diff --git a/src/Result/Group.php b/src/Result/Group.php
index 2581c2a..571e14c 100644
--- a/src/Result/Group.php
+++ b/src/Result/Group.php
@@ -45,7 +45,7 @@ public function toArray(): array
         foreach ($this->metrics as $metric) {
             $metricsAsArray[$metric->identifier] = [
                 'title' => $metric->title,
-                'value' => $metric->value->format(),
+                'value' => $metric->value->getRaw(),
             ];
         }
 
diff --git a/src/Result/Metric/IntegerValue.php b/src/Result/Metric/IntegerValue.php
index cbe623c..d9ec612 100644
--- a/src/Result/Metric/IntegerValue.php
+++ b/src/Result/Metric/IntegerValue.php
@@ -4,6 +4,8 @@
 
 namespace Panaly\Result\Metric;
 
+use function number_format;
+
 final readonly class IntegerValue implements Value
 {
     public function __construct(public int $value)
@@ -12,11 +14,11 @@ public function __construct(public int $value)
 
     public function getRaw(): int
     {
-        return $this->format();
+        return $this->value;
     }
 
-    public function format(): int
+    public function format(): string
     {
-        return $this->value;
+        return number_format(num: $this->value);
     }
 }
diff --git a/tests/Collector/CollectorTest.php b/tests/Collector/CollectorTest.php
index 3a64e4d..8391bb8 100644
--- a/tests/Collector/CollectorTest.php
+++ b/tests/Collector/CollectorTest.php
@@ -47,10 +47,12 @@ public function testCollectingMetricsWithResults(): void
         self::assertCount(2, $metrics);
 
         self::assertSame('I am a default title', $metrics[0]->title);
-        self::assertSame(12, $metrics[0]->value->format());
+        self::assertSame(12, $metrics[0]->value->getRaw());
+        self::assertSame('12', $metrics[0]->value->format());
 
         self::assertSame('I am a default title', $metrics[1]->title);
-        self::assertSame(12, $metrics[1]->value->format());
+        self::assertSame(12, $metrics[1]->value->getRaw());
+        self::assertSame('12', $metrics[1]->value->format());
     }
 
     public function testInvalidConfigurationFile(): void
diff --git a/tests/Result/GroupTest.php b/tests/Result/GroupTest.php
new file mode 100644
index 0000000..91b88e1
--- /dev/null
+++ b/tests/Result/GroupTest.php
@@ -0,0 +1,97 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Panaly\Test\Result;
+
+use Panaly\Result\Group;
+use Panaly\Result\Metric;
+use Panaly\Result\Metric\IntegerValue;
+use PHPUnit\Framework\TestCase;
+
+class GroupTest extends TestCase
+{
+    public function testGetTitle(): void
+    {
+        $group = new Group('identifier', 'title', []);
+        self::assertSame('title', $group->getTitle());
+    }
+
+    public function testGetIdentifier(): void
+    {
+        $group = new Group('identifier', 'title', []);
+        self::assertSame('identifier', $group->getIdentifier());
+    }
+
+    public function testAddMetric(): void
+    {
+        $group  = new Group('identifier', 'title', []);
+        $metric = new Metric('metric1', 'Metric 1', new IntegerValue(100));
+        $group->addMetric($metric);
+
+        self::assertCount(1, $group->getMetrics());
+        self::assertSame($metric, $group->getMetrics()[0]);
+    }
+
+    public function testToArrayWithEmptyMetrics(): void
+    {
+        $group    = new Group('identifier', 'title', []);
+        $expected = [
+            'title' => 'title',
+            'metrics' => [],
+        ];
+
+        self::assertSame($expected, $group->toArray());
+    }
+
+    public function testToArrayWithSingleMetric(): void
+    {
+        $metric   = new Metric('metric1', 'Metric 1', new IntegerValue(100));
+        $group    = new Group('identifier', 'title', [$metric]);
+        $expected = [
+            'title' => 'title',
+            'metrics' => [
+                'metric1' => [
+                    'title' => 'Metric 1',
+                    'value' => 100,
+                ],
+            ],
+        ];
+
+        self::assertSame($expected, $group->toArray());
+    }
+
+    public function testToArrayWithMultipleMetrics(): void
+    {
+        $metric1  = new Metric('metric1', 'Metric 1', new IntegerValue(10000));
+        $metric2  = new Metric('metric2', 'Metric 2', new IntegerValue(20000));
+        $group    = new Group('identifier', 'title', [$metric1, $metric2]);
+        $expected = [
+            'title' => 'title',
+            'metrics' => [
+                'metric1' => [
+                    'title' => 'Metric 1',
+                    'value' => 10000,
+                ],
+                'metric2' => [
+                    'title' => 'Metric 2',
+                    'value' => 20000,
+                ],
+            ],
+        ];
+
+        self::assertSame($expected, $group->toArray());
+    }
+
+    public function testGetMetrics(): void
+    {
+        $metric1 = new Metric('metric1', 'Metric 1', new IntegerValue(100));
+        $metric2 = new Metric('metric2', 'Metric 2', new IntegerValue(200));
+        $group   = new Group('identifier', 'title', [$metric1, $metric2]);
+
+        $metrics = $group->getMetrics();
+        self::assertCount(2, $metrics);
+        self::assertSame($metric1, $metrics[0]);
+        self::assertSame($metric2, $metrics[1]);
+    }
+}
diff --git a/tests/Result/ResultTest.php b/tests/Result/ResultTest.php
index c475e6a..72f6f64 100644
--- a/tests/Result/ResultTest.php
+++ b/tests/Result/ResultTest.php
@@ -5,6 +5,7 @@
 namespace Panaly\Test\Result;
 
 use DateTimeInterface;
+use Panaly\Result\Group;
 use Panaly\Result\Result;
 use PHPUnit\Framework\TestCase;
 
@@ -19,4 +20,47 @@ public function testTheResultConvertedToArrayContainsACreationDateTime(): void
         self::assertIsString($resultAsArray['createdAt']);
         self::assertSame($result->getCreateAt()->format(DateTimeInterface::ATOM), $resultAsArray['createdAt']);
     }
+
+    public function testAddGroup(): void
+    {
+        $result = new Result();
+        $group  = new Group('identifier', 'title', []);
+        $result->addGroup($group);
+
+        self::assertCount(1, $result->getGroups());
+        self::assertSame($group, $result->getGroups()[0]);
+    }
+
+    public function testGetGroups(): void
+    {
+        $group1 = new Group('identifier1', 'title1', []);
+        $group2 = new Group('identifier2', 'title2', []);
+        $result = new Result();
+        $result->addGroup($group1);
+        $result->addGroup($group2);
+
+        $groups = $result->getGroups();
+        self::assertCount(2, $groups);
+        self::assertSame($group1, $groups[0]);
+        self::assertSame($group2, $groups[1]);
+    }
+
+    public function testToArrayWithGroups(): void
+    {
+        $group1 = new Group('identifier1', 'title1', []);
+        $group2 = new Group('identifier2', 'title2', []);
+        $result = new Result();
+        $result->addGroup($group1);
+        $result->addGroup($group2);
+
+        $resultAsArray = $result->toArray();
+        self::assertArrayHasKey('groups', $resultAsArray);
+        self::assertCount(2, $resultAsArray['groups']);
+
+        self::assertArrayHasKey('identifier1', $resultAsArray['groups']);
+        self::assertArrayHasKey('identifier2', $resultAsArray['groups']);
+
+        self::assertSame($group1->toArray(), $resultAsArray['groups']['identifier1']);
+        self::assertSame($group2->toArray(), $resultAsArray['groups']['identifier2']);
+    }
 }