@Override
    public int size() {
        return this.jobManagerRunners.size();
    }
@Test
    void size() {
        assertThat(testInstance.size()).isZero();
        testInstance.register(TestingJobManagerRunner.newBuilder().build());
        assertThat(testInstance.size()).isOne();
        testInstance.register(TestingJobManagerRunner.newBuilder().build());
        assertThat(testInstance.size()).isEqualTo(2);
    }