@Test
public void testPutException() throws IOException {

    ZMSFileChangeLogStoreCommon fstore = new ZMSFileChangeLogStoreCommon(FSTORE_PATH);
    FilesHelper helper = Mockito.mock(FilesHelper.class);
    Mockito.when(helper.write(Mockito.any(), Mockito.any()))
            .thenThrow(new IOException("io exception"));
    fstore.filesHelper = helper;
    Struct data = new Struct();
    data.put("key", "val1");
    try {
        fstore.put("test1", JSON.bytes(data));
        fail();
    } catch (Exception ex) {
        assertTrue(true);
    }
}