.Net: Add shared integration tests for checking vector search scores (#10144)

### Motivation and Context

Adds tests for verifying the scores as mentioned in #10103
Only adding tests for passing connectors right now.

### Description

Adding a common base test class with integration tests for checking the
returned vector scores.
Adding subclasses for InMemory, Qdrant and Postgres, since these are
passing end to end.

### Contribution Checklist

<!-- Before submitting this PR, please make sure: -->

- [x] The code builds clean without any errors or warnings
- [x] The PR follows the [SK Contribution
Guidelines](https://github.com/microsoft/semantic-kernel/blob/main/CONTRIBUTING.md)
and the [pre-submission formatting
script](https://github.com/microsoft/semantic-kernel/blob/main/CONTRIBUTING.md#development-scripts)
raises no violations
- [x] All unit tests pass, and I have added new tests where possible
- [x] I didn't break anyone 😄

dotnet/src/IntegrationTests/Connectors/Memory/BaseVectorStoreRecordCollectionTests.cs

@@ -0,0 +1,138 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading.Tasks;
+using Microsoft.Extensions.VectorData;
+using Xunit;
+
+namespace SemanticKernel.IntegrationTests.Connectors.Memory;
+
+/// <summary>
+/// Base class for common integration tests that should pass for any <see cref="IVectorStoreRecordCollection{TKey, TRecord}"/>.
+/// </summary>
+/// <typeparam name="TKey">The type of key to use with the record collection.</typeparam>
+public abstract class BaseVectorStoreRecordCollectionTests<TKey>
+    where TKey : notnull
+{
+    protected abstract TKey Key1 { get; }
+    protected abstract TKey Key2 { get; }
+    protected abstract TKey Key3 { get; }
+    protected abstract TKey Key4 { get; }
+
+    protected abstract HashSet<string> GetSupportedDistanceFunctions();
+
+    protected abstract IVectorStoreRecordCollection<TKey, TRecord> GetTargetRecordCollection<TRecord>(string recordCollectionName, VectorStoreRecordDefinition? vectorStoreRecordDefinition);
+
+    protected virtual int DelayAfterIndexCreateInMilliseconds { get; } = 0;
+
+    protected virtual int DelayAfterUploadInMilliseconds { get; } = 0;
+
+    [Theory]
+    [InlineData(DistanceFunction.CosineDistance, 0, 2, 1, new int[] { 0, 2, 1 })]
+    [InlineData(DistanceFunction.CosineSimilarity, 1, -1, 0, new int[] { 0, 2, 1 })]
+    [InlineData(DistanceFunction.DotProductSimilarity, 1, -1, 0, new int[] { 0, 2, 1 })]
+    [InlineData(DistanceFunction.EuclideanDistance, 0, 2, 1.73, new int[] { 0, 2, 1 })]
+    [InlineData(DistanceFunction.EuclideanSquaredDistance, 0, 4, 3, new int[] { 0, 2, 1 })]
+    [InlineData(DistanceFunction.Hamming, 0, 1, 3, new int[] { 0, 1, 2 })]
+    [InlineData(DistanceFunction.ManhattanDistance, 0, 2, 3, new int[] { 0, 1, 2 })]
+    public async Task VectorSearchShouldReturnExpectedScoresAsync(string distanceFunction, double expectedExactMatchScore, double expectedOppositeScore, double expectedOrthogonalScore, int[] resultOrder)
+    {
+        var keyDictionary = new Dictionary<int, TKey>
+        {
+            { 0, this.Key1 },
+            { 1, this.Key2 },
+            { 2, this.Key3 },
+        };
+        var scoreDictionary = new Dictionary<int, double>
+        {
+            { 0, expectedExactMatchScore },
+            { 1, expectedOppositeScore },
+            { 2, expectedOrthogonalScore },
+        };
+
+        // Don't test unsupported distance functions.
+        var supportedDistanceFunctions = this.GetSupportedDistanceFunctions();
+        if (!supportedDistanceFunctions.Contains(distanceFunction))
+        {
+            return;
+        }
+
+        // Arrange
+        var definition = CreateKeyWithVectorRecordDefinition(4, distanceFunction);
+        var sut = this.GetTargetRecordCollection<KeyWithVectorRecord<TKey>>(
+            $"scorebydistancefunction{distanceFunction}",
+            definition);
+
+        await sut.CreateCollectionIfNotExistsAsync();
+        await Task.Delay(this.DelayAfterIndexCreateInMilliseconds);
+
+        // Create two vectors that are opposite to each other and records that use these
+        // plus a further vector that is orthogonal to the base vector.
+        var baseVector = new ReadOnlyMemory<float>([1, 0, 0, 0]);
+        var oppositeVector = new ReadOnlyMemory<float>([-1, 0, 0, 0]);
+        var orthogonalVector = new ReadOnlyMemory<float>([0f, -1f, -1f, 0f]);
+
+        var baseRecord = new KeyWithVectorRecord<TKey>
+        {
+            Key = this.Key1,
+            Vector = baseVector,
+        };
+
+        var oppositeRecord = new KeyWithVectorRecord<TKey>
+        {
+            Key = this.Key2,
+            Vector = oppositeVector,
+        };
+
+        var orthogonalRecord = new KeyWithVectorRecord<TKey>
+        {
+            Key = this.Key3,
+            Vector = orthogonalVector,
+        };
+
+        await sut.UpsertBatchAsync([baseRecord, oppositeRecord, orthogonalRecord]).ToListAsync();
+        await Task.Delay(this.DelayAfterUploadInMilliseconds);
+
+        // Act
+        var searchResult = await sut.VectorizedSearchAsync(baseVector);
+
+        // Assert
+        var results = await searchResult.Results.ToListAsync();
+        Assert.Equal(3, results.Count);
+
+        Assert.Equal(keyDictionary[resultOrder[0]], results[0].Record.Key);
+        Assert.Equal(Math.Round(scoreDictionary[resultOrder[0]], 2), Math.Round(results[0].Score!.Value, 2));
+
+        Assert.Equal(keyDictionary[resultOrder[1]], results[1].Record.Key);
+        Assert.Equal(Math.Round(scoreDictionary[resultOrder[1]], 2), Math.Round(results[1].Score!.Value, 2));
+
+        Assert.Equal(keyDictionary[resultOrder[2]], results[2].Record.Key);
+        Assert.Equal(Math.Round(scoreDictionary[resultOrder[2]], 2), Math.Round(results[2].Score!.Value, 2));
+
+        // Cleanup
+        await sut.DeleteCollectionAsync();
+    }
+
+    private static VectorStoreRecordDefinition CreateKeyWithVectorRecordDefinition(int vectorDimensions, string distanceFunction)
+    {
+        var definition = new VectorStoreRecordDefinition
+        {
+            Properties =
+            [
+                new VectorStoreRecordKeyProperty("Key", typeof(TKey)),
+                new VectorStoreRecordVectorProperty("Vector", typeof(ReadOnlyMemory<float>)) { Dimensions = vectorDimensions, DistanceFunction = distanceFunction },
+            ],
+        };
+
+        return definition;
+    }
+
+    private sealed class KeyWithVectorRecord<TRecordKey>
+    {
+        public required TRecordKey Key { get; set; }
+
+        public ReadOnlyMemory<float> Vector { get; set; }
+    }
+}

dotnet/src/IntegrationTests/Connectors/Memory/InMemory/CommonInMemoryVectorStoreRecordCollectionTests.cs

@@ -0,0 +1,31 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+using System.Collections.Generic;
+using Microsoft.Extensions.VectorData;
+using Microsoft.SemanticKernel.Connectors.InMemory;
+
+namespace SemanticKernel.IntegrationTests.Connectors.Memory.InMemory;
+
+/// <summary>
+/// Inherits common integration tests that should pass for any <see cref="IVectorStoreRecordCollection{TKey, TRecord}"/>.
+/// </summary>
+public class CommonInMemoryVectorStoreRecordCollectionTests() : BaseVectorStoreRecordCollectionTests<string>
+{
+    protected override string Key1 => "1";
+    protected override string Key2 => "2";
+    protected override string Key3 => "3";
+    protected override string Key4 => "4";
+
+    protected override IVectorStoreRecordCollection<string, TRecord> GetTargetRecordCollection<TRecord>(string recordCollectionName, VectorStoreRecordDefinition? vectorStoreRecordDefinition)
+    {
+        return new InMemoryVectorStoreRecordCollection<string, TRecord>(recordCollectionName, new()
+        {
+            VectorStoreRecordDefinition = vectorStoreRecordDefinition
+        });
+    }
+
+    protected override HashSet<string> GetSupportedDistanceFunctions()
+    {
+        return [DistanceFunction.CosineDistance, DistanceFunction.CosineSimilarity, DistanceFunction.DotProductSimilarity, DistanceFunction.EuclideanDistance];
+    }
+}

dotnet/src/IntegrationTests/Connectors/Memory/Postgres/CommonPostgresVectorStoreRecordCollectionTests.cs

@@ -0,0 +1,34 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+using System.Collections.Generic;
+using Microsoft.Extensions.VectorData;
+using Microsoft.SemanticKernel.Connectors.Postgres;
+using Xunit;
+
+namespace SemanticKernel.IntegrationTests.Connectors.Memory.Postgres;
+
+/// <summary>
+/// Inherits common integration tests that should pass for any <see cref="IVectorStoreRecordCollection{TKey, TRecord}"/>.
+/// </summary>
+/// <param name="fixture">Postres setup and teardown.</param>
+[Collection("PostgresVectorStoreCollection")]
+public class CommonPostgresVectorStoreRecordCollectionTests(PostgresVectorStoreFixture fixture) : BaseVectorStoreRecordCollectionTests<string>
+{
+    protected override string Key1 => "1";
+    protected override string Key2 => "2";
+    protected override string Key3 => "3";
+    protected override string Key4 => "4";
+
+    protected override IVectorStoreRecordCollection<string, TRecord> GetTargetRecordCollection<TRecord>(string recordCollectionName, VectorStoreRecordDefinition? vectorStoreRecordDefinition)
+    {
+        return new PostgresVectorStoreRecordCollection<string, TRecord>(fixture.DataSource!, recordCollectionName, new()
+        {
+            VectorStoreRecordDefinition = vectorStoreRecordDefinition
+        });
+    }
+
+    protected override HashSet<string> GetSupportedDistanceFunctions()
+    {
+        return [DistanceFunction.CosineDistance, DistanceFunction.CosineSimilarity, DistanceFunction.DotProductSimilarity, DistanceFunction.EuclideanDistance, DistanceFunction.ManhattanDistance];
+    }
+}

dotnet/src/IntegrationTests/Connectors/Memory/Postgres/PostgresVectorStoreFixture.cs

@@ -34,7 +34,7 @@ public class PostgresVectorStoreFixture : IAsyncLifetime
     /// <summary>
     /// Holds the Npgsql data source to use for tests.
     /// </summary>
-    private NpgsqlDataSource? _dataSource;
+    public NpgsqlDataSource? DataSource { get; private set; }
 
     private string _connectionString = null!;
     private string _databaseName = null!;
@@ -42,14 +42,14 @@ public class PostgresVectorStoreFixture : IAsyncLifetime
     /// <summary>
     /// Gets a vector store to use for tests.
     /// </summary>
-    public IVectorStore VectorStore => new PostgresVectorStore(this._dataSource!);
+    public IVectorStore VectorStore => new PostgresVectorStore(this.DataSource!);
 
     /// <summary>
     /// Get a database connection
     /// </summary>
     public NpgsqlConnection GetConnection()
     {
-        return this._dataSource!.OpenConnection();
+        return this.DataSource!.OpenConnection();
     }
 
     public IVectorStoreRecordCollection<TKey, TRecord> GetCollection<TKey, TRecord>(
@@ -81,7 +81,7 @@ public class PostgresVectorStoreFixture : IAsyncLifetime
         NpgsqlDataSourceBuilder dataSourceBuilder = new(connectionStringBuilder.ToString());
         dataSourceBuilder.UseVector();
 
-        this._dataSource = dataSourceBuilder.Build();
+        this.DataSource = dataSourceBuilder.Build();
 
         // Wait for the postgres container to be ready and create the test database using the initial data source.
         var initialDataSource = NpgsqlDataSource.Create(this._connectionString);
@@ -124,7 +124,7 @@ public class PostgresVectorStoreFixture : IAsyncLifetime
 
     private async Task CreateTableAsync()
     {
-        NpgsqlConnection connection = await this._dataSource!.OpenConnectionAsync().ConfigureAwait(false);
+        NpgsqlConnection connection = await this.DataSource!.OpenConnectionAsync().ConfigureAwait(false);
 
         await using (connection)
         {
@@ -150,9 +150,9 @@ public class PostgresVectorStoreFixture : IAsyncLifetime
     /// <returns>An async task.</returns>
     public async Task DisposeAsync()
     {
-        if (this._dataSource != null)
+        if (this.DataSource != null)
         {
-            this._dataSource.Dispose();
+            this.DataSource.Dispose();
         }
 
         await this.DropDatabaseAsync();
@@ -218,7 +218,7 @@ public class PostgresVectorStoreFixture : IAsyncLifetime
             await command.ExecuteNonQueryAsync();
         }
 
-        await using (NpgsqlConnection conn = await this._dataSource!.OpenConnectionAsync())
+        await using (NpgsqlConnection conn = await this.DataSource!.OpenConnectionAsync())
         {
             await using (NpgsqlCommand command = new("CREATE EXTENSION vector", conn))
             {

dotnet/src/IntegrationTests/Connectors/Memory/Qdrant/CommonQdrantVectorStoreRecordCollectionTests.cs

@@ -0,0 +1,35 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+using System.Collections.Generic;
+using Microsoft.Extensions.VectorData;
+using Microsoft.SemanticKernel.Connectors.Qdrant;
+using Xunit;
+
+namespace SemanticKernel.IntegrationTests.Connectors.Memory.Qdrant;
+
+/// <summary>
+/// Inherits common integration tests that should pass for any <see cref="IVectorStoreRecordCollection{TKey, TRecord}"/>.
+/// </summary>
+/// <param name="fixture">Qdrant setup and teardown.</param>
+[Collection("QdrantVectorStoreCollection")]
+public class CommonQdrantVectorStoreRecordCollectionTests(QdrantVectorStoreFixture fixture) : BaseVectorStoreRecordCollectionTests<ulong>
+{
+    protected override ulong Key1 => 1;
+    protected override ulong Key2 => 2;
+    protected override ulong Key3 => 3;
+    protected override ulong Key4 => 4;
+
+    protected override IVectorStoreRecordCollection<ulong, TRecord> GetTargetRecordCollection<TRecord>(string recordCollectionName, VectorStoreRecordDefinition? vectorStoreRecordDefinition)
+    {
+        return new QdrantVectorStoreRecordCollection<TRecord>(fixture.QdrantClient, recordCollectionName, new()
+        {
+            HasNamedVectors = true,
+            VectorStoreRecordDefinition = vectorStoreRecordDefinition
+        });
+    }
+
+    protected override HashSet<string> GetSupportedDistanceFunctions()
+    {
+        return [DistanceFunction.CosineSimilarity, DistanceFunction.EuclideanDistance, DistanceFunction.ManhattanDistance];
+    }
+}