junit.framework包下的Assert提供了多個斷言方法. 主用于比較測試傳遞進去的兩個參數.

Assert.assertEquals();及其重載方法: 1. 如果兩者一致, 程序繼續往下運行. 2. 如果兩者不一致, 中斷測試方法, 拋出異常信息 AssertionFailedError .

查看源碼, 以Assert.assertEquals(int expected, int actual)為例:

/** * Asserts that two ints are equal. 斷言兩個int是相等的 */static public void assertEquals(int expected, int actual) { assertEquals(null, expected, actual);}

可以看到里面調用了assertEquals(String message, int expected, int actual)方法:

/** * Asserts that two ints are equal. If they are not * an AssertionFailedError is thrown with the given message. * 如果不拋出帶有 message 的異常(AssertionFailedError)信息, 則表明兩者相等 */static public void assertEquals(String message, int expected, int actual) { assertEquals(message, Integer.valueOf(expected), Integer.valueOf(actual));}

可以看到, 這里把int類型封箱成為Integer類型. 注釋說, 會拋異常, 但這里沒有. 沒關系, 我們接著看里面調用: assertEquals(String message, Object expected, Object actual)方法:

/** * Asserts that two objects are equal. If they are not * an AssertionFailedError is thrown with the given message. * 如果不拋出帶有 message 的異常(AssertionFailedError)信息, 則表明兩者相等(這里比較的是Object對象) */static public void assertEquals(String message, Object expected, Object actual) { if (expected == null && actual == null) {return; } if (expected != null && expected.equals(actual)) {return; } failNotEquals(message, expected, actual);}

兩個if語句, 判斷了兩者相等的情況: 引用(地址)相等或者內容相等. 如果這兩種if情況都不命中, 那么表明1參和2參實際是不相等, 所以代碼會往下執行failNotEquals(String message, Object expected, Object actual)方法，并在此方法中拋出異常, 接下來就比較簡單了:

static public void failNotEquals(String message, Object expected, Object actual) { fail(format(message, expected, actual));}public static String format(String message, Object expected, Object actual) { String formatted = ''; if (message != null && message.length() > 0) {formatted = message + ' '; } return formatted + 'expected:<' + expected + '> but was:<' + actual + '>';}/*** Fails a test with the given message.*/static public void fail(String message) {if (message == null) { throw new AssertionFailedError();}throw new AssertionFailedError(message);}

以上可以看出, 最終是由fail(String message)這個方法拋出異常信息!!

Assert.assertEquals()使用方法:使用, 示例代碼:

Assert.assertEquals(true, arry.contains('hello'));Assert.assertEquals(39991L, aa.getLong('key3', 0L));Assert.assertEquals(true, bb.getBoolean('key4', false));Assert.assertEquals(5.3f, cc.getFloat('key5', 0.f));Assert.assertEquals(99, dd.getInt('key6', 1));Assert.assertEquals('如果打印本信息, 證明參數不相等', 10L, 10);

按照源碼分析, 我們可以把一個預期結果作為1參傳遞進去. 2參傳遞我們需要測試的方法. 然后執行. 相等, 代碼繼續往下執行, 不相等, 中斷執行, 拋出異常信息!!!

略作一提:Assert.assertSame(Object expected, Object actual)方法:查看源碼, 其比較的是引用地址是否相等, 并沒有對內容進行比較:

/** * Asserts that two objects refer to the same object. If they are not * the same an AssertionFailedError is thrown. */static public void assertSame(Object expected, Object actual) { assertSame(null, expected, actual);}/** * Asserts that two objects refer to the same object. If they are not * an AssertionFailedError is thrown with the given message. */static public void assertSame(String message, Object expected, Object actual) { if (expected == actual) {return; } failNotSame(message, expected, actual);}

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