[sakthivelmanii]

In executeSelect1(), resultSet.next() was called only once for SELECT 1. Closing the ResultSet before consuming the stream to EOF invokes iterator.close(), which sends call.cancel("ResultSet closed", null) to the underlying gRPC stream.

If client cancellation races ahead of the mock server's onCompleted(), the stream terminates with Status.CANCELLED. As a result, SpannerTracer.operationSucceeded() is never invoked, omitting Spanner.ExecuteStreamingSql (status OK) from
spanner.googleapis.com/internal/client/operation_count and causing the test assertion to fail.

Consume the ResultSet to EOF (assertFalse(resultSet.next())) in both BuiltInMetricsCustomOpenTelemetryTest and BuiltInMetricsBothSinksTest to guarantee that the stream finishes normally before closing.

[gemini-code-assist]

Code Review

This pull request adds assertions to verify that the result set has no more elements after reading the first row in Spanner test files. The feedback suggests using Google Truth assertions instead of JUnit assertions in BuiltInMetricsCustomOpenTelemetryTest to maintain consistency with the rest of the codebase.

[gemini-code-assist]

To maintain consistency with the rest of the assertions in this codebase and avoid mixing different assertion frameworks within the same block, please use Google Truth assertions (assertThat(...).isTrue() and assertThat(...).isFalse()) instead of JUnit's assertTrue and assertFalse. If you apply this change, you can also remove the unused import of org.junit.Assert.assertFalse at line 20.

Suggested change

	assertTrue(resultSet.next());
	assertThat(resultSet.getLong(0)).isEqualTo(1L);
	assertFalse(resultSet.next());
	assertThat(resultSet.next()).isTrue();
	assertThat(resultSet.getLong(0)).isEqualTo(1L);
	assertThat(resultSet.next()).isFalse();