classlib: update RandomGenerator implementation (#743)

classlib/src/main/java/org/teavm/classlib/impl/RandomUtils.java

@@ -0,0 +1,94 @@
+/*
+ *  Copyright 2023 ihromant.
+ *
+ *  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.teavm.classlib.impl;
+
+import java.util.function.DoubleSupplier;
+
+public class RandomUtils {
+    public static void checkStreamSize(long streamSize) {
+        if (streamSize < 0L) {
+            throw new IllegalArgumentException();
+        }
+    }
+
+    public static void checkBound(float bound) {
+        if (!(bound > 0.0 && bound < Float.POSITIVE_INFINITY)) {
+            throw new IllegalArgumentException();
+        }
+    }
+
+    public static void checkBound(double bound) {
+        if (!(bound > 0.0 && bound < Double.POSITIVE_INFINITY)) {
+            throw new IllegalArgumentException();
+        }
+    }
+
+    public static void checkBound(int bound) {
+        if (bound <= 0) {
+            throw new IllegalArgumentException();
+        }
+    }
+
+    public static void checkBound(long bound) {
+        if (bound <= 0) {
+            throw new IllegalArgumentException();
+        }
+    }
+
+    public static void checkRange(float origin, float bound) {
+        if (!(origin < bound && bound - origin < Float.POSITIVE_INFINITY)) {
+            throw new IllegalArgumentException();
+        }
+    }
+
+    public static void checkRange(double origin, double bound) {
+        if (!(origin < bound && bound - origin < Double.POSITIVE_INFINITY)) {
+            throw new IllegalArgumentException();
+        }
+    }
+
+    public static void checkRange(int origin, int bound) {
+        if (origin >= bound) {
+            throw new IllegalArgumentException();
+        }
+    }
+
+    public static void checkRange(long origin, long bound) {
+        if (origin >= bound) {
+            throw new IllegalArgumentException();
+        }
+    }
+
+    public static double[] pairGaussian(DoubleSupplier rng) {
+        /*
+         * This implementation uses the polar method to generate two gaussian
+         * values at a time. One is returned, and the other is stored to be returned
+         * next time.
+         */
+        double v1;
+        double v2;
+        double s;
+        do {
+            v1 = 2 * rng.getAsDouble() - 1;
+            v2 = 2 * rng.getAsDouble() - 1;
+            s = v1 * v1 + v2 * v2;
+        } while (s >= 1 || s == 0);
+
+        double m = StrictMath.sqrt(-2 * StrictMath.log(s) / s);
+
+        return new double[] { v1 * m, v2 * m };
+    }
+}

classlib/src/main/java/org/teavm/classlib/java/util/TRandom.java

@@ -15,32 +15,23 @@
  */
 package org.teavm.classlib.java.util;
 
-import java.util.function.DoublePredicate;
-import java.util.function.IntPredicate;
-import java.util.function.LongPredicate;
 import org.teavm.backend.wasm.runtime.WasmSupport;
 import org.teavm.classlib.PlatformDetector;
+import org.teavm.classlib.impl.RandomUtils;
 import org.teavm.classlib.java.io.TSerializable;
-import org.teavm.classlib.java.lang.TMath;
 import org.teavm.classlib.java.lang.TObject;
-import org.teavm.classlib.java.util.stream.TDoubleStream;
+import org.teavm.classlib.java.util.random.TRandomGenerator;
-import org.teavm.classlib.java.util.stream.TIntStream;
-import org.teavm.classlib.java.util.stream.TLongStream;
-import org.teavm.classlib.java.util.stream.doubleimpl.TSimpleDoubleStreamImpl;
-import org.teavm.classlib.java.util.stream.intimpl.TSimpleIntStreamImpl;
-import org.teavm.classlib.java.util.stream.longimpl.TSimpleLongStreamImpl;
 import org.teavm.interop.Import;
 import org.teavm.interop.Unmanaged;
 import org.teavm.jso.JSBody;
 
-public class TRandom extends TObject implements TSerializable {
+public class TRandom extends TObject implements TRandomGenerator, TSerializable {
-
     /** A stored gaussian value for nextGaussian() */
     private double storedGaussian;
-    
+
     /** Whether storedGuassian value is valid */
     private boolean haveStoredGaussian;
-    
+
     public TRandom() {
     }
 
@@ -50,24 +41,12 @@ public class TRandom extends TObject implements TSerializable {
     public void setSeed(@SuppressWarnings("unused") long seed) {
     }
 
-    protected int next(int bits) {
+    @Override
-        if (bits == 32) {
-            return (int) (nextDouble() * ((1L << 32) - 1) + Integer.MIN_VALUE);
-        } else {
-            return (int) (nextDouble() * (1L << TMath.min(32, bits)));
-        }
-    }
-
-    public void nextBytes(byte[] bytes) {
-        for (int i = 0; i < bytes.length; ++i) {
-            bytes[i] = (byte) next(8);
-        }
-    }
-
     public int nextInt() {
-        return next(32);
+        return (int) (0x1.0p+32 * nextDouble() + Integer.MIN_VALUE);
     }
 
+    @Override
     public int nextInt(int n) {
         if (n <= 0) {
             throw new IllegalArgumentException();
@@ -75,73 +54,17 @@ public class TRandom extends TObject implements TSerializable {
         return (int) (nextDouble() * n);
     }
 
-    public int nextInt(int origin, int bound) {
+    @Override
-        if (origin >= bound) {
-            throw new IllegalArgumentException();
-        }
-        int range = bound - origin;
-        if (range > 0) {
-            return nextInt(range) + origin;
-        } else {
-            while (true) {
-                int value = nextInt();
-                if (value >= origin && value < bound) {
-                    return value;
-                }
-            }
-        }
-    }
-
     public long nextLong() {
         return ((long) nextInt() << 32) | nextInt();
     }
 
-    public long nextLong(long bound) {
+    @Override
-        if (bound <= 0) {
-            throw new IllegalArgumentException();
-        }
-        while (true) {
-            long value = nextLong();
-            long result = value % bound;
-            if (value - result + (bound - 1) < 0) {
-                return result;
-            }
-        }
-    }
-
-    public long nextLong(long origin, long bound) {
-        if (origin >= bound) {
-            throw new IllegalArgumentException();
-        }
-        long range = bound - origin;
-        if (range > 0) {
-            return nextLong(range) + origin;
-        } else {
-            while (true) {
-                long value = nextLong();
-                if (value >= origin && value < bound) {
-                    return value;
-                }
-            }
-        }
-    }
-
-    public boolean nextBoolean() {
-        return nextInt() % 2 == 0;
-    }
-
     public float nextFloat() {
         return (float) nextDouble();
     }
 
-    public float nextFloat(float bound) {
+    @Override
-        return (float) nextDouble(bound);
-    }
-
-    public float nextFloat(float origin, float bound) {
-        return (float) nextDouble(origin, bound);
-    }
-
     public double nextDouble() {
         if (PlatformDetector.isC()) {
             return crand();
@@ -152,24 +75,6 @@ public class TRandom extends TObject implements TSerializable {
         }
     }
 
-    public double nextDouble(double bound) {
-        if (bound <= 0) {
-            throw new IllegalArgumentException();
-        }
-        double value = nextDouble() * bound;
-        if (value == bound) {
-            value = Math.nextDown(value);
-        }
-        return value;
-    }
-
-    public double nextDouble(double origin, double bound) {
-        if (origin >= bound) {
-            throw new IllegalArgumentException();
-        }
-        return origin + nextDouble(bound - origin);
-    }
-
     @Import(name = "teavm_rand")
     @Unmanaged
     private static native double crand();
@@ -178,329 +83,27 @@ public class TRandom extends TObject implements TSerializable {
      * Generate a random number with Gaussian distribution:
      * centered around 0 with a standard deviation of 1.0.
      */
+    @Override
     public double nextGaussian() {
-
         /*
          * This implementation uses the polar method to generate two gaussian
          * values at a time. One is returned, and the other is stored to be returned
          * next time.
          */
-
         if (haveStoredGaussian) {
             haveStoredGaussian = false;
             return storedGaussian;
         }
 
-        double v1;
+        double[] pair = RandomUtils.pairGaussian(this::nextDouble);
-        double v2;
-        double s;
-        do {
-            v1 = 2 * nextDouble() - 1;
-            v2 = 2 * nextDouble() - 1;
-            s = v1 * v1 + v2 * v2;
-        } while (s >= 1 || s == 0);
-
-        double m = StrictMath.sqrt(-2 * StrictMath.log(s) / s);
-        storedGaussian = v2 * m;
         haveStoredGaussian = true;
+        storedGaussian = pair[1];
 
-        return v1 * m;
+        return pair[0];
     }
 
     @JSBody(script = "return Math.random();")
     @Import(module = "teavmMath", name = "random")
     @Unmanaged
     private static native double random();
-
-    public TIntStream ints(long streamSize) {
-        if (streamSize < 0) {
-            throw new IllegalArgumentException();
-        }
-        return new TSimpleIntStreamImpl() {
-            private long remaining = streamSize;
-
-            @Override
-            public boolean next(IntPredicate consumer) {
-                while (remaining > 0) {
-                    --remaining;
-                    if (!consumer.test(nextInt())) {
-                        return true;
-                    }
-                }
-                return false;
-            }
-        };
-    }
-
-    public TIntStream ints() {
-        return new TSimpleIntStreamImpl() {
-            @Override
-            public boolean next(IntPredicate consumer) {
-                while (consumer.test(nextInt())) {
-                    // go on
-                }
-                return true;
-            }
-        };
-    }
-
-    public TIntStream ints(long streamSize, int randomNumberOrigin, int randomNumberBound) {
-        if (streamSize < 0 || randomNumberOrigin >= randomNumberBound) {
-            throw new IllegalArgumentException();
-        }
-
-        int range = randomNumberBound - randomNumberOrigin;
-        if (range > 0) {
-            return new TSimpleIntStreamImpl() {
-                long remaining = streamSize;
-
-                @Override
-                public boolean next(IntPredicate consumer) {
-                    while (remaining > 0) {
-                        --remaining;
-                        if (!consumer.test(nextInt(range) + randomNumberOrigin)) {
-                            return true;
-                        }
-                    }
-                    return false;
-                }
-            };
-        } else {
-            return new TSimpleIntStreamImpl() {
-                long remaining = streamSize;
-
-                @Override
-                public boolean next(IntPredicate consumer) {
-                    while (remaining > 0) {
-                        --remaining;
-                        int n;
-                        do {
-                            n = nextInt();
-                        } while (n < randomNumberOrigin || n >= randomNumberBound);
-                        if (!consumer.test(n)) {
-                            return true;
-                        }
-                    }
-                    return false;
-                }
-            };
-        }
-    }
-
-    public TIntStream ints(int randomNumberOrigin, int randomNumberBound) {
-        if (randomNumberOrigin >= randomNumberBound) {
-            throw new IllegalArgumentException();
-        }
-
-        int range = randomNumberBound - randomNumberOrigin;
-        if (range > 0) {
-            return new TSimpleIntStreamImpl() {
-                @Override
-                public boolean next(IntPredicate consumer) {
-                    while (true) {
-                        if (!consumer.test(nextInt(range) + randomNumberOrigin)) {
-                            return true;
-                        }
-                    }
-                }
-            };
-        } else {
-            return new TSimpleIntStreamImpl() {
-                @Override
-                public boolean next(IntPredicate consumer) {
-                    while (true) {
-                        int n;
-                        do {
-                            n = nextInt();
-                        } while (n < randomNumberOrigin || n >= randomNumberBound);
-                        if (!consumer.test(n)) {
-                            return true;
-                        }
-                    }
-                }
-            };
-        }
-    }
-
-    public TLongStream longs(long streamSize) {
-        if (streamSize < 0) {
-            throw new IllegalArgumentException();
-        }
-        return new TSimpleLongStreamImpl() {
-            private long remaining = streamSize;
-
-            @Override
-            public boolean next(LongPredicate consumer) {
-                while (remaining > 0) {
-                    --remaining;
-                    if (!consumer.test(nextLong())) {
-                        return true;
-                    }
-                }
-                return false;
-            }
-        };
-    }
-
-    public TLongStream longs() {
-        return new TSimpleLongStreamImpl() {
-            @Override
-            public boolean next(LongPredicate consumer) {
-                while (consumer.test(nextLong())) {
-                    // go on
-                }
-                return true;
-            }
-        };
-    }
-
-    public TLongStream longs(long streamSize, long randomNumberOrigin, long randomNumberBound) {
-        if (streamSize < 0 || randomNumberOrigin >= randomNumberBound) {
-            throw new IllegalArgumentException();
-        }
-
-        long range = randomNumberBound - randomNumberOrigin;
-        if (range > 0) {
-            return new TSimpleLongStreamImpl() {
-                long remaining = streamSize;
-
-                @Override
-                public boolean next(LongPredicate consumer) {
-                    while (remaining > 0) {
-                        --remaining;
-                        if (!consumer.test(nextLong(range) + randomNumberOrigin)) {
-                            return true;
-                        }
-                    }
-                    return false;
-                }
-            };
-        } else {
-            return new TSimpleLongStreamImpl() {
-                long remaining = streamSize;
-
-                @Override
-                public boolean next(LongPredicate consumer) {
-                    while (remaining > 0) {
-                        --remaining;
-                        long n;
-                        do {
-                            n = nextLong();
-                        } while (n < randomNumberOrigin || n >= randomNumberBound);
-                        if (!consumer.test(n)) {
-                            return true;
-                        }
-                    }
-                    return false;
-                }
-            };
-        }
-    }
-
-    public TLongStream longs(long randomNumberOrigin, long randomNumberBound) {
-        if (randomNumberOrigin >= randomNumberBound) {
-            throw new IllegalArgumentException();
-        }
-
-        long range = randomNumberBound - randomNumberOrigin;
-        if (range > 0) {
-            return new TSimpleLongStreamImpl() {
-                @Override
-                public boolean next(LongPredicate consumer) {
-                    while (true) {
-                        if (!consumer.test(nextLong(range) + randomNumberOrigin)) {
-                            return true;
-                        }
-                    }
-                }
-            };
-        } else {
-            return new TSimpleLongStreamImpl() {
-                @Override
-                public boolean next(LongPredicate consumer) {
-                    while (true) {
-                        long n;
-                        do {
-                            n = nextLong();
-                        } while (n < randomNumberOrigin || n >= randomNumberBound);
-                        if (!consumer.test(n)) {
-                            return true;
-                        }
-                    }
-                }
-            };
-        }
-    }
-
-    public TDoubleStream doubles(long streamSize) {
-        if (streamSize < 0) {
-            throw new IllegalArgumentException();
-        }
-        return new TSimpleDoubleStreamImpl() {
-            private long remaining = streamSize;
-
-            @Override
-            public boolean next(DoublePredicate consumer) {
-                while (remaining > 0) {
-                    --remaining;
-                    if (!consumer.test(nextDouble())) {
-                        return true;
-                    }
-                }
-                return false;
-            }
-        };
-    }
-
-    public TDoubleStream doubles() {
-        return new TSimpleDoubleStreamImpl() {
-            @Override
-            public boolean next(DoublePredicate consumer) {
-                while (consumer.test(nextDouble())) {
-                    // go on
-                }
-                return true;
-            }
-        };
-    }
-
-    public TDoubleStream doubles(long streamSize, double randomNumberOrigin, double randomNumberBound) {
-        if (streamSize < 0 || randomNumberOrigin >= randomNumberBound) {
-            throw new IllegalArgumentException();
-        }
-
-        double range = randomNumberBound - randomNumberOrigin;
-        return new TSimpleDoubleStreamImpl() {
-            long remaining = streamSize;
-
-            @Override
-            public boolean next(DoublePredicate consumer) {
-                while (remaining > 0) {
-                    --remaining;
-                    if (!consumer.test(nextDouble() * range + randomNumberOrigin)) {
-                        return true;
-                    }
-                }
-                return false;
-            }
-        };
-    }
-
-    public TDoubleStream doubles(double randomNumberOrigin, double randomNumberBound) {
-        if (randomNumberOrigin >= randomNumberBound) {
-            throw new IllegalArgumentException();
-        }
-
-        double range = randomNumberBound - randomNumberOrigin;
-        return new TSimpleDoubleStreamImpl() {
-            @Override
-            public boolean next(DoublePredicate consumer) {
-                while (true) {
-                    if (!consumer.test(nextDouble() * range + randomNumberOrigin)) {
-                        return true;
-                    }
-                }
-            }
-        };
-    }
 }

classlib/src/main/java/org/teavm/classlib/java/util/random/TRandomGenerator.java

@@ -0,0 +1,223 @@
+/*
+ *  Copyright 2023 ihromant.
+ *
+ *  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.teavm.classlib.java.util.random;
+
+import org.teavm.classlib.impl.RandomUtils;
+import org.teavm.classlib.java.util.stream.TDoubleStream;
+import org.teavm.classlib.java.util.stream.TIntStream;
+import org.teavm.classlib.java.util.stream.TLongStream;
+
+public interface TRandomGenerator {
+    default boolean isDeprecated() {
+        return false;
+    }
+
+    default TDoubleStream doubles() {
+        return TDoubleStream.generate(this::nextDouble);
+    }
+
+    default TDoubleStream doubles(double origin, double bound) {
+        RandomUtils.checkRange(origin, bound);
+        return TDoubleStream.generate(() -> nextDouble(origin, bound));
+    }
+
+    default TDoubleStream doubles(long streamSize) {
+        RandomUtils.checkStreamSize(streamSize);
+        return doubles().limit(streamSize);
+    }
+
+    default TDoubleStream doubles(long streamSize, double origin,
+            double bound) {
+        RandomUtils.checkStreamSize(streamSize);
+        RandomUtils.checkRange(origin, bound);
+        return doubles(origin, bound).limit(streamSize);
+    }
+
+    default TIntStream ints() {
+        return TIntStream.generate(this::nextInt);
+    }
+
+    default TIntStream ints(int origin, int bound) {
+        RandomUtils.checkRange(origin, bound);
+        return TIntStream.generate(() -> nextInt(origin, bound));
+    }
+
+    default TIntStream ints(long streamSize) {
+        RandomUtils.checkStreamSize(streamSize);
+        return ints().limit(streamSize);
+    }
+
+    default TIntStream ints(long streamSize, int origin,
+            int bound) {
+        RandomUtils.checkStreamSize(streamSize);
+        RandomUtils.checkRange(origin, bound);
+        return ints(origin, bound).limit(streamSize);
+    }
+
+    default TLongStream longs() {
+        return TLongStream.generate(this::nextLong);
+    }
+
+    default TLongStream longs(long origin, long bound) {
+        RandomUtils.checkRange(origin, bound);
+        return TLongStream.generate(() -> nextLong(origin, bound));
+    }
+
+    default TLongStream longs(long streamSize) {
+        RandomUtils.checkStreamSize(streamSize);
+        return longs().limit(streamSize);
+    }
+
+    default TLongStream longs(long streamSize, long origin,
+            long bound) {
+        RandomUtils.checkStreamSize(streamSize);
+        RandomUtils.checkRange(origin, bound);
+        return longs(origin, bound).limit(streamSize);
+    }
+
+    default boolean nextBoolean() {
+        return nextInt() < 0;
+    }
+
+    default void nextBytes(byte[] bytes) {
+        if (bytes.length == 0) {
+            return;
+        }
+        int len = (bytes.length - 1) / Integer.BYTES + 1;
+        for (int i = 0; i < len; i++) {
+            int rnd = nextInt();
+            for (int j = 0; j < Integer.BYTES; j++) {
+                int idx = Integer.BYTES * i + j;
+                if (idx < bytes.length) {
+                    bytes[idx] = (byte) (0xFF & (rnd >> (i * Byte.SIZE)));
+                }
+            }
+        }
+    }
+
+    default float nextFloat() {
+        return (nextInt() >>> 8) * 0x1.0p-24f;
+    }
+
+    default float nextFloat(float bound) {
+        RandomUtils.checkBound(bound);
+        float res = nextFloat() * bound;
+        if (res >= bound) {
+            res = Math.nextDown(bound);
+        }
+        return res;
+    }
+
+    default float nextFloat(float origin, float bound) {
+        RandomUtils.checkRange(origin, bound);
+        float res = nextFloat() * (bound - origin) + origin;
+        if (res >= bound) {
+            res = Math.nextAfter(bound, origin);
+        }
+        return res;
+    }
+
+    default double nextDouble() {
+        return (nextLong() >>> 11) * 0x1.0p-53;
+    }
+
+    default double nextDouble(double bound) {
+        RandomUtils.checkBound(bound);
+        double res = nextDouble() * bound;
+        if (res >= bound) {
+            res = Math.nextDown(bound);
+        }
+        return res;
+    }
+
+    default double nextDouble(double origin, double bound) {
+        RandomUtils.checkRange(origin, bound);
+        double res = nextDouble() * (bound - origin) + origin;
+        if (res >= bound) {
+            res = Math.nextAfter(bound, origin);
+        }
+        return res;
+    }
+
+    default int nextInt() {
+        return (int) (nextLong() >>> 32);
+    }
+
+    default int nextInt(int bound) {
+        RandomUtils.checkBound(bound);
+        int mask = (Integer.highestOneBit(bound) << 1) - 1;
+        while (true) {
+            int res = nextInt() & mask;
+            if (res < bound) {
+                return res;
+            }
+        }
+    }
+
+    default int nextInt(int origin, int bound) {
+        RandomUtils.checkRange(origin, bound);
+        int range = bound - origin;
+        if (range > 0) {
+            return nextInt(range) + origin;
+        } else {
+            while (true) {
+                int res = nextInt();
+                if (res >= origin && res < bound) {
+                    return res;
+                }
+            }
+        }
+    }
+
+    long nextLong();
+
+    default long nextLong(long bound) {
+        RandomUtils.checkBound(bound);
+        long mask = (Long.highestOneBit(bound) << 1) - 1;
+        while (true) {
+            long res = nextLong() & mask;
+            if (res < bound) {
+                return res;
+            }
+        }
+    }
+
+    default long nextLong(long origin, long bound) {
+        RandomUtils.checkRange(origin, bound);
+        long range = bound - origin;
+        if (range > 0) {
+            return nextLong(range) + origin;
+        } else {
+            while (true) {
+                long res = nextLong();
+                if (res >= origin && res < bound) {
+                    return res;
+                }
+            }
+        }
+    }
+
+    default double nextGaussian() {
+        return RandomUtils.pairGaussian(this::nextDouble)[0];
+    }
+
+    default double nextGaussian(double mean, double stddev) {
+        if (stddev < 0.0) {
+            throw new IllegalArgumentException();
+        }
+        return mean + stddev * nextGaussian();
+    }
+}

tests/src/test/java/org/teavm/classlib/java/util/RandomTest.java

@@ -0,0 +1,171 @@
+/*
+ *  Copyright 2023 ihromant.
+ *
+ *  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.teavm.classlib.java.util;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.fail;
+import java.util.Arrays;
+import java.util.Random;
+import java.util.Set;
+import java.util.stream.Collectors;
+import java.util.stream.DoubleStream;
+import java.util.stream.IntStream;
+import java.util.stream.LongStream;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.teavm.junit.TeaVMTestRunner;
+import org.teavm.junit.WholeClassCompilation;
+
+@RunWith(TeaVMTestRunner.class)
+@WholeClassCompilation
+public class RandomTest {
+    @Test
+    public void testDoubles() {
+        Random random = new Random();
+        double[] doubles = IntStream.range(0, 1000).mapToDouble(i -> random.nextDouble()).toArray();
+        for (double d : doubles) {
+            assertTrue(d >= 0.0 && d < 1.0);
+        }
+        try {
+            random.nextDouble(-1.0);
+            fail();
+        } catch (IllegalArgumentException e) {
+            // normal
+        }
+        doubles = IntStream.range(0, 1000).mapToDouble(i -> random.nextDouble(20.0)).toArray();
+        for (double d : doubles) {
+            assertTrue(d >= 0.0 && d < 20.0);
+        }
+        try {
+            random.nextDouble(-1.0, -2.0);
+            fail();
+        } catch (IllegalArgumentException e) {
+            // normal
+        }
+        doubles = IntStream.range(0, 1000).mapToDouble(i -> random.nextDouble(-2.0, -1.0)).toArray();
+        for (double d : doubles) {
+            assertTrue(d >= -2.0 && d < 1.0);
+        }
+    }
+
+    @Test
+    public void testIntegers() {
+        Random random = new Random();
+        int[] ints = IntStream.range(0, 10000).map(i -> random.nextInt())
+                .toArray(); // 10 000 enough for almost 100% probability
+        int ones = IntStream.of(ints).reduce(0, (id, i) -> id | i);
+        Set<Integer> unique = Arrays.stream(ints).boxed().collect(Collectors.toSet());
+        assertEquals(-1, ones); // all ones present
+        assertTrue(unique.size() > 9900);
+        try {
+            random.nextInt(-5);
+            fail();
+        } catch (IllegalArgumentException e) {
+            // normal
+        }
+        ints = IntStream.range(0, 1000).map(i -> random.nextInt(512)).toArray();
+        for (int i : ints) {
+            assertTrue(i >= 0 && i < 512);
+        }
+        ints = IntStream.range(0, 1000).map(i -> random.nextInt(20)).toArray();
+        for (int i : ints) {
+            assertTrue(i >= 0 && i < 20);
+        }
+        try {
+            random.nextInt(-3, -5);
+            fail();
+        } catch (IllegalArgumentException e) {
+            // normal
+        }
+        ints = IntStream.range(0, 1000).map(i -> random.nextInt(Integer.MIN_VALUE / 3 * 2, Integer.MAX_VALUE / 3 * 2))
+                .toArray();
+        for (int i : ints) {
+            assertTrue(i >= Integer.MIN_VALUE / 3 * 2 && i < Integer.MAX_VALUE / 3 * 2);
+        }
+        Arrays.stream(ints).anyMatch(i -> i < Integer.MIN_VALUE / 2);
+        Arrays.stream(ints).anyMatch(i -> i > Integer.MAX_VALUE / 2);
+    }
+
+    @Test
+    public void testLongs() {
+        Random random = new Random();
+        long[] longs = IntStream.range(0, 10000).mapToLong(i -> random.nextLong())
+                .toArray(); // 10 000 enough for almost 100% probability
+        long ones = LongStream.of(longs).reduce(0L, (id, i) -> id | i);
+        Set<Long> unique = Arrays.stream(longs).boxed().collect(Collectors.toSet());
+        assertEquals(-1L, ones); // all ones present
+        assertTrue(unique.size() > 9900);
+        try {
+            random.nextLong(-5);
+            fail();
+        } catch (IllegalArgumentException e) {
+            // normal
+        }
+        longs = IntStream.range(0, 1000).mapToLong(i -> random.nextLong(512L)).toArray();
+        for (long l : longs) {
+            assertTrue(l >= 0L && l < 512L);
+        }
+        longs = IntStream.range(0, 1000).mapToLong(i -> random.nextLong(20L)).toArray();
+        for (long l : longs) {
+            assertTrue(l >= 0 && l < 20);
+        }
+        try {
+            random.nextLong(-3, -5);
+            fail();
+        } catch (IllegalArgumentException e) {
+            // normal
+        }
+        longs = IntStream.range(0, 1000).mapToLong(i -> random.nextLong(Long.MIN_VALUE / 3 * 2, Long.MAX_VALUE / 3 * 2))
+                .toArray();
+        for (long l : longs) {
+            assertTrue(l >= Long.MIN_VALUE / 3 * 2 && l < Long.MAX_VALUE / 3 * 2);
+        }
+        Arrays.stream(longs).anyMatch(l -> l < Long.MIN_VALUE / 2);
+        Arrays.stream(longs).anyMatch(l -> l > Long.MAX_VALUE / 2);
+    }
+
+    @Test
+    public void testNextBytes() {
+        Random rand = new Random();
+        rand.nextBytes(new byte[0]);
+        assertTrue(IntStream.range(0, 1000).anyMatch(i -> testNonZero(rand, 5)));
+        assertTrue(IntStream.range(0, 1000).anyMatch(i -> testNonZero(rand, 6)));
+        assertTrue(IntStream.range(0, 1000).anyMatch(i -> testNonZero(rand, 7)));
+        assertTrue(IntStream.range(0, 1000).anyMatch(i -> testNonZero(rand, 8)));
+        byte[] bytes = new byte[1000];
+        rand.nextBytes(bytes);
+        assertEquals(0xFF, IntStream.range(0, bytes.length).map(i -> 0xFF & bytes[i]).reduce(0, (id, i) -> id | i));
+    }
+
+    private boolean testNonZero(Random rand, int size) {
+        byte[] bytes = new byte[size];
+        rand.nextBytes(bytes);
+        for (byte b : bytes) {
+            if (b == 0) {
+                return false;
+            }
+        }
+        return true;
+    }
+
+    @Test
+    public void testGaussian() {
+        Random rand = new Random();
+        double[] doubles = IntStream.range(0, 10000).mapToDouble(i -> rand.nextGaussian(30, 10)).toArray();
+        assertTrue(DoubleStream.of(doubles).filter(d -> d < 0.0 || d > 60.0).count() < 100);
+    }
+}