Add comprehensive unit tests for DistanceCalculator

- Test all distance strategies (cosine, angular, euclidean, manhattan, chebyshev)
- Test with various vector dimensions and configurations
- Test maxItems limiting functionality
- Test edge cases (empty arrays, single documents, negative values)
- Achieve full test coverage for the DistanceCalculator class

Author: OskarStark

src/store/tests/Bridge/Local/DistanceCalculatorTest.php

@@ -0,0 +1,302 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <[email protected]>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\AI\Store\Tests\Bridge\Local;
+
+use PHPUnit\Framework\Attributes\CoversClass;
+use PHPUnit\Framework\Attributes\DataProvider;
+use PHPUnit\Framework\Attributes\TestDox;
+use PHPUnit\Framework\Attributes\UsesClass;
+use PHPUnit\Framework\TestCase;
+use Symfony\AI\Platform\Vector\Vector;
+use Symfony\AI\Store\Bridge\Local\DistanceCalculator;
+use Symfony\AI\Store\Bridge\Local\DistanceStrategy;
+use Symfony\AI\Store\Document\Metadata;
+use Symfony\AI\Store\Document\VectorDocument;
+use Symfony\Component\Uid\Uuid;
+
+#[CoversClass(DistanceCalculator::class)]
+#[UsesClass(VectorDocument::class)]
+#[UsesClass(Vector::class)]
+#[UsesClass(Metadata::class)]
+#[UsesClass(DistanceStrategy::class)]
+final class DistanceCalculatorTest extends TestCase
+{
+    /**
+     * @param array<list<float>> $documentVectors
+     * @param list<float>        $queryVector
+     * @param list<int>          $expectedOrder
+     */
+    #[TestDox('Calculates distances correctly using $strategy strategy')]
+    #[DataProvider('provideDistanceStrategyTestCases')]
+    public function testCalculateWithDifferentStrategies(
+        DistanceStrategy $strategy,
+        array $documentVectors,
+        array $queryVector,
+        array $expectedOrder,
+    ) {
+        $calculator = new DistanceCalculator($strategy);
+
+        $documents = [];
+        foreach ($documentVectors as $index => $vector) {
+            $documents[] = new VectorDocument(
+                Uuid::v4(),
+                new Vector($vector),
+                new Metadata(['index' => $index])
+            );
+        }
+
+        $result = $calculator->calculate($documents, new Vector($queryVector));
+
+        // Check that results are ordered correctly
+        $this->assertCount(\count($expectedOrder), $result);
+
+        foreach ($expectedOrder as $position => $expectedIndex) {
+            $metadata = $result[$position]->metadata;
+            $this->assertSame($expectedIndex, $metadata['index']);
+        }
+    }
+
+    /**
+     * @return \Generator<string, array{DistanceStrategy, array<list<float>>, list<float>, list<int>}>
+     */
+    public static function provideDistanceStrategyTestCases(): \Generator
+    {
+        // Test vectors for different scenarios
+        $vectors = [
+            [1.0, 0.0, 0.0],  // Index 0: unit vector along x-axis
+            [0.0, 1.0, 0.0],  // Index 1: unit vector along y-axis
+            [0.0, 0.0, 1.0],  // Index 2: unit vector along z-axis
+            [0.5, 0.5, 0.707], // Index 3: mixed vector
+        ];
+
+        $queryVector = [1.0, 0.0, 0.0]; // Query similar to first vector
+
+        yield 'cosine distance' => [
+            DistanceStrategy::COSINE_DISTANCE,
+            $vectors,
+            $queryVector,
+            [0, 3, 1, 2], // Expected order: 0 is most similar (same direction)
+        ];
+
+        yield 'euclidean distance' => [
+            DistanceStrategy::EUCLIDEAN_DISTANCE,
+            $vectors,
+            $queryVector,
+            [0, 3, 1, 2], // Expected order: 0 is closest
+        ];
+
+        yield 'manhattan distance' => [
+            DistanceStrategy::MANHATTAN_DISTANCE,
+            $vectors,
+            $queryVector,
+            [0, 3, 1, 2], // Expected order based on L1 distance
+        ];
+    }
+
+    #[TestDox('Limits results to specified maximum items')]
+    public function testCalculateWithMaxItems()
+    {
+        $calculator = new DistanceCalculator(DistanceStrategy::EUCLIDEAN_DISTANCE);
+
+        $documents = [
+            new VectorDocument(Uuid::v4(), new Vector([0.0, 0.0]), new Metadata(['id' => 'a'])),
+            new VectorDocument(Uuid::v4(), new Vector([1.0, 0.0]), new Metadata(['id' => 'b'])),
+            new VectorDocument(Uuid::v4(), new Vector([0.0, 1.0]), new Metadata(['id' => 'c'])),
+            new VectorDocument(Uuid::v4(), new Vector([1.0, 1.0]), new Metadata(['id' => 'd'])),
+            new VectorDocument(Uuid::v4(), new Vector([0.5, 0.5]), new Metadata(['id' => 'e'])),
+        ];
+
+        $queryVector = new Vector([0.0, 0.0]);
+
+        // Request only top 3 results
+        $result = $calculator->calculate($documents, $queryVector, 3);
+
+        $this->assertCount(3, $result);
+
+        // Verify the closest 3 documents are returned
+        // Distances from [0.0, 0.0]:
+        // a: [0.0, 0.0] -> 0.0
+        // b: [1.0, 0.0] -> 1.0
+        // c: [0.0, 1.0] -> 1.0
+        // d: [1.0, 1.0] -> sqrt(2) ≈ 1.414
+        // e: [0.5, 0.5] -> sqrt(0.5) ≈ 0.707
+
+        $ids = array_map(fn ($doc) => $doc->metadata['id'], $result);
+        $this->assertSame(['a', 'e', 'b'], $ids); // a is closest, then e, then b/c (same distance)
+    }
+
+    #[TestDox('Calculates cosine distance correctly for parallel vectors')]
+    public function testCosineDistanceCalculation()
+    {
+        $calculator = new DistanceCalculator(DistanceStrategy::COSINE_DISTANCE);
+
+        // Test with parallel vectors (should have cosine distance = 0)
+        $doc1 = new VectorDocument(Uuid::v4(), new Vector([1.0, 2.0, 3.0]));
+        $doc2 = new VectorDocument(Uuid::v4(), new Vector([2.0, 4.0, 6.0])); // Parallel to doc1
+
+        $queryVector = new Vector([1.0, 2.0, 3.0]);
+
+        $result = $calculator->calculate([$doc1, $doc2], $queryVector);
+
+        // Both vectors are parallel to query, so should have same cosine distance (0)
+        $this->assertCount(2, $result);
+    }
+
+    #[TestDox('Calculates angular distance correctly for orthogonal vectors')]
+    public function testAngularDistanceCalculation()
+    {
+        $calculator = new DistanceCalculator(DistanceStrategy::ANGULAR_DISTANCE);
+
+        // Orthogonal vectors should have angular distance of 0.5 (90 degrees / 180 degrees)
+        $orthogonalDoc = new VectorDocument(Uuid::v4(), new Vector([0.0, 1.0]));
+        $parallelDoc = new VectorDocument(Uuid::v4(), new Vector([2.0, 0.0]));
+
+        $queryVector = new Vector([1.0, 0.0]);
+
+        $result = $calculator->calculate([$orthogonalDoc, $parallelDoc], $queryVector);
+
+        // Parallel vector should be first (smaller angular distance)
+        $this->assertSame($parallelDoc, $result[0]);
+        $this->assertSame($orthogonalDoc, $result[1]);
+    }
+
+    #[TestDox('Calculates Chebyshev distance using maximum absolute difference')]
+    public function testChebyshevDistanceCalculation()
+    {
+        $calculator = new DistanceCalculator(DistanceStrategy::CHEBYSHEV_DISTANCE);
+
+        $doc1 = new VectorDocument(Uuid::v4(), new Vector([1.0, 2.0, 3.0]));
+        $doc2 = new VectorDocument(Uuid::v4(), new Vector([1.5, 2.5, 3.5]));
+        $doc3 = new VectorDocument(Uuid::v4(), new Vector([4.0, 2.0, 3.0]));
+
+        $queryVector = new Vector([1.0, 2.0, 3.0]);
+
+        $result = $calculator->calculate([$doc1, $doc2, $doc3], $queryVector);
+
+        // doc1 should be first (distance 0), doc2 second (max diff 0.5), doc3 last (max diff 3.0)
+        $this->assertSame($doc1, $result[0]);
+        $this->assertSame($doc2, $result[1]);
+        $this->assertSame($doc3, $result[2]);
+    }
+
+    #[TestDox('Returns empty array when no documents are provided')]
+    public function testEmptyDocumentsArray()
+    {
+        $calculator = new DistanceCalculator();
+
+        $result = $calculator->calculate([], new Vector([1.0, 2.0, 3.0]));
+
+        $this->assertSame([], $result);
+    }
+
+    #[TestDox('Returns single document when only one is provided')]
+    public function testSingleDocument()
+    {
+        $calculator = new DistanceCalculator();
+
+        $doc = new VectorDocument(Uuid::v4(), new Vector([1.0, 2.0, 3.0]));
+
+        $result = $calculator->calculate([$doc], new Vector([0.0, 0.0, 0.0]));
+
+        $this->assertCount(1, $result);
+        $this->assertSame($doc, $result[0]);
+    }
+
+    #[TestDox('Handles high-dimensional vectors correctly')]
+    public function testHighDimensionalVectors()
+    {
+        $calculator = new DistanceCalculator(DistanceStrategy::EUCLIDEAN_DISTANCE);
+
+        // Create high-dimensional vectors (100 dimensions)
+        $dimensions = 100;
+        $vector1 = array_fill(0, $dimensions, 0.1);
+        $vector2 = array_fill(0, $dimensions, 0.2);
+
+        $doc1 = new VectorDocument(Uuid::v4(), new Vector($vector1));
+        $doc2 = new VectorDocument(Uuid::v4(), new Vector($vector2));
+
+        $queryVector = new Vector(array_fill(0, $dimensions, 0.15));
+
+        $result = $calculator->calculate([$doc1, $doc2], $queryVector);
+
+        // doc1 should be closer to query vector (0.15 is closer to 0.1 than to 0.2)
+        $this->assertSame($doc1, $result[0]);
+        $this->assertSame($doc2, $result[1]);
+    }
+
+    #[TestDox('Handles negative vector components correctly')]
+    public function testNegativeVectorComponents()
+    {
+        $calculator = new DistanceCalculator(DistanceStrategy::EUCLIDEAN_DISTANCE);
+
+        $doc1 = new VectorDocument(Uuid::v4(), new Vector([-1.0, -2.0, -3.0]));
+        $doc2 = new VectorDocument(Uuid::v4(), new Vector([1.0, 2.0, 3.0]));
+        $doc3 = new VectorDocument(Uuid::v4(), new Vector([0.0, 0.0, 0.0]));
+
+        $queryVector = new Vector([-1.0, -2.0, -3.0]);
+
+        $result = $calculator->calculate([$doc1, $doc2, $doc3], $queryVector);
+
+        // doc1 should be first (identical to query)
+        $this->assertSame($doc1, $result[0]);
+    }
+
+    #[TestDox('Returns all documents when maxItems exceeds document count')]
+    public function testMaxItemsGreaterThanDocumentCount()
+    {
+        $calculator = new DistanceCalculator();
+
+        $doc1 = new VectorDocument(Uuid::v4(), new Vector([1.0, 0.0]));
+        $doc2 = new VectorDocument(Uuid::v4(), new Vector([0.0, 1.0]));
+
+        $result = $calculator->calculate([$doc1, $doc2], new Vector([1.0, 0.0]), 10);
+
+        // Should return all documents even though maxItems is 10
+        $this->assertCount(2, $result);
+    }
+
+    #[TestDox('Calculates Manhattan distance correctly with mixed positive and negative values')]
+    public function testManhattanDistanceWithMixedSigns()
+    {
+        $calculator = new DistanceCalculator(DistanceStrategy::MANHATTAN_DISTANCE);
+
+        $doc1 = new VectorDocument(Uuid::v4(), new Vector([1.0, -1.0, 2.0]));
+        $doc2 = new VectorDocument(Uuid::v4(), new Vector([-1.0, 1.0, -2.0]));
+        $doc3 = new VectorDocument(Uuid::v4(), new Vector([0.5, -0.5, 1.0]));
+
+        $queryVector = new Vector([0.0, 0.0, 0.0]);
+
+        $result = $calculator->calculate([$doc1, $doc2, $doc3], $queryVector);
+
+        // doc3 has smallest Manhattan distance (2.0), then doc1 and doc2 (both 4.0)
+        $this->assertSame($doc3, $result[0]);
+    }
+
+    #[TestDox('Uses cosine distance as default strategy')]
+    public function testDefaultStrategyIsCosineDistance()
+    {
+        // Test that default constructor uses cosine distance
+        $calculator = new DistanceCalculator();
+
+        // Create vectors where cosine distance ordering differs from Euclidean
+        $doc1 = new VectorDocument(Uuid::v4(), new Vector([1.0, 0.0, 0.0]));
+        $doc2 = new VectorDocument(Uuid::v4(), new Vector([100.0, 0.0, 0.0])); // Same direction but different magnitude
+
+        $queryVector = new Vector([1.0, 0.0, 0.0]);
+
+        $result = $calculator->calculate([$doc1, $doc2], $queryVector);
+
+        // With cosine distance, both should have same distance (parallel vectors)
+        // The order might vary but both are equally similar in terms of direction
+        $this->assertCount(2, $result);
+    }
+}