Add test for #4790: Race condition between StreamRow() and Close()

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Co-Authored-By: Claude <noreply@anthropic.com>

pkg/query/queryresult/result_test.go

@@ -66,6 +66,43 @@ func TestResult_ConcurrentReadAndClose(t *testing.T) {
 	}
 }
 
+func TestResult_ConcurrentStreamRowAndClose(t *testing.T) {
+	// Demonstrates bug #4790 - Race condition between StreamRow() and Close()
+	// When StreamRow() and Close() are called concurrently, we can get a
+	// "send on closed channel" panic if Close() closes the RowChan while
+	// StreamRow() is trying to send to it.
+
+	cols := []*queryresult.ColumnDef{
+		{Name: "id", DataType: "integer"},
+		{Name: "name", DataType: "text"},
+	}
+
+	// Run this test multiple times to increase likelihood of triggering the race
+	for i := 0; i < 100; i++ {
+		result := NewResult(cols)
+
+		// Start a goroutine that sends rows
+		go func() {
+			for j := 0; j < 10; j++ {
+				result.StreamRow([]interface{}{j, "test"})
+			}
+		}()
+
+		// Start a goroutine that consumes rows
+		go func() {
+			for range result.RowChan {
+				// Just drain the channel
+			}
+		}()
+
+		// Close immediately, creating a race with StreamRow
+		result.Close()
+	}
+
+	// If we get here without panicking, the test passes
+	// Run with -race flag to detect the race condition
+}
+
 func TestWrapResult_NilResult(t *testing.T) {
 	// WrapResult should handle nil input gracefully
 	result := WrapResult(nil)