Propagate error in TFetchResults (#255)

Currently, an error thrown in TFetchResults within getNextPage in
resultPageIterator will be swallowed and an EOF err will be returned
instead. This PR solves #254

Signed-off-by: Vikrant Puppala <vikrant.puppala@databricks.com>

Author: vikrantpuppala

internal/rows/rows.go

@@ -4,7 +4,6 @@ import (
 	"context"
 	"database/sql"
 	"database/sql/driver"
-	"io"
 	"math"
 	"reflect"
 	"time"
@@ -456,10 +455,6 @@ func (r *rows) fetchResultPage() error {
 		r.RowScanner = nil
 	}
 
-	if !r.ResultPageIterator.HasNext() {
-		return io.EOF
-	}
-
 	fetchResult, err1 := r.ResultPageIterator.Next()
 	if err1 != nil {
 		return err1

internal/rows/rows_test.go

@@ -1506,3 +1506,30 @@ func getSimpleClient(fetchResults []cli_service.TFetchResultsResp) cli_service.T
 
 	return client
 }
+
+func getErroringClient(err error) cli_service.TCLIService {
+	fetchResultsFn := func(ctx context.Context, req *cli_service.TFetchResultsReq) (_r *cli_service.TFetchResultsResp, _err error) {
+		return nil, err
+	}
+
+	client := &client.TestClient{
+		FnFetchResults: fetchResultsFn,
+	}
+
+	return client
+}
+
+func TestFetchResultPage_PropagatesGetNextPageError(t *testing.T) {
+	errorMsg := "Error thrown while calling TFetchResults in getNextPage"
+	expectedErr := errors.New(errorMsg)
+
+	client := getErroringClient(expectedErr)
+
+	executeStatementResp := cli_service.TExecuteStatementResp{}
+	cfg := config.WithDefaults()
+	rows, _ := NewRows("connId", "corrId", nil, client, cfg, executeStatementResp.DirectResults)
+	// Call Next and ensure it propagates the error from getNextPage
+	actualErr := rows.Next(nil)
+
+	assert.ErrorContains(t, actualErr, errorMsg)
+}