diff --git a/src/Command/ApiSuiteCommand.php b/src/Command/ApiSuiteCommand.php
index 2b774e4..f59a18b 100644
--- a/src/Command/ApiSuiteCommand.php
+++ b/src/Command/ApiSuiteCommand.php
@@ -21,6 +21,7 @@
 use SlayerBirden\DFCodeGeneration\Generator\Tests\Get as TestGet;
 use SlayerBirden\DFCodeGeneration\Generator\Tests\Gets as TestGets;
 use SlayerBirden\DFCodeGeneration\Generator\Tests\IdRegistry;
+use SlayerBirden\DFCodeGeneration\Generator\Tests\NullValuesRandomizer;
 use SlayerBirden\DFCodeGeneration\Generator\Tests\ReflectionProviderFactory;
 use SlayerBirden\DFCodeGeneration\Generator\Tests\Update as TestUpdate;
 use SlayerBirden\DFCodeGeneration\Generator\Factory\SimpleProvider;
@@ -116,13 +117,15 @@ protected function execute(InputInterface $input, OutputInterface $output)
     private function generateTests(): void
     {
         $entityProviderFactory = new ReflectionProviderFactory(new IdRegistry());
+        // 50% null values written by default
+        $randomizer = new NullValuesRandomizer(.5);
 
         $files = [];
-        $files[] = (new TestAdd($this->entityClassName, $entityProviderFactory))->generate();
-        $files[] = (new TestDelete($this->entityClassName, $entityProviderFactory))->generate();
-        $files[] = (new TestGet($this->entityClassName, $entityProviderFactory))->generate();
-        $files[] = (new TestGets($this->entityClassName, $entityProviderFactory))->generate();
-        $files[] = (new TestUpdate($this->entityClassName, $entityProviderFactory))->generate();
+        $files[] = (new TestAdd($this->entityClassName, $entityProviderFactory, $randomizer))->generate();
+        $files[] = (new TestDelete($this->entityClassName, $entityProviderFactory, $randomizer))->generate();
+        $files[] = (new TestGet($this->entityClassName, $entityProviderFactory, $randomizer))->generate();
+        $files[] = (new TestGets($this->entityClassName, $entityProviderFactory, $randomizer))->generate();
+        $files[] = (new TestUpdate($this->entityClassName, $entityProviderFactory, $randomizer))->generate();
 
         array_walk($files, function ($contents) {
             $this->writer->write($contents);
diff --git a/src/Generator/Tests/AbstractTest.php b/src/Generator/Tests/AbstractTest.php
index d66b0f3..f9a72c2 100644
--- a/src/Generator/Tests/AbstractTest.php
+++ b/src/Generator/Tests/AbstractTest.php
@@ -22,19 +22,18 @@ abstract class AbstractTest implements GeneratorInterface
     private $innerProviders = [];
     private $appended = [];
     /**
-     * The default probability of Nulled values being filled with data
-     * @var float
+     * @var NullValuesRandomizer
      */
-    private $probabilityOfFilledNullable;
+    private $nullValuesRandomizer;
 
     public function __construct(
         string $entityClassName,
         EntityProviderFactoryInterface $entityProviderFactory,
-        float $probabilityOfFilledNullable = .5
+        NullValuesRandomizer $nullValuesRandomizer
     ) {
         $this->entityProviderFactory = $entityProviderFactory;
         $this->entityClassName = $entityClassName;
-        $this->probabilityOfFilledNullable = $probabilityOfFilledNullable;
+        $this->nullValuesRandomizer = $nullValuesRandomizer;
     }
 
     protected function getLatestProvider()
@@ -87,8 +86,7 @@ private function getHaveInRepoPhrase(EntityProviderInterface $provider): string
             $type = $item['type'];
             $reference = $item['reference'] ?? [];
             $nullable = $item['nullable'] ?? false;
-            // Skip 50% of nullable values (by default)
-            if ($nullable && rand(0,100)/100 > $this->probabilityOfFilledNullable) {
+            if ($nullable && !$this->nullValuesRandomizer->ifShouldWrite()) {
                 continue;
             }
             if ($reference) {
diff --git a/src/Generator/Tests/NullValuesRandomizer.php b/src/Generator/Tests/NullValuesRandomizer.php
new file mode 100644
index 0000000..707ad59
--- /dev/null
+++ b/src/Generator/Tests/NullValuesRandomizer.php
@@ -0,0 +1,25 @@
+<?php
+declare(strict_types=1);
+
+namespace SlayerBirden\DFCodeGeneration\Generator\Tests;
+
+class NullValuesRandomizer
+{
+    /**
+     * @var float
+     */
+    private $probabilityOfFilledNull;
+
+    public function __construct(float $probabilityOfFilledNull)
+    {
+        $this->probabilityOfFilledNull = $probabilityOfFilledNull;
+    }
+
+    /**
+     * @return bool
+     */
+    public function ifShouldWrite(): bool
+    {
+        return rand(0,100)/100 < $this->probabilityOfFilledNull;
+    }
+}
diff --git a/tests/unit/Generator/Tests/AddTest.php b/tests/unit/Generator/Tests/AddTest.php
index ff53a43..1315ff2 100644
--- a/tests/unit/Generator/Tests/AddTest.php
+++ b/tests/unit/Generator/Tests/AddTest.php
@@ -57,7 +57,7 @@ public function testCreateClass()
         $this->provider->hasUnique()->willReturn(true);
         $this->provider->getIdName()->willReturn('id');
 
-        $add = new Add('Dummy\\User', $this->factory->reveal());
+        $add = new Add('Dummy\\User', $this->factory->reveal(), new NullValuesRandomizer(.5));
 
         $code = $add->generate();
         $this->assertNotEmpty($code);
diff --git a/tests/unit/Generator/Tests/BeforeTest.php b/tests/unit/Generator/Tests/BeforeTest.php
index 484081f..9a3b040 100644
--- a/tests/unit/Generator/Tests/BeforeTest.php
+++ b/tests/unit/Generator/Tests/BeforeTest.php
@@ -149,9 +149,8 @@ public function testManyToOne()
 
 BODY;
 
-        $actual = (new class('Dummy\\User', $this->getFactory()) extends AbstractTest
+        $actual = (new class('Dummy\\User', $this->getFactory(), new NullValuesRandomizer(.5)) extends AbstractTest
         {
-
             public function generate(): string
             {
                 return $this->generateHaveInRepo();
@@ -224,7 +223,7 @@ public function testManyToOneMultiple()
 
 BODY;
 
-        $actual = (new class('Dummy\\User', $this->getFactory(), 2) extends AbstractTest
+        $actual = (new class('Dummy\\User', $this->getFactory(), new NullValuesRandomizer(.5), 2) extends AbstractTest
         {
             /**
              * @var int
@@ -234,9 +233,10 @@ public function testManyToOneMultiple()
             public function __construct(
                 string $entityClassName,
                 EntityProviderFactoryInterface $entityProviderFactory,
+                NullValuesRandomizer $randomizer,
                 int $times
             ) {
-                parent::__construct($entityClassName, $entityProviderFactory);
+                parent::__construct($entityClassName, $entityProviderFactory, $randomizer);
                 $this->times = $times;
             }
 
@@ -319,7 +319,7 @@ public function testManyToManyMultiple()
         ]);
         $this->providers[] = $provider4;
 
-        $actual = (new class('Dummy\\User', $this->getFactory(), 2) extends AbstractTest
+        $actual = (new class('Dummy\\User', $this->getFactory(), new NullValuesRandomizer(.5), 2) extends AbstractTest
         {
             /**
              * @var int
@@ -329,9 +329,10 @@ public function testManyToManyMultiple()
             public function __construct(
                 string $entityClassName,
                 EntityProviderFactoryInterface $entityProviderFactory,
+                NullValuesRandomizer $randomizer,
                 int $times
             ) {
-                parent::__construct($entityClassName, $entityProviderFactory);
+                parent::__construct($entityClassName, $entityProviderFactory, $randomizer);
                 $this->times = $times;
             }
 
@@ -399,7 +400,7 @@ public function testRelationsNullable()
         $provider1 = $this->providers[0];
         $provider1->getEntitySpec()->willReturn($spec);
 
-        $actual = (new class('Dummy\\User', $this->getFactory(), .0) extends AbstractTest
+        $actual = (new class('Dummy\\User', $this->getFactory(), new NullValuesRandomizer(.0)) extends AbstractTest
         {
 
             public function generate(): string
@@ -454,7 +455,7 @@ public function testNullableColumn()
         $provider1 = $this->providers[0];
         $provider1->getEntitySpec()->willReturn($spec);
 
-        $actual = (new class('Dummy\\User', $this->getFactory(), .0) extends AbstractTest
+        $actual = (new class('Dummy\\User', $this->getFactory(), new NullValuesRandomizer(.0)) extends AbstractTest
         {
 
             public function generate(): string
diff --git a/tests/unit/Generator/Tests/DeleteTest.php b/tests/unit/Generator/Tests/DeleteTest.php
index 69f84bd..7b63c06 100644
--- a/tests/unit/Generator/Tests/DeleteTest.php
+++ b/tests/unit/Generator/Tests/DeleteTest.php
@@ -57,7 +57,7 @@ public function testCreateClass()
         $this->provider->hasUnique()->willReturn(true);
         $this->provider->getIdName()->willReturn('id');
 
-        $delete = new Delete('Dummy\\User', $this->factory->reveal());
+        $delete = new Delete('Dummy\\User', $this->factory->reveal(), new NullValuesRandomizer(.5));
 
         $code = $delete->generate();
         $this->assertNotEmpty($code);
diff --git a/tests/unit/Generator/Tests/GetTest.php b/tests/unit/Generator/Tests/GetTest.php
index 30e0478..c723272 100644
--- a/tests/unit/Generator/Tests/GetTest.php
+++ b/tests/unit/Generator/Tests/GetTest.php
@@ -57,7 +57,7 @@ public function testCreateClass()
         $this->provider->hasUnique()->willReturn(true);
         $this->provider->getIdName()->willReturn('id');
 
-        $get = new Get('Dummy\\User', $this->factory->reveal());
+        $get = new Get('Dummy\\User', $this->factory->reveal(), new NullValuesRandomizer(.5));
 
         $code = $get->generate();
         $this->assertNotEmpty($code);
diff --git a/tests/unit/Generator/Tests/GetsTest.php b/tests/unit/Generator/Tests/GetsTest.php
index c79a2ce..ada8254 100644
--- a/tests/unit/Generator/Tests/GetsTest.php
+++ b/tests/unit/Generator/Tests/GetsTest.php
@@ -57,7 +57,7 @@ public function testCreateClass()
         $this->provider->hasUnique()->willReturn(true);
         $this->provider->getIdName()->willReturn('id');
 
-        $gets = new Gets('Dummy\\User', $this->factory->reveal());
+        $gets = new Gets('Dummy\\User', $this->factory->reveal(), new NullValuesRandomizer(.5));
         $code = $gets->generate();
         $this->assertNotEmpty($code);
 
diff --git a/tests/unit/Generator/Tests/NullValuesRandomizerTest.php b/tests/unit/Generator/Tests/NullValuesRandomizerTest.php
new file mode 100644
index 0000000..59ca053
--- /dev/null
+++ b/tests/unit/Generator/Tests/NullValuesRandomizerTest.php
@@ -0,0 +1,50 @@
+<?php
+declare(strict_types=1);
+
+namespace SlayerBirden\DFCodeGeneration\Generator\Tests;
+
+use PHPUnit\Framework\TestCase;
+
+class NullValuesRandomizerTest extends TestCase
+{
+    /**
+     * @dataProvider percentageProvider
+     *
+     * @param float $percentage
+     */
+    public function testPercentage(float $percentage)
+    {
+        $randomizer = new NullValuesRandomizer($percentage);
+        $hits = 0;
+        $total = 1000000;
+        for ($i = 0; $i < $total; ++$i) {
+            $randomizer->ifShouldWrite() ? ++$hits : null;
+        }
+
+        $expected = (int)($percentage * 100);
+        $actual = round($hits / $total * 100);
+
+        $this->assertThat($actual, new RangeConstraint($expected - 1, $expected + 1));
+    }
+
+    public function testThatZeroNeverCalled()
+    {
+        $randomizer = new NullValuesRandomizer(.0);
+
+        $hits = 0;
+        for ($i = 0; $i < 1000000; ++$i) {
+            $randomizer->ifShouldWrite() ? ++$hits : null;
+        }
+
+        $this->assertSame(0, $hits);
+    }
+
+    public function percentageProvider(): array
+    {
+        return [
+            [.1],
+            [.5],
+            [.0],
+        ];
+    }
+}
diff --git a/tests/unit/Generator/Tests/RangeConstraint.php b/tests/unit/Generator/Tests/RangeConstraint.php
new file mode 100644
index 0000000..f9fbfad
--- /dev/null
+++ b/tests/unit/Generator/Tests/RangeConstraint.php
@@ -0,0 +1,54 @@
+<?php
+declare(strict_types=1);
+
+namespace SlayerBirden\DFCodeGeneration\Generator\Tests;
+
+use PHPUnit\Framework\Constraint\Constraint;
+
+class RangeConstraint extends Constraint
+{
+    /**
+     * @var int
+     */
+    private $from;
+    /**
+     * @var int
+     */
+    private $to;
+
+    public function __construct(int $from, int $to)
+    {
+        parent::__construct();
+        $this->from = $from;
+        $this->to = $to;
+    }
+
+    /**
+     * @inheritdoc
+     */
+    public function toString(): string
+    {
+        return 'in range';
+    }
+
+    /**
+     * @inheritdoc
+     */
+    protected function matches($other): bool
+    {
+        return $other >= $this->from && $other <= $this->to;
+    }
+
+    /**
+     * @inheritdoc
+     */
+    protected function failureDescription($other): string
+    {
+        return \sprintf(
+            '%s is not in range between %s and %s',
+            $this->exporter->shortenedExport($other),
+            $this->from,
+            $this->to
+        );
+    }
+}
diff --git a/tests/unit/Generator/Tests/UpdateTest.php b/tests/unit/Generator/Tests/UpdateTest.php
index fe8c4d8..0f24258 100644
--- a/tests/unit/Generator/Tests/UpdateTest.php
+++ b/tests/unit/Generator/Tests/UpdateTest.php
@@ -60,7 +60,7 @@ public function testCreateClass()
         $this->provider->hasUnique()->willReturn(true);
         $this->provider->getIdName()->willReturn('id');
 
-        $update = new Update('Dummy\\User', $this->factory->reveal());
+        $update = new Update('Dummy\\User', $this->factory->reveal(), new NullValuesRandomizer(.5));
 
         $code = $update->generate();
         $this->assertNotEmpty($code);