Fix param validation

collection.go

@@ -279,8 +279,8 @@ func (c *Collection) Query(ctx context.Context, queryText string, nResults int,
 	}
 	c.documentsLock.RLock()
 	defer c.documentsLock.RUnlock()
-	if nResults < len(c.documents) {
-		return nil, errors.New("nResults must be greater than the number of documents in the collection")
+	if nResults > len(c.documents) {
+		return nil, errors.New("nResults must be <= the number of documents in the collection")
 	}
 
 	if len(c.documents) == 0 {

collection_test.go

@@ -308,6 +308,85 @@ func TestCollection_AddConcurrently_Error(t *testing.T) {
 	}
 }
 
+func TestCollection_QueryError(t *testing.T) {
+	// Create collection
+	db := NewDB()
+	name := "test"
+	metadata := map[string]string{"foo": "bar"}
+	vectors := []float32{-0.40824828, 0.40824828, 0.81649655} // normalized version of `{-0.1, 0.1, 0.2}`
+	embeddingFunc := func(_ context.Context, _ string) ([]float32, error) {
+		return vectors, nil
+	}
+	c, err := db.CreateCollection(name, metadata, embeddingFunc)
+	if err != nil {
+		t.Fatal("expected no error, got", err)
+	}
+	if c == nil {
+		t.Fatal("expected collection, got nil")
+	}
+	// Add a document
+	err = c.AddDocument(context.Background(), Document{ID: "1", Content: "hello world"})
+	if err != nil {
+		t.Fatal("expected nil, got", err)
+	}
+
+	tt := []struct {
+		name   string
+		query  func() error
+		expErr string
+	}{
+		{
+			name: "Empty query",
+			query: func() error {
+				_, err := c.Query(context.Background(), "", 1, nil, nil)
+				return err
+			},
+			expErr: "queryText is empty",
+		},
+		{
+			name: "Negative limit",
+			query: func() error {
+				_, err := c.Query(context.Background(), "foo", -1, nil, nil)
+				return err
+			},
+			expErr: "nResults must be > 0",
+		},
+		{
+			name: "Zero limit",
+			query: func() error {
+				_, err := c.Query(context.Background(), "foo", 0, nil, nil)
+				return err
+			},
+			expErr: "nResults must be > 0",
+		},
+		{
+			name: "Limit greater than number of documents",
+			query: func() error {
+				_, err := c.Query(context.Background(), "foo", 2, nil, nil)
+				return err
+			},
+			expErr: "nResults must be <= the number of documents in the collection",
+		},
+		{
+			name: "Bad content filter",
+			query: func() error {
+				_, err := c.Query(context.Background(), "foo", 1, nil, map[string]string{"invalid": "foo"})
+				return err
+			},
+			expErr: "unsupported operator",
+		},
+	}
+
+	for _, tc := range tt {
+		t.Run(tc.name, func(t *testing.T) {
+			err := tc.query()
+			if err.Error() != tc.expErr {
+				t.Fatal("expected", tc.expErr, "got", err)
+			}
+		})
+	}
+}
+
 func TestCollection_Count(t *testing.T) {
 	// Create collection
 	db := NewDB()