diff --git a/.travis.yml b/.travis.yml
index bb0ec678..f7258a07 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -14,6 +14,7 @@ matrix:
       env: WITH_CS=true
     - php: 7 # PHPUnit 6.x
     - php: 7.1 # PHPUnit 7.x
+    - php: 7.2 # PHPUnit 7.x
     - php: hhvm
       env: SKIP_LINT_TEST_CASES=1
       sudo: required
diff --git a/docs/limits.rst b/docs/limits.rst
index a2a8bc41..79f4396a 100644
--- a/docs/limits.rst
+++ b/docs/limits.rst
@@ -6,10 +6,10 @@ Time and iterations
 
 By default Eris extracts a sample of 100 values for each ``forAll()`` call, and runs the ``then()`` callback over each of them.
 
-For tests which take very long to run, it is possible to either limit the number of elements in the sample, or to specify a time limit the test should not exceed. For this purpose, the ``limitTo()`` method accepts either:
+For tests which take very long to run, it is possible to limit the number of elements in the sample, or to specify a time limit the test should not exceed. For this purpose, the you can use the following annotations:
 
-* an integer requesting a fixed number of iterations;
-* a `DateInterval`_ object from the standard PHP library.
+* `@eris-repeat {number}` with an integer requesting a fixed number of iterations;
+* `@eris-duration {definition}` with a `DateInterval`_ compatible definition.
  
 .. literalinclude:: ../examples/LimitToTest.php
    :language: php
diff --git a/docs/listeners.rst b/docs/listeners.rst
index ee7a44b2..60372025 100644
--- a/docs/listeners.rst
+++ b/docs/listeners.rst
@@ -97,7 +97,7 @@ It is not advised to rely on this format for parsing, being it only oriented to
 Minimum Evaluations
 ---
 
-The ``minimumEvaluations($ratio)`` API method instantiates and wires in a Listener that checks that at least ``$ratio`` of the total number of inputs being generated is actually evaluated. This Listener is only needed in case of an aggressive use of ``when()``.
+The ``@eris-ratio {ratio}`` annotation instantiates and wires in a Listener that checks that at least ``ratio``% of the total number of inputs being generated is actually evaluated. This Listener is only needed in case of an aggressive use of ``when()``.
 
 Management of this Listener is provided through this method instead of explicitly adding a Listener object, as there is a default Listener instantiated with a threshold of 0.5 that has to be replaced in case a new minimum is chosen.
 
diff --git a/docs/shrinking.rst b/docs/shrinking.rst
index c2c9bfe0..219e7655 100644
--- a/docs/shrinking.rst
+++ b/docs/shrinking.rst
@@ -105,7 +105,7 @@ The shrinking for this test will not run for more than 2 seconds (although the t
 
     1) ShrinkingTimeLimitTest::testLengthPreservation
     RuntimeException: Eris has reached the time limit for shrinking (2s elapsed of 2s), here it is presenting the simplest failure case.
-    If you can afford to spend more time to find a simpler failing input, increase it with $this->shrinkingTimeLimit($seconds).
+    If you can afford to spend more time to find a simpler failing input, increase it with the annotation '@eris-shrink {seconds}'.
 
     /home/giorgio/code/eris/src/Eris/Shrinker/Random.php:71
     /home/giorgio/code/eris/src/Eris/Quantifier/ForAll.php:128
diff --git a/examples/CharacterTest.php b/examples/CharacterTest.php
index 7a66b1b9..7939fbae 100644
--- a/examples/CharacterTest.php
+++ b/examples/CharacterTest.php
@@ -27,10 +27,12 @@ public function testLengthOfPrintableAsciiCharacters()
             });
     }
 
+    /**
+     * @eris-ratio 10
+     */
     public function testMultiplePrintableCharacters()
     {
         $this
-            ->minimumEvaluationRatio(0.1)
             ->forAll(
                 Generator\char(['basic-latin']),
                 Generator\char(['basic-latin'])
diff --git a/examples/LimitToTest.php b/examples/LimitToTest.php
index 5689b8f8..9297ac30 100644
--- a/examples/LimitToTest.php
+++ b/examples/LimitToTest.php
@@ -6,10 +6,12 @@ class LimitToTest extends PHPUnit_Framework_TestCase
 {
     use TestTrait;
 
+    /**
+     * @eris-repeat 5
+     */
     public function testNumberOfIterationsCanBeConfigured()
     {
-        $this->limitTo(5)
-             ->forAll(
+        $this->forAll(
                 Generator\int()
             )
             ->then(function ($value) {
@@ -33,11 +35,13 @@ public function testTimeIntervalToRunForCanBeConfiguredButItNeedsToProduceAtLeas
     }
      */
 
+    /**
+     * @eris-ratio 0
+     * @eris-duration PT2S
+     */
     public function testTimeIntervalToRunForCanBeConfiguredAndAVeryLowNumberOfIterationsCanBeIgnored()
     {
-        $this->minimumEvaluationRatio(0.0)
-             ->limitTo(new DateInterval("PT2S"))
-             ->forAll(
+        $this->forAll(
                 Generator\int()
             )
             ->then(function ($value) {
diff --git a/examples/LogFileTest.php b/examples/LogFileTest.php
index 726e87af..fcca1490 100644
--- a/examples/LogFileTest.php
+++ b/examples/LogFileTest.php
@@ -13,7 +13,7 @@ public function testWritingIterationsOnALogFile()
             ->forAll(
                 Generator\int()
             )
-            ->hook(Listener\log('/tmp/eris-log-file-test.log'))
+            ->hook(Listener\log(sys_get_temp_dir().'/eris-log-file-test.log'))
             ->then(function ($number) {
                 $this->assertInternalType('integer', $number);
             });
@@ -25,7 +25,7 @@ public function testLogOfFailuresAndShrinking()
             ->forAll(
                 Generator\int()
             )
-            ->hook(Listener\log('/tmp/eris-log-file-shrinking.log'))
+            ->hook(Listener\log(sys_get_temp_dir().'/eris-log-file-shrinking.log'))
             ->then(function ($number) {
                 $this->assertLessThanOrEqual(42, $number);
             });
diff --git a/examples/MinimumEvaluationsTest.php b/examples/MinimumEvaluationsTest.php
index 7056f163..2eea3879 100644
--- a/examples/MinimumEvaluationsTest.php
+++ b/examples/MinimumEvaluationsTest.php
@@ -19,10 +19,12 @@ public function testFailsBecauseOfTheLowEvaluationRatio()
             });
     }
 
+    /**
+     * @eris-ratio 1
+     */
     public function testPassesBecauseOfTheArtificiallyLowMinimumEvaluationRatio()
     {
         $this
-            ->minimumEvaluationRatio(0.01)
             ->forAll(
                 Generator\choose(0, 100)
             )
diff --git a/examples/RandConfigurationTest.php b/examples/RandConfigurationTest.php
index 30887fa7..4dfb66a9 100644
--- a/examples/RandConfigurationTest.php
+++ b/examples/RandConfigurationTest.php
@@ -7,10 +7,12 @@ class RandConfigurationTest extends PHPUnit_Framework_TestCase
 {
     use TestTrait;
 
+    /**
+     * @eris-method rand
+     */
     public function testUsingTheDefaultRandFunction()
     {
         $this
-            ->withRand('rand')
             ->forAll(
                 Generator\int()
             )
@@ -18,10 +20,12 @@ public function testUsingTheDefaultRandFunction()
             ->then($this->isInteger());
     }
 
+    /**
+     * @eris-method mt_rand
+     */
     public function testUsingTheDefaultMtRandFunction()
     {
         $this
-            ->withRand('mt_rand')
             ->forAll(
                 Generator\int()
             )
diff --git a/examples/SequenceTest.php b/examples/SequenceTest.php
index 203330e6..ae4f72fa 100644
--- a/examples/SequenceTest.php
+++ b/examples/SequenceTest.php
@@ -1,6 +1,5 @@
 <?php
 use Eris\Generator;
-use Eris\Listener;
 
 class SequenceTest extends PHPUnit_Framework_TestCase
 {
diff --git a/examples/ShrinkingTimeLimitTest.php b/examples/ShrinkingTimeLimitTest.php
index 1079ba4f..f59e73a3 100644
--- a/examples/ShrinkingTimeLimitTest.php
+++ b/examples/ShrinkingTimeLimitTest.php
@@ -14,10 +14,12 @@ class ShrinkingTimeLimitTest extends PHPUnit_Framework_TestCase
 {
     use Eris\TestTrait;
 
+    /**
+     * @eris-shrink 2
+     */
     public function testLengthPreservation()
     {
         $this
-            ->shrinkingTimeLimit(2)
             ->forAll(
                 Generator\string(),
                 Generator\string()
diff --git a/examples/StringTest.php b/examples/StringTest.php
index 70777920..c2fafc43 100644
--- a/examples/StringTest.php
+++ b/examples/StringTest.php
@@ -36,7 +36,7 @@ public function testLengthPreservation()
                 Generator\string(),
                 Generator\string()
             )
-            ->hook(Listener\log('/tmp/eris-string-shrinking.log'))
+            ->hook(Listener\log(sys_get_temp_dir().'/eris-string-shrinking.log'))
             ->then(function ($first, $second) {
                 $result = string_concatenation($first, $second);
                 $this->assertEquals(
diff --git a/examples/SuchThatTest.php b/examples/SuchThatTest.php
index aa172047..0523626c 100644
--- a/examples/SuchThatTest.php
+++ b/examples/SuchThatTest.php
@@ -55,7 +55,7 @@ public function testSuchThatAcceptsPHPUnitConstraints()
                     )
                 )
             )
-            ->hook(Listener\log('/tmp/eris-such-that.log'))
+            ->hook(Listener\log(sys_get_temp_dir().'/eris-such-that.log'))
             ->then($this->allNumbersAreBiggerThan(42));
     }
 
diff --git a/src/Facade.php b/src/Facade.php
index 38708fe4..2d857ac4 100644
--- a/src/Facade.php
+++ b/src/Facade.php
@@ -10,4 +10,13 @@ public function __construct()
         $this->erisSetupBeforeClass();
         $this->erisSetup();
     }
+
+    /**
+     * sadly this facade has no option to retrieve annotations of testcases
+     * @return array
+     */
+    protected function getAnnotations()
+    {
+        return array();
+    }
 }
diff --git a/src/Generator.php b/src/Generator.php
index 0b776e0c..526cd288 100644
--- a/src/Generator.php
+++ b/src/Generator.php
@@ -10,10 +10,10 @@ interface Generator
 {
     /**
      * @param int The generation size
-     * @param callable  a rand() function
+     * @param Random\RandomRange
      * @return GeneratedValueSingle<T>
      */
-    public function __invoke($size, $rand);
+    public function __invoke($size, Random\RandomRange $rand);
 
     /**
      * The conditions for terminating are either:
diff --git a/src/Generator/AssociativeArrayGenerator.php b/src/Generator/AssociativeArrayGenerator.php
index 1189ef7c..68cc7178 100644
--- a/src/Generator/AssociativeArrayGenerator.php
+++ b/src/Generator/AssociativeArrayGenerator.php
@@ -22,7 +22,7 @@ public function __construct(array $generators)
         $this->tupleGenerator = new TupleGenerator(array_values($generators));
     }
 
-    public function __invoke($size, $rand)
+    public function __invoke($size, \Eris\Random\RandomRange $rand)
     {
         $tuple = $this->tupleGenerator->__invoke($size, $rand);
         return $this->mapToAssociativeArray($tuple);
diff --git a/src/Generator/BindGenerator.php b/src/Generator/BindGenerator.php
index 70d9bc82..50e01a9a 100644
--- a/src/Generator/BindGenerator.php
+++ b/src/Generator/BindGenerator.php
@@ -22,7 +22,7 @@ public function __construct($innerGenerator, $outerGeneratorFactory)
         $this->outerGeneratorFactory = $outerGeneratorFactory;
     }
 
-    public function __invoke($size, $rand)
+    public function __invoke($size, \Eris\Random\RandomRange $rand)
     {
         $innerGeneratorValue = $this->innerGenerator->__invoke($size, $rand);
         $outerGenerator = call_user_func($this->outerGeneratorFactory, $innerGeneratorValue->unbox());
diff --git a/src/Generator/BooleanGenerator.php b/src/Generator/BooleanGenerator.php
index 45e3827b..e196c79c 100644
--- a/src/Generator/BooleanGenerator.php
+++ b/src/Generator/BooleanGenerator.php
@@ -2,7 +2,6 @@
 namespace Eris\Generator;
 
 use Eris\Generator;
-use DomainException;
 
 function bool()
 {
@@ -11,10 +10,10 @@ function bool()
 
 class BooleanGenerator implements Generator
 {
-    public function __invoke($_size, $rand)
+    public function __invoke($_size, \Eris\Random\RandomRange $rand)
     {
         $booleanValues = [true, false];
-        $randomIndex = $rand(0, count($booleanValues) - 1);
+        $randomIndex = $rand->rand(0, count($booleanValues) - 1);
 
         return GeneratedValueSingle::fromJustValue($booleanValues[$randomIndex], 'boolean');
     }
diff --git a/src/Generator/CharacterGenerator.php b/src/Generator/CharacterGenerator.php
index f4e78916..43b7bd2b 100644
--- a/src/Generator/CharacterGenerator.php
+++ b/src/Generator/CharacterGenerator.php
@@ -49,14 +49,13 @@ public function __construct($lowerLimit, $upperLimit)
         $this->shrinkingProgression = ArithmeticProgression::discrete($this->lowerLimit);
     }
 
-    public function __invoke($_size, $rand)
+    public function __invoke($_size, \Eris\Random\RandomRange $rand)
     {
-        return GeneratedValueSingle::fromJustValue(chr($rand($this->lowerLimit, $this->upperLimit)), 'character');
+        return GeneratedValueSingle::fromJustValue(chr($rand->rand($this->lowerLimit, $this->upperLimit)), 'character');
     }
 
     public function shrink(GeneratedValueSingle $element)
     {
-        $codePoint = ord($element->unbox());
         $shrinkedValue = chr($this->shrinkingProgression->next(ord($element->unbox())));
         return GeneratedValueSingle::fromJustValue($shrinkedValue, 'character');
     }
diff --git a/src/Generator/ChooseGenerator.php b/src/Generator/ChooseGenerator.php
index e9a0aca9..8538aae6 100644
--- a/src/Generator/ChooseGenerator.php
+++ b/src/Generator/ChooseGenerator.php
@@ -3,7 +3,6 @@
 
 use Eris\Generator;
 use InvalidArgumentException;
-use DomainException;
 
 if (!defined('ERIS_PHP_INT_MIN')) {
     define('ERIS_PHP_INT_MIN', ~PHP_INT_MAX);
@@ -42,9 +41,9 @@ public function __construct($x, $y)
         );
     }
 
-    public function __invoke($_size, $rand)
+    public function __invoke($_size, \Eris\Random\RandomRange $rand)
     {
-        $value = $rand($this->lowerLimit, $this->upperLimit);
+        $value = $rand->rand($this->lowerLimit, $this->upperLimit);
 
         return GeneratedValueSingle::fromJustValue($value, 'choose');
     }
diff --git a/src/Generator/ConstantGenerator.php b/src/Generator/ConstantGenerator.php
index 9b373443..da4055e7 100644
--- a/src/Generator/ConstantGenerator.php
+++ b/src/Generator/ConstantGenerator.php
@@ -2,7 +2,6 @@
 namespace Eris\Generator;
 
 use Eris\Generator;
-use DomainException;
 
 /**
  * @param mixed $value  the only value to generate
@@ -27,7 +26,7 @@ public function __construct($value)
         $this->value = $value;
     }
 
-    public function __invoke($_size, $rand)
+    public function __invoke($_size, \Eris\Random\RandomRange $rand)
     {
         return GeneratedValueSingle::fromJustValue($this->value, 'constant');
     }
diff --git a/src/Generator/DateGenerator.php b/src/Generator/DateGenerator.php
index dc8194cb..a77e21fc 100644
--- a/src/Generator/DateGenerator.php
+++ b/src/Generator/DateGenerator.php
@@ -3,7 +3,6 @@
 
 use Eris\Generator;
 use DateTime;
-use DomainException;
 
 function date($lowerLimit = null, $upperLimit = null)
 {
@@ -42,9 +41,9 @@ public function __construct(DateTime $lowerLimit, DateTime $upperLimit)
         $this->intervalInSeconds = $upperLimit->getTimestamp() - $lowerLimit->getTimestamp();
     }
 
-    public function __invoke($_size, $rand)
+    public function __invoke($_size, \Eris\Random\RandomRange $rand)
     {
-        $generatedOffset = $rand(0, $this->intervalInSeconds);
+        $generatedOffset = $rand->rand(0, $this->intervalInSeconds);
         return GeneratedValueSingle::fromJustValue(
             $this->fromOffset($generatedOffset),
             'date'
diff --git a/src/Generator/ElementsGenerator.php b/src/Generator/ElementsGenerator.php
index 14c58756..9d3ddecf 100644
--- a/src/Generator/ElementsGenerator.php
+++ b/src/Generator/ElementsGenerator.php
@@ -29,9 +29,9 @@ private function __construct($domain)
         $this->domain = $domain;
     }
 
-    public function __invoke($_size, $rand)
+    public function __invoke($_size, \Eris\Random\RandomRange $rand)
     {
-        $index = $rand(0, count($this->domain) - 1);
+        $index = $rand->rand(0, count($this->domain) - 1);
         return GeneratedValueSingle::fromJustValue($this->domain[$index], 'elements');
     }
 
diff --git a/src/Generator/FloatGenerator.php b/src/Generator/FloatGenerator.php
index 1d366353..72d28871 100644
--- a/src/Generator/FloatGenerator.php
+++ b/src/Generator/FloatGenerator.php
@@ -2,7 +2,6 @@
 namespace Eris\Generator;
 
 use Eris\Generator;
-use DomainException;
 
 function float()
 {
@@ -15,13 +14,13 @@ public function __construct()
     {
     }
 
-    public function __invoke($size, $rand)
+    public function __invoke($size, \Eris\Random\RandomRange $rand)
     {
-        $denominator = $rand(1, $size) ?: 1;
+        $denominator = $rand->rand(1, $size) ?: 1;
 
-        $value = (float) $rand(0, $size) / (float) $denominator;
+        $value = (float) $rand->rand(0, $size) / (float) $denominator;
 
-        $signedValue = $rand(0, 1) === 0
+        $signedValue = $rand->rand(0, 1) === 0
             ? $value
             : $value * (-1);
         return GeneratedValueSingle::fromJustValue($signedValue, 'float');
diff --git a/src/Generator/FrequencyGenerator.php b/src/Generator/FrequencyGenerator.php
index 7a01931b..17c57de8 100644
--- a/src/Generator/FrequencyGenerator.php
+++ b/src/Generator/FrequencyGenerator.php
@@ -2,7 +2,6 @@
 namespace Eris\Generator;
 
 use Eris\Generator;
-use DomainException;
 use InvalidArgumentException;
 
 /**
@@ -16,7 +15,6 @@ function frequency(/*$frequencyAndGenerator, $frequencyAndGenerator, ...*/)
 class FrequencyGenerator implements Generator
 {
     private $generators;
-    private $frequencies;
 
     public function __construct(array $generatorsWithFrequency)
     {
@@ -43,7 +41,7 @@ function ($generators, $generatorWithFrequency) {
         );
     }
 
-    public function __invoke($size, $rand)
+    public function __invoke($size, \Eris\Random\RandomRange $rand)
     {
         list($index, $generator) = $this->pickFrom($this->generators, $rand);
         $originalValue = $generator->__invoke($size, $rand);
@@ -77,11 +75,11 @@ public function shrink(GeneratedValueSingle $element)
     /**
      * @return array  two elements: index and Generator object
      */
-    private function pickFrom($generators, $rand)
+    private function pickFrom($generators, \Eris\Random\RandomRange $rand)
     {
         $acc = 0;
         $frequencies = $this->frequenciesFrom($generators);
-        $random = $rand(1, array_sum($frequencies));
+        $random = $rand->rand(1, array_sum($frequencies));
         foreach ($generators as $index => $generator) {
             $acc += $generator['frequency'];
             if ($random <= $acc) {
diff --git a/src/Generator/GeneratedValueOptions.php b/src/Generator/GeneratedValueOptions.php
index be7a4478..da726495 100644
--- a/src/Generator/GeneratedValueOptions.php
+++ b/src/Generator/GeneratedValueOptions.php
@@ -1,148 +1,140 @@
-<?php
-namespace Eris\Generator;
-
-use ArrayIterator;
-use IteratorAggregate;
-use LogicException;
-
-/**
- * Parametric with respect to the type <T> of its value,
- * which should be the type parameter <T> of all the contained GeneratedValueSingle
- * instances.
- *
- * Mainly used in shrinking, to support multiple options as possibilities
- * for shrinking a GeneratedValueSingle.
- *
- * This class tends to delegate operations to its last() elements for
- * backwards compatibility. So it can be used in context where a single
- * value is expected. The last of the options is usually the more conservative
- * in shrinking, for example subtracting 1 for the IntegerGenerator.
- */
-class GeneratedValueOptions implements GeneratedValue
-{
-    private $generatedValues;
-    
-    public function __construct(array $generatedValues)
-    {
-        $this->generatedValues = $generatedValues;
-    }
-
-    public static function mostPessimisticChoice(GeneratedValue $value)
-    {
-        if ($value instanceof GeneratedValueOptions) {
-            return $value->last();
-        } else {
-            return $value;
-        }
-    }
-
-    public function first()
-    {
-        return $this->generatedValues[0];
-    }
-
-    public function last()
-    {
-        if (count($this->generatedValues) == 0) {
-            throw new LogicException("This GeneratedValueOptions is empty");
-        }
-        return $this->generatedValues[count($this->generatedValues) - 1];
-    }
-
-    public function map(callable $callable, $generatorName)
-    {
-        return new self(array_map(
-            function ($value) use ($callable, $generatorName) {
-                return $value->map($callable, $generatorName);
-            },
-            $this->generatedValues
-        ));
-    }
-    
-    public function derivedIn($generatorName)
-    {
-        throw new RuntimeException("GeneratedValueOptions::derivedIn() is needed, uncomment it");
-        /*
-         * Not sure this is needed.
-            return $this->map(
-                function ($value) { return $value; },
-                $generatorName
-            );
-         */
-    }
-
-    /**
-     * @return self
-     */
-    public function add(GeneratedValueSingle $value)
-    {
-        return new self(array_merge(
-            $this->generatedValues,
-            [$value]
-        ));
-    }
-
-    public function remove(GeneratedValueSingle $value)
-    {
-        $generatedValues = $this->generatedValues;
-        $index = array_search($value, $generatedValues);
-        if ($index !== false) {
-            unset($generatedValues[$index]);
-        }
-        return new self(array_values($generatedValues));
-    }
-
-    /**
-     * @override
-     */
-    public function unbox()
-    {
-        return $this->last()->unbox();
-    }
-
-    /**
-     * @override
-     */
-    public function input()
-    {
-        return $this->last()->input();
-    }
-
-    /**
-     * @override
-     */
-    public function __toString()
-    {
-        return var_export($this, true);
-    }
-
-    /**
-     * @override
-     * @return string
-     */
-    public function generatorName()
-    {
-        return $this->last()->generatorName();
-    }
-
-    public function getIterator()
-    {
-        return new ArrayIterator($this->generatedValues);
-    }
-
-    public function count()
-    {
-        return count($this->generatedValues);
-    }
-
-    public function cartesianProduct($generatedValueOptions, callable $merge)
-    {
-        $options = [];
-        foreach ($this as $firstPart) {
-            foreach ($generatedValueOptions as $secondPart) {
-                $options[] = $firstPart->merge($secondPart, $merge);
-            }
-        }
-        return new self($options);
-    }
-}
+<?php
+namespace Eris\Generator;
+
+use ArrayIterator;
+use LogicException;
+
+/**
+ * Parametric with respect to the type <T> of its value,
+ * which should be the type parameter <T> of all the contained GeneratedValueSingle
+ * instances.
+ *
+ * Mainly used in shrinking, to support multiple options as possibilities
+ * for shrinking a GeneratedValueSingle.
+ *
+ * This class tends to delegate operations to its last() elements for
+ * backwards compatibility. So it can be used in context where a single
+ * value is expected. The last of the options is usually the more conservative
+ * in shrinking, for example subtracting 1 for the IntegerGenerator.
+ */
+class GeneratedValueOptions implements GeneratedValue
+{
+    private $generatedValues;
+    
+    public function __construct(array $generatedValues)
+    {
+        $this->generatedValues = $generatedValues;
+    }
+
+    public static function mostPessimisticChoice(GeneratedValue $value)
+    {
+        if ($value instanceof GeneratedValueOptions) {
+            return $value->last();
+        } else {
+            return $value;
+        }
+    }
+
+    public function first()
+    {
+        return $this->generatedValues[0];
+    }
+
+    public function last()
+    {
+        if (count($this->generatedValues) == 0) {
+            throw new LogicException("This GeneratedValueOptions is empty");
+        }
+        return $this->generatedValues[count($this->generatedValues) - 1];
+    }
+
+    public function map(callable $callable, $generatorName)
+    {
+        return new self(array_map(
+            function ($value) use ($callable, $generatorName) {
+                return $value->map($callable, $generatorName);
+            },
+            $this->generatedValues
+        ));
+    }
+    
+    public function derivedIn($generatorName)
+    {
+        throw new RuntimeException("GeneratedValueOptions::derivedIn() is needed, uncomment it");
+    }
+
+    /**
+     * @return self
+     */
+    public function add(GeneratedValueSingle $value)
+    {
+        return new self(array_merge(
+            $this->generatedValues,
+            [$value]
+        ));
+    }
+
+    public function remove(GeneratedValueSingle $value)
+    {
+        $generatedValues = $this->generatedValues;
+        $index = array_search($value, $generatedValues);
+        if ($index !== false) {
+            unset($generatedValues[$index]);
+        }
+        return new self(array_values($generatedValues));
+    }
+
+    /**
+     * @override
+     */
+    public function unbox()
+    {
+        return $this->last()->unbox();
+    }
+
+    /**
+     * @override
+     */
+    public function input()
+    {
+        return $this->last()->input();
+    }
+
+    /**
+     * @override
+     */
+    public function __toString()
+    {
+        return var_export($this, true);
+    }
+
+    /**
+     * @override
+     * @return string
+     */
+    public function generatorName()
+    {
+        return $this->last()->generatorName();
+    }
+
+    public function getIterator()
+    {
+        return new ArrayIterator($this->generatedValues);
+    }
+
+    public function count()
+    {
+        return count($this->generatedValues);
+    }
+
+    public function cartesianProduct($generatedValueOptions, callable $merge)
+    {
+        $options = [];
+        foreach ($this as $firstPart) {
+            foreach ($generatedValueOptions as $secondPart) {
+                $options[] = $firstPart->merge($secondPart, $merge);
+            }
+        }
+        return new self($options);
+    }
+}
diff --git a/src/Generator/IntegerGenerator.php b/src/Generator/IntegerGenerator.php
index e0bc1b73..33c8da2e 100644
--- a/src/Generator/IntegerGenerator.php
+++ b/src/Generator/IntegerGenerator.php
@@ -2,7 +2,6 @@
 namespace Eris\Generator;
 
 use Eris\Generator;
-use DomainException;
 
 /**
  * Generates a positive or negative integer (with absolute value bounded by
@@ -61,12 +60,12 @@ public function __construct(callable $mapFn = null)
         }
     }
 
-    public function __invoke($size, $rand)
+    public function __invoke($size, \Eris\Random\RandomRange $rand)
     {
-        $value = $rand(0, $size);
+        $value = $rand->rand(0, $size);
         $mapFn = $this->mapFn;
 
-        $result = $rand(0, 1) === 0
+        $result = $rand->rand(0, 1) === 0
                           ? $mapFn($value)
                           : $mapFn($value * (-1));
         return GeneratedValueSingle::fromJustValue(
diff --git a/src/Generator/MapGenerator.php b/src/Generator/MapGenerator.php
index 70df70e9..4a5fc86f 100644
--- a/src/Generator/MapGenerator.php
+++ b/src/Generator/MapGenerator.php
@@ -20,7 +20,7 @@ public function __construct(callable $map, $generator)
         $this->generator = $generator;
     }
 
-    public function __invoke($_size, $rand)
+    public function __invoke($_size, \Eris\Random\RandomRange $rand)
     {
         $input = $this->generator->__invoke($_size, $rand);
         return $input->map(
diff --git a/src/Generator/NamesGenerator.php b/src/Generator/NamesGenerator.php
index 020121de..bb038afc 100644
--- a/src/Generator/NamesGenerator.php
+++ b/src/Generator/NamesGenerator.php
@@ -32,7 +32,7 @@ public function __construct(array $list)
         $this->list = $list;
     }
 
-    public function __invoke($size, $rand)
+    public function __invoke($size, \Eris\Random\RandomRange $rand)
     {
         $candidateNames = $this->filterDataSet(
             $this->lengthLessThanOrEqualTo($size)
@@ -40,7 +40,7 @@ public function __invoke($size, $rand)
         if (!$candidateNames) {
             return GeneratedValueSingle::fromJustValue('', 'names');
         }
-        $index = $rand(0, count($candidateNames) - 1);
+        $index = $rand->rand(0, count($candidateNames) - 1);
         return GeneratedValueSingle::fromJustValue($candidateNames[$index], 'names');
     }
 
diff --git a/src/Generator/OneOfGenerator.php b/src/Generator/OneOfGenerator.php
index b0351b4a..94e1bdf0 100644
--- a/src/Generator/OneOfGenerator.php
+++ b/src/Generator/OneOfGenerator.php
@@ -20,7 +20,7 @@ public function __construct($generators)
         $this->generator = new FrequencyGenerator($this->allWithSameFrequency($generators));
     }
 
-    public function __invoke($size, $rand)
+    public function __invoke($size, \Eris\Random\RandomRange $rand)
     {
         return $this->generator->__invoke($size, $rand);
     }
diff --git a/src/Generator/RegexGenerator.php b/src/Generator/RegexGenerator.php
index 4a59b5b0..de619240 100644
--- a/src/Generator/RegexGenerator.php
+++ b/src/Generator/RegexGenerator.php
@@ -33,10 +33,10 @@ public function __construct($expression)
         $this->expression = $expression;
     }
 
-    public function __invoke($_size, $rand)
+    public function __invoke($_size, \Eris\Random\RandomRange $rand)
     {
         $lexer = new Lexer($this->expression);
-        $gen   = new SimpleRandom($rand());
+        $gen   = new SimpleRandom($rand->rand());
         $result = null;
 
         $parser = new Parser($lexer, new Scope(), new Scope());
diff --git a/src/Generator/SequenceGenerator.php b/src/Generator/SequenceGenerator.php
index f0e0206b..74de4922 100644
--- a/src/Generator/SequenceGenerator.php
+++ b/src/Generator/SequenceGenerator.php
@@ -2,7 +2,6 @@
 namespace Eris\Generator;
 
 use Eris\Generator;
-use DomainException;
 
 function seq(Generator $singleElementGenerator)
 {
@@ -22,9 +21,9 @@ public function __construct(Generator $singleElementGenerator)
         $this->singleElementGenerator = $singleElementGenerator;
     }
 
-    public function __invoke($size, $rand)
+    public function __invoke($size, \Eris\Random\RandomRange $rand)
     {
-        $sequenceLength = $rand(0, $size);
+        $sequenceLength = $rand->rand(0, $size);
         return $this->vector($sequenceLength)->__invoke($size, $rand);
     }
 
diff --git a/src/Generator/SetGenerator.php b/src/Generator/SetGenerator.php
index 0120e2fc..b2dd3188 100644
--- a/src/Generator/SetGenerator.php
+++ b/src/Generator/SetGenerator.php
@@ -2,7 +2,6 @@
 namespace Eris\Generator;
 
 use Eris\Generator;
-use DomainException;
 
 /**
  * @param Generator $singleElementGenerator
@@ -22,7 +21,7 @@ public function __construct(Generator $singleElementGenerator)
         $this->singleElementGenerator = $singleElementGenerator;
     }
 
-    public function __invoke($size, $rand)
+    public function __invoke($size, \Eris\Random\RandomRange $rand)
     {
         $setSize = rand(0, $size);
         $set = [];
diff --git a/src/Generator/StringGenerator.php b/src/Generator/StringGenerator.php
index 92cfb7a4..2897f32d 100644
--- a/src/Generator/StringGenerator.php
+++ b/src/Generator/StringGenerator.php
@@ -2,7 +2,6 @@
 namespace Eris\Generator;
 
 use Eris\Generator;
-use DomainException;
 
 function string()
 {
@@ -11,13 +10,13 @@ function string()
 
 class StringGenerator implements Generator
 {
-    public function __invoke($size, $rand)
+    public function __invoke($size, \Eris\Random\RandomRange $rand)
     {
-        $length = $rand(0, $size);
+        $length = $rand->rand(0, $size);
 
         $built = '';
         for ($i = 0; $i < $length; $i++) {
-            $built .= chr($rand(33, 126));
+            $built .= chr($rand->rand(33, 126));
         }
         return GeneratedValueSingle::fromJustValue($built, 'string');
     }
diff --git a/src/Generator/SubsetGenerator.php b/src/Generator/SubsetGenerator.php
index a7aefdba..573ae055 100644
--- a/src/Generator/SubsetGenerator.php
+++ b/src/Generator/SubsetGenerator.php
@@ -24,11 +24,11 @@ public function __construct(array $universe)
         $this->universe = $universe;
     }
 
-    public function __invoke($size, $rand)
+    public function __invoke($size, \Eris\Random\RandomRange $rand)
     {
         $relativeSize = $size / ForAll::DEFAULT_MAX_SIZE;
         $maximumSubsetIndex = floor(pow(2, count($this->universe)) * $relativeSize);
-        $subsetIndex = $rand(0, $maximumSubsetIndex);
+        $subsetIndex = $rand->rand(0, $maximumSubsetIndex);
         $binaryDescription = str_pad(decbin($subsetIndex), count($this->universe), "0", STR_PAD_LEFT);
         $subset = [];
         for ($i = 0; $i < strlen($binaryDescription); $i++) {
diff --git a/src/Generator/SuchThatGenerator.php b/src/Generator/SuchThatGenerator.php
index 2353bb98..7e677242 100644
--- a/src/Generator/SuchThatGenerator.php
+++ b/src/Generator/SuchThatGenerator.php
@@ -43,7 +43,7 @@ public function __construct($filter, $generator, $maximumAttempts = 100)
         $this->maximumAttempts = $maximumAttempts;
     }
 
-    public function __invoke($size, $rand)
+    public function __invoke($size, \Eris\Random\RandomRange $rand)
     {
         $value = $this->generator->__invoke($size, $rand);
         $attempts = 0;
diff --git a/src/Generator/TupleGenerator.php b/src/Generator/TupleGenerator.php
index 7d4763d5..c3788e22 100644
--- a/src/Generator/TupleGenerator.php
+++ b/src/Generator/TupleGenerator.php
@@ -2,7 +2,6 @@
 namespace Eris\Generator;
 
 use Eris\Generator;
-use DomainException;
 
 /**
  * One Generator for each member of the Tuple:
@@ -25,7 +24,6 @@ function tuple()
 class TupleGenerator implements Generator
 {
     private $generators;
-    private $size;
     private $numberOfGenerators;
 
     public function __construct(array $generators)
@@ -34,7 +32,7 @@ public function __construct(array $generators)
         $this->numberOfGenerators = count($generators);
     }
 
-    public function __invoke($size, $rand)
+    public function __invoke($size, \Eris\Random\RandomRange $rand)
     {
         $input = array_map(
             function ($generator) use ($size, $rand) {
diff --git a/src/Generator/VectorGenerator.php b/src/Generator/VectorGenerator.php
index c9678c0f..a05d5e34 100644
--- a/src/Generator/VectorGenerator.php
+++ b/src/Generator/VectorGenerator.php
@@ -2,7 +2,6 @@
 namespace Eris\Generator;
 
 use Eris\Generator;
-use DomainException;
 
 function vector($size, Generator $elementsGenerator)
 {
@@ -24,7 +23,7 @@ public function __construct($size, Generator $generator)
         $this->elementsGeneratorClass = get_class($generator);
     }
 
-    public function __invoke($size, $rand)
+    public function __invoke($size, \Eris\Random\RandomRange $rand)
     {
         return $this->generator->__invoke($size, $rand);
     }
diff --git a/src/Quantifier/ForAll.php b/src/Quantifier/ForAll.php
index d12bc2e0..2911a702 100644
--- a/src/Quantifier/ForAll.php
+++ b/src/Quantifier/ForAll.php
@@ -29,10 +29,14 @@ class ForAll
     private $terminationConditions = [];
     private $listeners = [];
     private $shrinkerFactoryMethod;
+
+    /**
+     * @var RandomRange
+     */
     private $rand;
     private $shrinkingEnabled = true;
 
-    public function __construct(array $generators, $iterations, $shrinkerFactory, $shrinkerFactoryMethod, $rand)
+    public function __construct(array $generators, $iterations, $shrinkerFactory, $shrinkerFactoryMethod, \Eris\Random\RandomRange $rand)
     {
         $this->generators = $this->generatorsFrom($generators);
         $this->iterations = $iterations;
@@ -167,8 +171,7 @@ public function __invoke(callable $assertion)
             }
         } catch (Exception $e) {
             $redTestException = $e;
-            $wrap = (bool) getenv('ERIS_ORIGINAL_INPUT');
-            if ($wrap) {
+            if ((bool) getenv('ERIS_ORIGINAL_INPUT')) {
                 $message = "Original input: " . var_export($values, true) . PHP_EOL
                     . "Possibly shrinked input follows." . PHP_EOL;
                 throw new RuntimeException($message, -1, $e);
diff --git a/src/Random/MersenneTwister.php b/src/Random/MersenneTwister.php
index cdb91328..2a478d84 100644
--- a/src/Random/MersenneTwister.php
+++ b/src/Random/MersenneTwister.php
@@ -43,27 +43,27 @@ public function seed($seed)
             $this->mt[$i] = ($this->f * (
                 $this->mt[$i - 1] ^ (($this->mt[$i - 1] >> ($this->w - 2)) & 0b11)
             ) + $i) & $this->wMask;
-            assert('$this->mt[$i] <= $this->wMask');
+            assert($this->mt[$i] <= $this->wMask);
         }
-        assert('count($this->mt) === 624');
+        assert(count($this->mt) === 624);
         return $this;
     }
 
     public function extractNumber()
     {
-        assert('$this->index <= $this->n');
+        assert($this->index <= $this->n);
         if ($this->index >= $this->n) {
             $this->twist();
         }
         $y = $this->mt[$this->index];
         $y = $y ^ (($y >> $this->u) & $this->d);
-        assert('$y <= 0xffffffff');
+        assert($y <= 0xffffffff);
         $y = $y ^ (($y << $this->s) & $this->b);
-        assert('$y <= 0xffffffff');
+        assert($y <= 0xffffffff);
         $y = $y ^ (($y << $this->t) & $this->c);
-        assert('$y <= 0xffffffff');
+        assert($y <= 0xffffffff);
         $y = $y ^ ($y >> $this->l);
-        assert('$y <= 0xffffffff');
+        assert($y <= 0xffffffff);
         $this->index = $this->index + 1;
         return $y & $this->wMask;
     }
@@ -78,9 +78,9 @@ private function twist()
         for ($i = 0; $i <= $this->n - 1; $i++) {
             $x = ($this->mt[$i] & $this->upperMask)
                + (($this->mt[($i+1) % $this->n]) & $this->lowerMask);
-            assert('$x <= 0xffffffff');
+            assert($x <= 0xffffffff);
             $xA = $x >> 1;
-            assert('$xA <= 0x7fffffff');
+            assert($xA <= 0x7fffffff);
             if (($x % 2) != 0) {
                 $xA = $xA ^ $this->a;
             }
diff --git a/src/Random/MtRandSource.php b/src/Random/MtRandSource.php
new file mode 100644
index 00000000..ad50c44c
--- /dev/null
+++ b/src/Random/MtRandSource.php
@@ -0,0 +1,33 @@
+<?php
+
+namespace Eris\Random;
+
+class MtRandSource implements Source
+{
+    /**
+     * Returns a random number between 0 and @see max().
+     * @return integer
+     */
+    public function extractNumber()
+    {
+        return mt_rand(0, $this->max());
+    }
+
+    /**
+     * @return integer
+     */
+    public function max()
+    {
+        return mt_getrandmax();
+    }
+
+    /**
+     * @param integer $seed
+     * @return self
+     */
+    public function seed($seed)
+    {
+        mt_srand($seed);
+        return $this;
+    }
+}
diff --git a/src/Random/RandSource.php b/src/Random/RandSource.php
new file mode 100644
index 00000000..16e5ac84
--- /dev/null
+++ b/src/Random/RandSource.php
@@ -0,0 +1,33 @@
+<?php
+
+namespace Eris\Random;
+
+class RandSource implements Source
+{
+    /**
+     * Returns a random number between 0 and @see max().
+     * @return integer
+     */
+    public function extractNumber()
+    {
+        return rand(0, $this->max());
+    }
+
+    /**
+     * @return integer
+     */
+    public function max()
+    {
+        return getrandmax();
+    }
+
+    /**
+     * @param integer $seed
+     * @return self
+     */
+    public function seed($seed)
+    {
+        srand($seed);
+        return $this;
+    }
+}
diff --git a/src/Random/RandomRange.php b/src/Random/RandomRange.php
index 2658d798..e9b2880d 100644
--- a/src/Random/RandomRange.php
+++ b/src/Random/RandomRange.php
@@ -43,6 +43,9 @@ public function rand($lower = null, $upper = null)
             return $this->source->extractNumber();
         }
 
+        if ($lower > $upper) {
+            list($lower, $upper) = [$upper, $lower];
+        }
         $delta = $upper - $lower;
         $divisor = ($this->source->max()) / ($delta + 1);
 
diff --git a/src/Shrinker/Multiple.php b/src/Shrinker/Multiple.php
index b495f31a..92d70952 100644
--- a/src/Shrinker/Multiple.php
+++ b/src/Shrinker/Multiple.php
@@ -71,7 +71,7 @@ public function from(GeneratedValueSingle $elements, $exception)
             if ($this->timeLimit->hasBeenReached()) {
                 throw new \RuntimeException(
                     "Eris has reached the time limit for shrinking ($this->timeLimit), here it is presenting the simplest failure case." . PHP_EOL
-                    . "If you can afford to spend more time to find a simpler failing input, increase it with \$this->shrinkingTimeLimit(\$seconds).",
+                    . "If you can afford to spend more time to find a simpler failing input, increase it with the annotation \'@eris-shrink {seconds}\'.",
                     -1,
                     $exception
                 );
diff --git a/src/TestTrait.php b/src/TestTrait.php
index 2b292ea9..32431ef3 100644
--- a/src/TestTrait.php
+++ b/src/TestTrait.php
@@ -1,9 +1,15 @@
 <?php
 namespace Eris;
 
-use OutOfBoundsException;
+use BadMethodCallException;
 use DateInterval;
-use InvalidArgumentException;
+use Eris\Listener\MinimumEvaluations;
+use Eris\Quantifier\ForAll;
+use Eris\Quantifier\TimeBasedTerminationCondition;
+use Eris\Random\MtRandSource;
+use Eris\Random\RandomRange;
+use Eris\Random\RandSource;
+use Eris\Shrinker\ShrinkerFactory;
 
 trait TestTrait
 {
@@ -13,8 +19,10 @@ trait TestTrait
     private $iterations = 100;
     private $listeners = [];
     private $terminationConditions = [];
-    private $randFunction = 'rand';
-    private $seedFunction = 'srand';
+    /**
+     * @var RandomRange
+     */
+    private $randFunction;
     private $shrinkerFactoryMethod = 'multiple';
     protected $seed;
     protected $shrinkingTimeLimit;
@@ -36,93 +44,73 @@ public static function erisSetupBeforeClass()
      */
     public function erisSetup()
     {
-        $this->seedingRandomNumberGeneration();
-        $this->minimumEvaluationRatio(0.5);
+        $this->seed = intval(getenv('ERIS_SEED') ?: (microtime(true)*1000000));
+        if ($this->seed < 0) {
+            $this->seed *= -1;
+        }
+        $this->listeners = array_filter(
+            $this->listeners,
+            function ($listener) {
+                return !($listener instanceof MinimumEvaluations);
+            }
+        );
+        $tags = $this->getAnnotations();//from TestCase of PHPunit
+        $this->withRand($this->getAnnotationValue($tags, 'eris-method', 'rand', 'strval'));
+        $this->iterations = $this->getAnnotationValue($tags, 'eris-repeat', 100, 'intval');
+        $this->shrinkingTimeLimit = $this->getAnnotationValue($tags, 'eris-shrink', null, 'intval');
+        $this->listeners[] = MinimumEvaluations::ratio($this->getAnnotationValue($tags, 'eris-ratio', 50, 'floatval')/100);
+        $duration = $this->getAnnotationValue($tags, 'eris-duration', false, 'strval');
+        if ($duration) {
+            $terminationCondition = new TimeBasedTerminationCondition('time', new DateInterval($duration));
+            $this->listeners[] = $terminationCondition;
+            $this->terminationConditions[] = $terminationCondition;
+        }
     }
 
     /**
-     * @after
+     * @param array $annotations
+     * @param string $key
+     * @param mixed $default
+     * @return mixed
      */
-    public function erisTeardown()
+    private function getAnnotationValue(array $annotations, $key, $default, $cast)
     {
-        $this->dumpSeedForReproducing();
-    }
-
-    private function seedingRandomNumberGeneration()
-    {
-        if ($seed = getenv('ERIS_SEED')) {
-            $this->seed = $seed;
-        } else {
-            $this->seed = (int) (microtime(true)*1000000);
-        }
+        $annotation = $this->getAnnotation($annotations, $key);
+        return isset($annotation[0])?$cast($annotation[0]):$default;
     }
 
     /**
-     * Maybe: we could add --filter options to the command here,
-     * since now the original command is printed.
+     * @param array $annotations
+     * @param string $key
+     * @return array
      */
-    private function dumpSeedForReproducing()
+    private function getAnnotation(array $annotations, $key)
     {
-        if ($this->hasFailed()) {
-            global $argv;
-            $command = PHPUnitCommand::fromSeedAndName($this->seed, $this->toString());
-            echo PHP_EOL;
-            echo "Reproduce with:", PHP_EOL;
-            echo $command, PHP_EOL;
+        if (isset($annotations['method'][$key])) {
+            return $annotations['method'][$key];
         }
+        return isset($annotations['class'][$key])?$annotations['class'][$key]:[];
     }
 
     /**
-     * @param float  from 0.0 to 1.0
-     * @return self
+     * @after
      */
-    protected function minimumEvaluationRatio($ratio)
-    {
-        $this->filterOutListenersOfClass('Eris\\Listener\\MinimumEvaluations');
-        $this->listeners[] = Listener\MinimumEvaluations::ratio($ratio);
-        return $this;
-    }
-
-    private function filterOutListenersOfClass($className)
+    public function erisTeardown()
     {
-        $this->listeners = array_filter(
-            $this->listeners,
-            function ($listener) use ($className) {
-                return !($listener instanceof $className);
-            }
-        );
+        $this->dumpSeedForReproducing();
     }
 
     /**
-     * @param integer|DateInterval
-     * @return self
+     * Maybe: we could add --filter options to the command here,
+     * since now the original command is printed.
      */
-    protected function limitTo($limit)
+    private function dumpSeedForReproducing()
     {
-        if ($limit instanceof DateInterval) {
-            $interval = $limit;
-            $terminationCondition = new Quantifier\TimeBasedTerminationCondition('time', $interval);
-            $this->listeners[] = $terminationCondition;
-            $this->terminationConditions[] = $terminationCondition;
-        } elseif (is_integer($limit)) {
-            $this->iterations = $limit;
-        } else {
-            throw new InvalidArgumentException("The limit " . var_export($limit, true) . " is not valid. Please pass an integer or DateInterval.");
+        if (!$this->hasFailed()) {
+            return;
         }
-        return $this;
-    }
-
-    /**
-     * The maximum time to spend trying to shrink the input after a failed test.
-     * The default is no limit.
-     *
-     * @param integer  in seconds
-     * @return self
-     */
-    protected function shrinkingTimeLimit($shrinkingTimeLimit)
-    {
-        $this->shrinkingTimeLimit = $shrinkingTimeLimit;
-        return $this;
+        $command = PHPUnitCommand::fromSeedAndName($this->seed, $this->toString());
+        echo PHP_EOL."Reproduce with:".PHP_EOL.$command.PHP_EOL;
     }
 
     /**
@@ -130,44 +118,33 @@ protected function shrinkingTimeLimit($shrinkingTimeLimit)
      */
     protected function withRand($randFunction)
     {
-        // TODO: invert and wrap rand, srand into objects?
-        if ($randFunction instanceof \Eris\Random\RandomRange) {
-            $this->randFunction = function ($lower = null, $upper = null) use ($randFunction) {
-                return $randFunction->rand($lower, $upper);
-            };
-            $this->seedFunction = function ($seed) use ($randFunction) {
-                return $randFunction->seed($seed);
-            };
+        if ($randFunction === 'mt_rand') {
+            $this->randFunction = new RandomRange(new MtRandSource());
+            return $this;
         }
-        if (is_callable($randFunction)) {
-            switch ($randFunction) {
-                case 'rand':
-                    $seedFunction = 'srand';
-                    break;
-                case 'mt_rand':
-                    $seedFunction = 'mt_srand';
-                    break;
-                default:
-                    throw new BadMethodCallException("When specifying random generators different from the standard ones, you must also pass a \$seedFunction callable that will be called to seed it.");
-            }
+        if ($randFunction === 'rand') {
+            $this->randFunction = new RandomRange(new RandSource());
+            return $this;
+        }
+        if ($randFunction instanceof RandomRange) {
             $this->randFunction = $randFunction;
-            $this->seedFunction = $seedFunction;
+            return $this;
         }
-        return $this;
+        throw new BadMethodCallException("When specifying random generators different from the standard ones, you must also pass a \$seedFunction callable that will be called to seed it.");
     }
 
     /**
      * forAll($generator1, $generator2, ...)
-     * @return Quantifier\ForAll
+     * @return ForAll
      */
     public function forAll()
     {
-        call_user_func($this->seedFunction, $this->seed);
+        $this->randFunction->seed($this->seed);
         $generators = func_get_args();
-        $quantifier = new Quantifier\ForAll(
+        $quantifier = new ForAll(
             $generators,
             $this->iterations,
-            new Shrinker\ShrinkerFactory([
+            new ShrinkerFactory([
                 'timeLimit' => $this->shrinkingTimeLimit,
             ]),
             $this->shrinkerFactoryMethod,
diff --git a/test/ExampleEnd2EndTest.php b/test/ExampleEnd2EndTest.php
index 593613c0..089bc8a7 100644
--- a/test/ExampleEnd2EndTest.php
+++ b/test/ExampleEnd2EndTest.php
@@ -274,13 +274,15 @@ private function runExample($testFile)
     {
         $this->testFile = $testFile;
         $examplesDir = realpath(__DIR__ . '/../examples');
-        $samplesTestCase = $examplesDir . '/' . $testFile;
+        $samplesTestCase = $examplesDir . DIRECTORY_SEPARATOR . $testFile;
         $logFile = tempnam(sys_get_temp_dir(), 'phpunit_log_');
         $environmentVariables = [];
         foreach ($this->environment as $name => $value) {
-            $environmentVariables[] .= "$name=$value";
+            $var = "$name=$value";
+            $environmentVariables[] = DIRECTORY_SEPARATOR==='\\' ? "set $var && " : $var;
         }
-        $phpunitCommand = implode(" ", $environmentVariables) . " vendor/bin/phpunit --log-junit $logFile $samplesTestCase";
+        $bin = "vendor".DIRECTORY_SEPARATOR."bin".DIRECTORY_SEPARATOR."phpunit";
+        $phpunitCommand = implode(" ", $environmentVariables) . " $bin --log-junit $logFile $samplesTestCase";
         exec($phpunitCommand, $output);
         $contentsOfXmlLog = file_get_contents($logFile);
         if (!$contentsOfXmlLog) {
diff --git a/test/Generator/AssociativeArrayGeneratorTest.php b/test/Generator/AssociativeArrayGeneratorTest.php
index a1dc9002..3471e0c1 100644
--- a/test/Generator/AssociativeArrayGeneratorTest.php
+++ b/test/Generator/AssociativeArrayGeneratorTest.php
@@ -9,7 +9,7 @@ protected function setUp()
         $this->cipherGenerator = ElementsGenerator::fromArray([0, 1, 2]);
         $this->smallIntegerGenerator = new ChooseGenerator(0, 100);
         $this->size = 10;
-        $this->rand = 'rand';
+        $this->rand = new \Eris\Random\RandomRange(new \Eris\Random\RandSource());
     }
 
     public function testConstructWithAnAssociativeArrayOfGenerators()
diff --git a/test/Generator/BindGeneratorTest.php b/test/Generator/BindGeneratorTest.php
index fc1f7312..fac1f188 100644
--- a/test/Generator/BindGeneratorTest.php
+++ b/test/Generator/BindGeneratorTest.php
@@ -6,7 +6,7 @@ class BindGeneratorTest extends \PHPUnit_Framework_TestCase
     protected function setUp()
     {
         $this->size = 10;
-        $this->rand = 'rand';
+        $this->rand = new \Eris\Random\RandomRange(new \Eris\Random\RandSource());
     }
     
     public function testGeneratesAGeneratedValueObject()
diff --git a/test/Generator/BooleanGeneratorTest.php b/test/Generator/BooleanGeneratorTest.php
index b6e40a05..ba103e4b 100644
--- a/test/Generator/BooleanGeneratorTest.php
+++ b/test/Generator/BooleanGeneratorTest.php
@@ -5,7 +5,7 @@ class BooleanGeneratorTest extends \PHPUnit_Framework_TestCase
 {
     public function setUp()
     {
-        $this->rand = 'rand';
+        $this->rand = new \Eris\Random\RandomRange(new \Eris\Random\RandSource());
     }
     
     public function testRandomlyPicksTrueOrFalse()
diff --git a/test/Generator/CharacterGeneratorTest.php b/test/Generator/CharacterGeneratorTest.php
index 9d511287..d85c8d25 100644
--- a/test/Generator/CharacterGeneratorTest.php
+++ b/test/Generator/CharacterGeneratorTest.php
@@ -6,7 +6,7 @@ class CharacterGeneratorTest extends \PHPUnit_Framework_TestCase
     protected function setUp()
     {
         $this->size = 0;
-        $this->rand = 'rand';
+        $this->rand = new \Eris\Random\RandomRange(new \Eris\Random\RandSource());
     }
 
     public function testBasicAsciiCharacterGenerators()
diff --git a/test/Generator/ChooseGeneratorTest.php b/test/Generator/ChooseGeneratorTest.php
index deae0b3c..def11728 100644
--- a/test/Generator/ChooseGeneratorTest.php
+++ b/test/Generator/ChooseGeneratorTest.php
@@ -6,7 +6,7 @@ class ChooseGeneratorTest extends \PHPUnit_Framework_TestCase
     protected function setUp()
     {
         $this->size = 0; // ignored by this kind of generator
-        $this->rand = 'rand';
+        $this->rand = new \Eris\Random\RandomRange(new \Eris\Random\RandSource());
     }
 
     public function testPicksRandomlyAnIntegerAmongBoundaries()
diff --git a/test/Generator/ConstantGeneratorTest.php b/test/Generator/ConstantGeneratorTest.php
index afb5df17..ed4641ff 100644
--- a/test/Generator/ConstantGeneratorTest.php
+++ b/test/Generator/ConstantGeneratorTest.php
@@ -6,7 +6,7 @@ class ConstantGeneratorTest extends \PHPUnit_Framework_TestCase
     protected function setUp()
     {
         $this->size = 0;
-        $this->rand = 'rand';
+        $this->rand = new \Eris\Random\RandomRange(new \Eris\Random\RandSource());
     }
 
     public function testPicksAlwaysTheValue()
diff --git a/test/Generator/DateGeneratorTest.php b/test/Generator/DateGeneratorTest.php
index 30eebcbe..4ea26e6f 100644
--- a/test/Generator/DateGeneratorTest.php
+++ b/test/Generator/DateGeneratorTest.php
@@ -8,7 +8,7 @@ class DateGeneratorTest extends \PHPUnit_Framework_TestCase
     protected function setUp()
     {
         $this->size = 10;
-        $this->rand = 'rand';
+        $this->rand = new \Eris\Random\RandomRange(new \Eris\Random\RandSource());
     }
 
     public function testGenerateDateTimeObjectsInTheGivenInterval()
diff --git a/test/Generator/ElementsGeneratorTest.php b/test/Generator/ElementsGeneratorTest.php
index 47f98f19..829e3d79 100644
--- a/test/Generator/ElementsGeneratorTest.php
+++ b/test/Generator/ElementsGeneratorTest.php
@@ -6,7 +6,7 @@ class ElementsGeneratorTest extends \PHPUnit_Framework_TestCase
     protected function setUp()
     {
         $this->size = 10;
-        $this->rand = 'rand';
+        $this->rand = new \Eris\Random\RandomRange(new \Eris\Random\RandSource());
     }
 
     public function testGeneratesOnlyArgumentsInsideTheGivenArray()
diff --git a/test/Generator/FloatGeneratorTest.php b/test/Generator/FloatGeneratorTest.php
index b0c371a3..c214b799 100644
--- a/test/Generator/FloatGeneratorTest.php
+++ b/test/Generator/FloatGeneratorTest.php
@@ -6,7 +6,7 @@ class FloatGeneratorTest extends \PHPUnit_Framework_TestCase
     protected function setUp()
     {
         $this->size = 300;
-        $this->rand = 'rand';
+        $this->rand = new \Eris\Random\RandomRange(new \Eris\Random\RandSource());
     }
 
     public function testPicksUniformelyPositiveAndNegativeFloatNumbers()
diff --git a/test/Generator/FrequencyGeneratorTest.php b/test/Generator/FrequencyGeneratorTest.php
index f6f48af3..97269082 100644
--- a/test/Generator/FrequencyGeneratorTest.php
+++ b/test/Generator/FrequencyGeneratorTest.php
@@ -6,7 +6,7 @@ class FrequencyGeneratorTest extends \PHPUnit_Framework_TestCase
     protected function setUp()
     {
         $this->size = 10;
-        $this->rand = 'rand';
+        $this->rand = new \Eris\Random\RandomRange(new \Eris\Random\RandSource());
     }
 
     public function testEqualProbability()
diff --git a/test/Generator/IntegerGeneratorTest.php b/test/Generator/IntegerGeneratorTest.php
index 09f8abc4..88a17c5b 100644
--- a/test/Generator/IntegerGeneratorTest.php
+++ b/test/Generator/IntegerGeneratorTest.php
@@ -6,7 +6,7 @@ class IntegerGeneratorTest extends \PHPUnit_Framework_TestCase
     protected function setUp()
     {
         $this->size = 10;
-        $this->rand = 'rand';
+        $this->rand = new \Eris\Random\RandomRange(new \Eris\Random\RandSource());
     }
 
     public function testPicksRandomlyAnInteger()
diff --git a/test/Generator/MapGeneratorTest.php b/test/Generator/MapGeneratorTest.php
index 79885e0c..fed8df73 100644
--- a/test/Generator/MapGeneratorTest.php
+++ b/test/Generator/MapGeneratorTest.php
@@ -6,7 +6,7 @@ class MapGeneratorTest extends \PHPUnit_Framework_TestCase
     protected function setUp()
     {
         $this->size = 10;
-        $this->rand = 'rand';
+        $this->rand = new \Eris\Random\RandomRange(new \Eris\Random\RandSource());
     }
     
     public function testGeneratesAGeneratedValueObject()
diff --git a/test/Generator/NamesGeneratorTest.php b/test/Generator/NamesGeneratorTest.php
index b024c699..55fce511 100644
--- a/test/Generator/NamesGeneratorTest.php
+++ b/test/Generator/NamesGeneratorTest.php
@@ -5,7 +5,7 @@ class NamesGeneratorTest extends \PHPUnit_Framework_TestCase
 {
     public function setUp()
     {
-        $this->rand = 'rand';
+        $this->rand = new \Eris\Random\RandomRange(new \Eris\Random\RandSource());
     }
     
     public function testItRespectsTheGenerationSize()
diff --git a/test/Generator/OneOfGeneratorTest.php b/test/Generator/OneOfGeneratorTest.php
index cab4edf3..9dccb485 100644
--- a/test/Generator/OneOfGeneratorTest.php
+++ b/test/Generator/OneOfGeneratorTest.php
@@ -7,7 +7,7 @@ protected function setUp()
     {
         $this->singleElementGenerator = new ChooseGenerator(0, 100);
         $this->size = 10;
-        $this->rand = 'rand';
+        $this->rand = new \Eris\Random\RandomRange(new \Eris\Random\RandSource());
     }
 
     public function testConstructWithAnArrayOfGenerators()
diff --git a/test/Generator/RegexGeneratorTest.php b/test/Generator/RegexGeneratorTest.php
index 3eb1fee0..b184c1c4 100644
--- a/test/Generator/RegexGeneratorTest.php
+++ b/test/Generator/RegexGeneratorTest.php
@@ -18,7 +18,7 @@ public static function supportedRegexes()
     protected function setUp()
     {
         $this->size = 10;
-        $this->rand = 'rand';
+        $this->rand = new \Eris\Random\RandomRange(new \Eris\Random\RandSource());
     }
 
     /**
diff --git a/test/Generator/SequenceGeneratorTest.php b/test/Generator/SequenceGeneratorTest.php
index 678ed235..b3188c14 100644
--- a/test/Generator/SequenceGeneratorTest.php
+++ b/test/Generator/SequenceGeneratorTest.php
@@ -7,7 +7,7 @@ protected function setUp()
     {
         $this->size = 100;
         $this->singleElementGenerator = new ChooseGenerator(10, 100);
-        $this->rand = 'rand';
+        $this->rand = new \Eris\Random\RandomRange(new \Eris\Random\RandSource());
     }
 
     public function testRespectsGenerationSize()
diff --git a/test/Generator/SetGeneratorTest.php b/test/Generator/SetGeneratorTest.php
index 859f325e..96b297ae 100644
--- a/test/Generator/SetGeneratorTest.php
+++ b/test/Generator/SetGeneratorTest.php
@@ -7,7 +7,7 @@ protected function setUp()
     {
         $this->size = 100;
         $this->singleElementGenerator = new ChooseGenerator(10, 100);
-        $this->rand = 'rand';
+        $this->rand = new \Eris\Random\RandomRange(new \Eris\Random\RandSource());
     }
 
     public function testRespectsGenerationSize()
diff --git a/test/Generator/StringGeneratorTest.php b/test/Generator/StringGeneratorTest.php
index 47acb39b..51689d0a 100644
--- a/test/Generator/StringGeneratorTest.php
+++ b/test/Generator/StringGeneratorTest.php
@@ -5,7 +5,7 @@ class StringGeneratorTest extends \PHPUnit_Framework_TestCase
 {
     public function setUp()
     {
-        $this->rand = 'rand';
+        $this->rand = new \Eris\Random\RandomRange(new \Eris\Random\RandSource());
     }
     
     public function testRandomlyPicksLengthAndCharacters()
diff --git a/test/Generator/SubsetGeneratorTest.php b/test/Generator/SubsetGeneratorTest.php
index abd7e367..1708e29b 100644
--- a/test/Generator/SubsetGeneratorTest.php
+++ b/test/Generator/SubsetGeneratorTest.php
@@ -10,7 +10,7 @@ protected function setUp()
         $this->universe = ['a', 'b', 'c', 'd', 'e'];
         $this->generator = new SubsetGenerator($this->universe);
         $this->size = 100;
-        $this->rand = 'rand';
+        $this->rand = new \Eris\Random\RandomRange(new \Eris\Random\RandSource());
     }
     
     public function testScalesGenerationSizeToTouchAllPossibleSubsets()
diff --git a/test/Generator/SuchThatGeneratorTest.php b/test/Generator/SuchThatGeneratorTest.php
index 0558f4c4..1a0a05fe 100644
--- a/test/Generator/SuchThatGeneratorTest.php
+++ b/test/Generator/SuchThatGeneratorTest.php
@@ -6,7 +6,7 @@ class SuchThatGeneratorTest extends \PHPUnit_Framework_TestCase
     protected function setUp()
     {
         $this->size = 10;
-        $this->rand = 'rand';
+        $this->rand = new \Eris\Random\RandomRange(new \Eris\Random\RandSource());
     }
     
     public function testGeneratesAGeneratedValueObject()
diff --git a/test/Generator/TupleGeneratorTest.php b/test/Generator/TupleGeneratorTest.php
index 20d6c77f..63e38120 100644
--- a/test/Generator/TupleGeneratorTest.php
+++ b/test/Generator/TupleGeneratorTest.php
@@ -7,7 +7,7 @@ protected function setUp()
     {
         $this->generatorForSingleElement = new ChooseGenerator(0, 100);
         $this->size = 10;
-        $this->rand = 'rand';
+        $this->rand = new \Eris\Random\RandomRange(new \Eris\Random\RandSource());
     }
 
     private function assertInSingleElementGenerator($value)
diff --git a/test/Generator/VectorGeneratorTest.php b/test/Generator/VectorGeneratorTest.php
index 6129a05d..49b6b8d3 100644
--- a/test/Generator/VectorGeneratorTest.php
+++ b/test/Generator/VectorGeneratorTest.php
@@ -13,7 +13,7 @@ protected function setUp()
             $acc = $acc + $item;
             return $acc;
         };
-        $this->rand = 'rand';
+        $this->rand = new \Eris\Random\RandomRange(new \Eris\Random\RandSource());
     }
 
     public function testGeneratesVectorWithGivenSizeAndElementsFromGivenGenerator()
diff --git a/test/Listener/LogTest.php b/test/Listener/LogTest.php
index cd743c8a..7c52cd2a 100644
--- a/test/Listener/LogTest.php
+++ b/test/Listener/LogTest.php
@@ -1,22 +1,24 @@
 <?php
 namespace Eris\Listener;
 
-use Eris\Generator\GeneratedValueSingle;
-
 class LogTest extends \PHPUnit_Framework_TestCase
 {
+    private $timezone;
     protected function setUp()
     {
-        $this->file = '/tmp/eris-log-unit-test.log';
+        $this->timezone = date_default_timezone_get();
+        $this->file = sys_get_temp_dir().'/eris-log-unit-test.log';
         $this->time = function () {
             return 1300000000;
         };
         $this->log = new Log($this->file, $this->time, 1234);
+        date_default_timezone_set('UTC');
     }
 
     public function tearDown()
     {
         $this->log->endPropertyVerification(null, null);
+        date_default_timezone_set($this->timezone);
     }
     
     public function testWritesALineForEachIterationShowingItsIndex()