORMAT, StringComparison.Ordinal) == false) ||
                     ("random".Equals(LuceneTestCase.TEST_DOCVALUESFORMAT, StringComparison.Ordinal) == false))
            {
                // the user wired postings or DV: this is messy
                // refactor into RandomCodec....

                PostingsFormat format;
                if ("random".Equals(LuceneTestCase.TEST_POSTINGSFORMAT, StringComparison.Ordinal))
                {
                    format = PostingsFormat.ForName("Lucene41");
                }
                else if ("MockRandom".Equals(LuceneTestCase.TEST_POSTINGSFORMAT, StringComparison.Ordinal))
                {
                    format = new MockRandomPostingsFormat(new Random(random.Next()));
                }
                else
                {
                    format = PostingsFormat.ForName(LuceneTestCase.TEST_POSTINGSFORMAT);
                }

                DocValuesFormat dvFormat;
                if ("random".Equals(LuceneTestCase.TEST_DOCVALUESFORMAT, StringComparison.Ordinal))
                {
                    dvFormat = DocValuesFormat.ForName("Lucene45");
                }
                else
                {
                    dvFormat = DocValuesFormat.ForName(LuceneTestCase.TEST_DOCVALUESFORMAT);
                }

                codec = new Lucene46CodecAnonymousInnerClassHelper(this, format, dvFormat);
            }
            else if ("SimpleText".Equals(LuceneTestCase.TEST_CODEC, StringComparison.Ordinal) ||
                     ("random".Equals(LuceneTestCase.TEST_CODEC, StringComparison.Ordinal) && randomVal == 9 && LuceneTestCase.Rarely(random) && !ShouldAvoidCodec("SimpleText")))
            {
                codec = new SimpleTextCodec();
            }
            else if ("CheapBastard".Equals(LuceneTestCase.TEST_CODEC, StringComparison.Ordinal) ||
                     ("random".Equals(LuceneTestCase.TEST_CODEC, StringComparison.Ordinal) && randomVal == 8 && !ShouldAvoidCodec("CheapBastard") && !ShouldAvoidCodec("Lucene41")))
            {
                // we also avoid this codec if Lucene41 is avoided, since thats the postings format it uses.
                codec = new CheapBastardCodec();
            }
            else if ("Asserting".Equals(LuceneTestCase.TEST_CODEC, StringComparison.Ordinal) ||
                     ("random".Equals(LuceneTestCase.TEST_CODEC, StringComparison.Ordinal) && randomVal == 6 && !ShouldAvoidCodec("Asserting")))
            {
                codec = new AssertingCodec();
            }
            else if ("Compressing".Equals(LuceneTestCase.TEST_CODEC, StringComparison.Ordinal) ||
                     ("random".Equals(LuceneTestCase.TEST_CODEC, StringComparison.Ordinal) && randomVal == 5 && !ShouldAvoidCodec("Compressing")))
            {
                codec = CompressingCodec.RandomInstance(random);
            }
            else if (!"random".Equals(LuceneTestCase.TEST_CODEC, StringComparison.Ordinal))
            {
                codec = Codec.ForName(LuceneTestCase.TEST_CODEC);
            }
            else if ("random".Equals(LuceneTestCase.TEST_POSTINGSFORMAT, StringComparison.Ordinal))
            {
                codec = new RandomCodec(random, avoidCodecs);
            }
            else
            {
                Debug.Assert(false);
            }
            Codec.Default = codec;

            // Initialize locale/ timezone.
            string testLocale   = SystemProperties.GetProperty("tests.locale", "random");
            string testTimeZone = SystemProperties.GetProperty("tests.timezone", "random");

            // Always pick a random one for consistency (whether tests.locale was specified or not).
            savedLocale = CultureInfo.CurrentCulture;
            CultureInfo randomLocale = LuceneTestCase.RandomLocale(random);

            locale = testLocale.Equals("random", StringComparison.Ordinal) ? randomLocale : LuceneTestCase.LocaleForName(testLocale);
#if NETSTANDARD
            CultureInfo.CurrentCulture = locale;
#else
            Thread.CurrentThread.CurrentCulture = locale;
#endif

            // TimeZone.getDefault will set user.timezone to the default timezone of the user's locale.
            // So store the original property value and restore it at end.
            restoreProperties["user.timezone"] = SystemProperties.GetProperty("user.timezone");
            savedTimeZone = testInstance.TimeZone;
            TimeZoneInfo randomTimeZone = LuceneTestCase.RandomTimeZone(random);
            timeZone = testTimeZone.Equals("random", StringComparison.Ordinal) ? randomTimeZone : TimeZoneInfo.FindSystemTimeZoneById(testTimeZone);
            //TimeZone.Default = TimeZone; // LUCENENET NOTE: There doesn't seem to be an equivalent to this, but I don't think we need it.

            similarity = random.NextBoolean() ? (Similarity) new DefaultSimilarity() : new RandomSimilarityProvider(random);

            // Check codec restrictions once at class level.
            try
            {
                CheckCodecRestrictions(codec);
            }
            catch (Exception e)
            {
                Console.Error.WriteLine("NOTE: " + e.Message + " Suppressed codecs: " + Arrays.ToString(avoidCodecs.ToArray()));
                throw e;
            }
        }