diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index c02b873..d99ab21 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -17,6 +17,23 @@ jobs:
       - uses: ramsey/composer-install@v3
       - run: composer phpunit
 
+  code-coverage:
+    name: Code Coverage
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v6
+      - uses: shivammathur/setup-php@v2
+        with:
+          php-version: '8.5'
+          coverage: pcov
+      - uses: ramsey/composer-install@v3
+      - name: Generate coverage report
+        run: vendor/bin/phpunit --coverage-clover=coverage.xml
+      - name: Upload to Codecov
+        uses: codecov/codecov-action@v5
+        with:
+          token: ${{ secrets.CODECOV_TOKEN }}
+
   static-analysis:
     name: Static Analysis
     runs-on: ubuntu-latest
@@ -26,4 +43,5 @@ jobs:
         with:
           php-version: '8.5'
       - uses: ramsey/composer-install@v3
+      - run: composer phpcs
       - run: composer phpstan
diff --git a/composer.json b/composer.json
index daaa710..e47b065 100644
--- a/composer.json
+++ b/composer.json
@@ -40,6 +40,7 @@
         }
     },
     "scripts": {
+        "coverage": "vendor/bin/phpunit --coverage-text",
         "phpcs": "vendor/bin/phpcs",
         "phpstan": "vendor/bin/phpstan analyze",
         "phpunit": "vendor/bin/phpunit",
diff --git a/tests/AbstractMapperTest.php b/tests/AbstractMapperTest.php
index 29ea259..fd7cfbd 100644
--- a/tests/AbstractMapperTest.php
+++ b/tests/AbstractMapperTest.php
@@ -9,6 +9,10 @@
 use PHPUnit\Framework\TestCase;
 use ReflectionObject;
 use Respect\Data\Collections\Collection;
+use Respect\Data\Styles\CakePHP;
+use Respect\Data\Styles\Standard;
+use SplObjectStorage;
+use stdClass;
 
 #[CoversClass(AbstractMapper::class)]
 class AbstractMapperTest extends TestCase
@@ -82,4 +86,130 @@ public function magicGetterShouldBypassToCollection(): void
         $expected->setMapper($this->mapper);
         $this->assertEquals($expected->bar->baz, $collection);
     }
+
+    #[Test]
+    public function getStyleShouldReturnDefaultStandard(): void
+    {
+        $style = $this->mapper->getStyle();
+        $this->assertInstanceOf(Standard::class, $style);
+    }
+
+    #[Test]
+    public function getStyleShouldReturnSameInstanceOnSubsequentCalls(): void
+    {
+        $style1 = $this->mapper->getStyle();
+        $style2 = $this->mapper->getStyle();
+        $this->assertSame($style1, $style2);
+    }
+
+    #[Test]
+    public function setStyleShouldChangeStyle(): void
+    {
+        $style = new CakePHP();
+        $result = $this->mapper->setStyle($style);
+        $this->assertSame($style, $this->mapper->getStyle());
+        $this->assertSame($this->mapper, $result);
+    }
+
+    #[Test]
+    public function persistShouldMarkObjectAsTracked(): void
+    {
+        $entity = new stdClass();
+        $collection = Collection::foo();
+        $this->mapper->persist($entity, $collection);
+        $this->assertTrue($this->mapper->isTracked($entity));
+    }
+
+    #[Test]
+    public function persistAlreadyTrackedShouldReturnTrue(): void
+    {
+        $entity = new stdClass();
+        $collection = Collection::foo();
+        $this->mapper->markTracked($entity, $collection);
+        $result = $this->mapper->persist($entity, $collection);
+        $this->assertTrue($result);
+    }
+
+    #[Test]
+    public function removeShouldMarkObjectAsTracked(): void
+    {
+        $entity = new stdClass();
+        $collection = Collection::foo();
+        $result = $this->mapper->remove($entity, $collection);
+        $this->assertTrue($result);
+        $this->assertTrue($this->mapper->isTracked($entity));
+    }
+
+    #[Test]
+    public function removeAlreadyTrackedShouldReturnTrue(): void
+    {
+        $entity = new stdClass();
+        $collection = Collection::foo();
+        $this->mapper->markTracked($entity, $collection);
+        $result = $this->mapper->remove($entity, $collection);
+        $this->assertTrue($result);
+    }
+
+    #[Test]
+    public function isTrackedShouldReturnFalseForUntrackedEntity(): void
+    {
+        $this->assertFalse($this->mapper->isTracked(new stdClass()));
+    }
+
+    #[Test]
+    public function markTrackedShouldReturnTrue(): void
+    {
+        $entity = new stdClass();
+        $collection = Collection::foo();
+        $this->assertTrue($this->mapper->markTracked($entity, $collection));
+    }
+
+    #[Test]
+    public function resetShouldClearChangedRemovedAndNew(): void
+    {
+        $entity = new stdClass();
+        $collection = Collection::foo();
+        $this->mapper->persist($entity, $collection);
+        $this->mapper->remove($entity, $collection);
+        $this->mapper->reset();
+
+        $ref = new ReflectionObject($this->mapper);
+
+        $newProp = $ref->getProperty('new');
+        /** @var SplObjectStorage<object, mixed> $newStorage */
+        $newStorage = $newProp->getValue($this->mapper);
+        $this->assertCount(0, $newStorage);
+
+        $changedProp = $ref->getProperty('changed');
+        /** @var SplObjectStorage<object, mixed> $changedStorage */
+        $changedStorage = $changedProp->getValue($this->mapper);
+        $this->assertCount(0, $changedStorage);
+
+        $removedProp = $ref->getProperty('removed');
+        /** @var SplObjectStorage<object, mixed> $removedStorage */
+        $removedStorage = $removedProp->getValue($this->mapper);
+        $this->assertCount(0, $removedStorage);
+    }
+
+    #[Test]
+    public function issetShouldReturnTrueForRegisteredCollection(): void
+    {
+        $coll = Collection::foo();
+        $this->mapper->registerCollection('my_alias', $coll);
+        $this->assertTrue(isset($this->mapper->my_alias));
+    }
+
+    #[Test]
+    public function issetShouldReturnFalseForUnregisteredCollection(): void
+    {
+        $this->assertFalse(isset($this->mapper->nonexistent));
+    }
+
+    #[Test]
+    public function magicGetShouldReturnNewCollectionWhenNotRegistered(): void
+    {
+        $coll = $this->mapper->unregistered;
+        $this->assertInstanceOf(Collection::class, $coll);
+        $this->assertEquals('unregistered', $coll->getName());
+    }
 }
diff --git a/tests/CollectionIteratorTest.php b/tests/CollectionIteratorTest.php
index be84d73..04429ca 100644
--- a/tests/CollectionIteratorTest.php
+++ b/tests/CollectionIteratorTest.php
@@ -89,4 +89,12 @@ public function getChildrenUseCollectionNext(): void
         $iterator = new CollectionIterator($coll);
         $this->assertTrue($iterator->hasChildren());
     }
+
+    #[Test]
+    public function recursiveTraversalShouldVisitNextChain(): void
+    {
+        $coll = Collection::foo()->bar->baz;
+        $items = iterator_to_array(CollectionIterator::recursive($coll));
+        $this->assertCount(3, $items);
+    }
 }
diff --git a/tests/Collections/CollectionTest.php b/tests/Collections/CollectionTest.php
index a70d4c9..8986c30 100644
--- a/tests/Collections/CollectionTest.php
+++ b/tests/Collections/CollectionTest.php
@@ -297,4 +297,85 @@ public function fetchAllOnCollectionShouldExceptionIfMapperDontExist(): void
         $this->expectException(RuntimeException::class);
         Collection::foo()->fetchAll();
     }
+
+    #[Test]
+    public function usingShouldCreateCollectionWithCondition(): void
+    {
+        $coll = Collection::using(42);
+        $this->assertInstanceOf(Collection::class, $coll);
+        $this->assertEquals(42, $coll->getCondition());
+    }
+
+    #[Test]
+    public function haveShouldReturnFalseForMissingExtra(): void
+    {
+        $coll = new Collection('foo');
+        $this->assertFalse($coll->have('nonexistent'));
+    }
+
+    #[Test]
+    public function haveShouldReturnTrueForExistingExtra(): void
+    {
+        $coll = new Collection('foo');
+        $coll->extra('key', 'value');
+        $this->assertTrue($coll->have('key'));
+    }
+
+    #[Test]
+    public function getExtraShouldReturnNullForMissingExtra(): void
+    {
+        $coll = new Collection('foo');
+        $this->assertNull($coll->getExtra('nonexistent'));
+    }
+
+    #[Test]
+    public function getExtraShouldReturnValueForExistingExtra(): void
+    {
+        $coll = new Collection('foo');
+        $coll->extra('key', 'value');
+        $this->assertEquals('value', $coll->getExtra('key'));
+    }
+
+    #[Test]
+    public function extraShouldReturnSelf(): void
+    {
+        $coll = new Collection('foo');
+        $result = $coll->extra('key', 'value');
+        $this->assertSame($coll, $result);
+    }
+
+    #[Test]
+    public function getParentNameShouldReturnNullWhenNoParent(): void
+    {
+        $coll = new Collection('foo');
+        $this->assertNull($coll->getParentName());
+    }
+
+    #[Test]
+    public function getNextNameShouldReturnNullWhenNoNext(): void
+    {
+        $coll = new Collection('foo');
+        $this->assertNull($coll->getNextName());
+    }
+
+    #[Test]
+    public function hasNextShouldReturnFalseWhenNoNext(): void
+    {
+        $coll = new Collection('foo');
+        $this->assertFalse($coll->hasNext());
+    }
+
+    #[Test]
+    public function magicGetShouldUseRegisteredCollectionFromMapper(): void
+    {
+        $registered = Collection::bar();
+        $mapperMock = $this->createMock(AbstractMapper::class);
+        $mapperMock->method('__isset')->with('bar')->willReturn(true);
+        $mapperMock->method('__get')->with('bar')->willReturn($registered);
+
+        $coll = new Collection('foo');
+        $coll->setMapper($mapperMock);
+        $result = $coll->bar;
+        $this->assertEquals('bar', $result->getNextName());
+    }
 }
diff --git a/tests/Collections/FilteredTest.php b/tests/Collections/FilteredTest.php
index 69331e3..3fdc4bd 100644
--- a/tests/Collections/FilteredTest.php
+++ b/tests/Collections/FilteredTest.php
@@ -28,4 +28,13 @@ public function collectionCanBeCreatedStaticallyWithChildren(): void
         $this->assertEquals(['bar'], $children1->getExtra('filters'));
         $this->assertEquals(['bat'], $children2->getExtra('filters'));
     }
+
+    #[Test]
+    public function callStaticShouldCreateFilteredCollectionWithName(): void
+    {
+        $coll = Filtered::items();
+        $this->assertInstanceOf(Filtered::class, $coll);
+        $this->assertEquals('items', $coll->getName());
+        $this->assertEquals([], $coll->getExtra('filters'));
+    }
 }
diff --git a/tests/Collections/MixedTest.php b/tests/Collections/MixedTest.php
index 7205ded..6bee40e 100644
--- a/tests/Collections/MixedTest.php
+++ b/tests/Collections/MixedTest.php
@@ -28,4 +28,13 @@ public function collectionCanBeCreatedStaticallyWithChildren(): void
         $this->assertEquals(['foo' => ['bar']], $children1->getExtra('mixins'));
         $this->assertEquals(['bat' => ['bar']], $children2->getExtra('mixins'));
     }
+
+    #[Test]
+    public function callStaticShouldCreateMixCollectionWithName(): void
+    {
+        $coll = Mix::items();
+        $this->assertInstanceOf(Mix::class, $coll);
+        $this->assertEquals('items', $coll->getName());
+        $this->assertEquals([], $coll->getExtra('mixins'));
+    }
 }
diff --git a/tests/Collections/TypedTest.php b/tests/Collections/TypedTest.php
index f95f56d..5d65c3e 100644
--- a/tests/Collections/TypedTest.php
+++ b/tests/Collections/TypedTest.php
@@ -28,4 +28,13 @@ public function collectionCanBeCreatedStaticallyWithChildren(): void
         $this->assertEquals('a', $children1->getExtra('type'));
         $this->assertEquals('b', $children2->getExtra('type'));
     }
+
+    #[Test]
+    public function callStaticShouldCreateTypedCollectionWithName(): void
+    {
+        $coll = Typed::items();
+        $this->assertInstanceOf(Typed::class, $coll);
+        $this->assertEquals('items', $coll->getName());
+        $this->assertEquals('', $coll->getExtra('type'));
+    }
 }
diff --git a/tests/Styles/AbstractStyleTest.php b/tests/Styles/AbstractStyleTest.php
index d45c541..e962f96 100644
--- a/tests/Styles/AbstractStyleTest.php
+++ b/tests/Styles/AbstractStyleTest.php
@@ -114,4 +114,16 @@ public function testCamelCaseToSeparatorAndViceVersa(
             $separatorToCamelCaseMethod->invoke($this->style, $separated, $separator),
         );
     }
+
+    public function testPluralToSingularReturnsUnchangedWhenNoMatch(): void
+    {
+        $method = new ReflectionMethod($this->style, 'pluralToSingular');
+        $this->assertEquals('fox', $method->invoke($this->style, 'fox'));
+    }
+
+    public function testSingularToPluralReturnsUnchangedWhenNoMatch(): void
+    {
+        $method = new ReflectionMethod($this->style, 'singularToPlural');
+        $this->assertEquals('news', $method->invoke($this->style, 'news'));
+    }
 }
diff --git a/tests/Styles/CakePHP/CakePHPIntegrationTest.php b/tests/Styles/CakePHP/CakePHPIntegrationTest.php
index e9b881e..0620ac2 100644
--- a/tests/Styles/CakePHP/CakePHPIntegrationTest.php
+++ b/tests/Styles/CakePHP/CakePHPIntegrationTest.php
@@ -9,7 +9,6 @@
 use Respect\Data\InMemoryMapper;
 use Respect\Data\Styles\CakePHP;
 
-#[CoversClass(InMemoryMapper::class)]
 #[CoversClass(CakePHP::class)]
 class CakePHPIntegrationTest extends TestCase
 {
diff --git a/tests/Styles/NorthWind/NorthWindIntegrationTest.php b/tests/Styles/NorthWind/NorthWindIntegrationTest.php
index 512a371..948fb4d 100644
--- a/tests/Styles/NorthWind/NorthWindIntegrationTest.php
+++ b/tests/Styles/NorthWind/NorthWindIntegrationTest.php
@@ -9,7 +9,6 @@
 use Respect\Data\InMemoryMapper;
 use Respect\Data\Styles\NorthWind;
 
-#[CoversClass(InMemoryMapper::class)]
 #[CoversClass(NorthWind::class)]
 class NorthWindIntegrationTest extends TestCase
 {
diff --git a/tests/Styles/Plural/PluralIntegrationTest.php b/tests/Styles/Plural/PluralIntegrationTest.php
index 0911a5e..14521db 100644
--- a/tests/Styles/Plural/PluralIntegrationTest.php
+++ b/tests/Styles/Plural/PluralIntegrationTest.php
@@ -9,7 +9,6 @@
 use Respect\Data\InMemoryMapper;
 use Respect\Data\Styles\Plural;
 
-#[CoversClass(InMemoryMapper::class)]
 #[CoversClass(Plural::class)]
 class PluralIntegrationTest extends TestCase
 {
diff --git a/tests/Styles/Sakila/SakilaIntegrationTest.php b/tests/Styles/Sakila/SakilaIntegrationTest.php
index ed52e8f..5c1422b 100644
--- a/tests/Styles/Sakila/SakilaIntegrationTest.php
+++ b/tests/Styles/Sakila/SakilaIntegrationTest.php
@@ -9,7 +9,6 @@
 use Respect\Data\InMemoryMapper;
 use Respect\Data\Styles\Sakila;
 
-#[CoversClass(InMemoryMapper::class)]
 #[CoversClass(Sakila::class)]
 class SakilaIntegrationTest extends TestCase
 {