差異處
這裏顯示兩個版本的差異處。
Both sides previous revision 前次修改 下次修改 | 前次修改 | ||
java:junit:tech:capture_log4j_output [2018/04/10 14:41] tony |
java:junit:tech:capture_log4j_output [2023/06/25 09:48] (目前版本) |
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行 2: | 行 2: | ||
====== How to verify the Log4j output? ====== | ====== How to verify the Log4j output? ====== | ||
===== Problem ===== | ===== Problem ===== | ||
- | log錯誤是一種錯誤回報的例外處理機制。當功能的測試案例寫完後,就是要開始針對有問題的案例撰寫單元測試。 | + | 當功能的測試案例寫完後,就是要開始針對較特殊的案例撰寫單元測試。log錯誤是一種錯誤回報的例外處理機制,而單元測試中,我們該如何捕捉到這些透過log回報的錯誤呢?\\ |
+ | \\ | ||
+ | Log4j可以透過ConsoleAppender將訊息給顯示到console上,[[java:junit:tech:capture_systemout|先前文章]]也分享過驗證console內容的方法;然而我們不希望使用者看到這些內容,所以預設的log4j設定檔是不使用ConsoleAppender。\\ | ||
+ | \\ | ||
+ | 如果針對測試提供不同的log4j設定檔,也不是那麼的方便,因此我分享給大家另外一種方法,可以將Log4j訊息導到StringBuffer中以做驗證。 | ||
===== How to? ===== | ===== How to? ===== | ||
+ | 主要技巧是透過LogManager在測試之前加入WriterAppender,而WriterAppender會使用我給予的OutputStreamWriter: | ||
<code java> | <code java> | ||
private StringBuffer mSB; | private StringBuffer mSB; | ||
private StringBufferOutputStream mSBOutputStream; | private StringBufferOutputStream mSBOutputStream; | ||
- | private WriterAppender testAppender; | + | private WriterAppender mTestAppender; |
@Before | @Before | ||
行 15: | 行 20: | ||
Writer w = new OutputStreamWriter(mSBOutputStream); | Writer w = new OutputStreamWriter(mSBOutputStream); | ||
- | testAppender = new WriterAppender(); | + | mTestAppender= new WriterAppender(); |
- | testAppender.setLayout(new PatternLayout(PatternLayout.DEFAULT_CONVERSION_PATTERN)); | + | mTestAppender.setLayout(new PatternLayout(PatternLayout.DEFAULT_CONVERSION_PATTERN)); |
- | testAppender.setName("test"); | + | mTestAppender.setName("test"); |
- | testAppender.activateOptions(); | + | mTestAppender.activateOptions(); |
- | testAppender.setWriter(w); | + | mTestAppender.setWriter(w); |
- | LogManager.getLogger(TimeWatcherBuilder.class).addAppender(testAppender); | + | LogManager.getLogger(TimeWatcherBuilder.class).addAppender(mTestAppender); |
} | } | ||
</code> | </code> | ||
+ | 當待測程式碼使用了log4j,就會透過OutputStreamWriter將內容寫入[[java:junit:tech:capture_systemout|StringBufferOutputStream]],而StringBufferOutputStream內部有一個StringBuffer記載內容以供之後驗證。\\ | ||
+ | \\ | ||
+ | 當測試之後,不能忘記移除測試用的Appender: | ||
<code java> | <code java> | ||
@After | @After | ||
public void teardown() throws SchedulerException{ | public void teardown() throws SchedulerException{ | ||
- | LogManager.getLogger(TimeWatcherBuilder.class).removeAppender(testAppender); | + | LogManager.getLogger(TimeWatcherBuilder.class).removeAppender(mTestAppender); |
} | } | ||
</code> | </code> |