GoogleTest初探(1)

此篇主要了解一下GoogleTest中的斷言。

總的來說，GoogleTest中的斷言分為兩大類：EXPECT_*和ASSERT_*，這兩者在測試成功或失敗后均會給出測試報告，區別是前者在測試失敗后會繼續執行下面的測試，而后者在測試失敗后會立即終止測試。

 GoogleTest中的比較斷言，涉及整型，字符串， 浮點型，布爾型的比較判斷

Fatal assertion	Nonfatal assertion	Verifies
ASSERT_TRUE(condition)	EXPECT_TRUE(condition)	condition == true
ASSERT_TRUE(condition)	EXPECT_FALSE(condition)	condition == false
ASSERT_EQ(expected, actual)	EXPECT_EQ(expected, actual)	expected == actual
ASSERT_NE(val1, val2)	EXPECT_NE(val1, val2)	val1 != val2
ASSERT_LE(val1, val2)	EXPECT_LE(val1, val2)	val1 <= val2
ASSERT_LT(val1, val2)	EXPECT_LT(val1, val2)	val1 < val2
ASSERT_GE(val1, val2)	EXPECT_GE(val1, val2)	val1 >= val2
ASSERT_GT(val1, val2)	EXPECT_GT(val1, val2)	val1 > val2
ASSERT_STREQ(expected, actual)	EXPECT_STREQ(expected, actual)	(C-string) expected == actual
ASSERT_STRNE(s1, s2)	EXPECT_STRNE(s1, s2)	(C-string) s1 != s2
ASSERT_STRCASEEQ(s1, s2)	EXPECT_STRCASEEQ(s1, s2)	(C-string) s1 == s2  ignoring case
ASSERT_STRCASENE(s1, s2)	EXPECT_STRCASENE(s1, s2)	(C-string) s1 != s2  ignoring case
ASSERT_FLOAT_EQ(expected, actual)	EXPECT_FLOAT_EQ(expected, actual)	(float) expected == actual
ASSERT_DOUBLE_EQ(expected, actual)	EXPECT_DOUBLE_EQ(expected, actual)	(double) expected == actual
ASSERT_NEAR(val1, val2, abs_error)	EXPECT_NEAR(val1, val2, abs_error)	abs(val1-val2) <= abs_error

 

異常斷言：

Fatal assertion	Nonfatal assertion	Verifies
ASSERT_THROW(statement, exception_type);	EXPECT_THROW(statement, exception_type);	statement throws an exception of the given type
ASSERT_ANY_THROW(statement);	EXPECT_ANY_THROW(statement);	statement throws an exception of any type
ASSERT_NO_THROW(statement);	EXPECT_NO_THROW(statement);	statement doesn't throw any exception

 

幾個特殊的斷言（可用於流程控制）

SUCCEED()	一個成功斷言
FAIL()	一個失敗斷言(fatal failure)
ADD_FAILURE()	一個失敗斷言(nonefatal failure)
ADD_FAILURE_AT(file, line)	在給定的文件的給定行數生成一個失敗斷言(nonefatal failure)

 

對於一些待測試的，返回值為bool變量的函數，可以使用以下的斷言（n代表參數個數）：

Fatal assertion	Nonfatal assertion	Verifies
ASSERT_PREDn(predn, val1,...);	EXPECT_PREDn(predn, val1,...);	predn(val1,...) is true

另外，可以對測試函數進行一個包裝，使用以下斷言來判斷包裝好的函數：

Fatal assertion	Nonefatal assertion	Verifies
ASSERT_PRED_FORMATn(pred_formatn, val1, ...);	EXPECT_PRED_FORMATn(pred_formatn, val1, ...);	pred_formatn(val1, ...) is successful

要求pred_formatn的返回值是AssertionResult， 例子如下：

// Returns true if m and n have no common divisors except 1.
bool MutuallyPrime(int m, int n) { ... }

// Returns the smallest prime common divisor of m and n,
// or 1 when m and n are mutually prime.
int SmallestPrimeCommonDivisor(int m, int n) { ... }

// A predicate-formatter for asserting that two integers are mutually prime.
::testing::AssertionResult AssertMutuallyPrime(const char* m_expr,
                                               const char* n_expr,
                                               int m,
                                               int n) 
{
  if (MutuallyPrime(m, n)) return ::testing::AssertionSuccess();

  return ::testing::AssertionFailure() << m_expr << " and " << n_expr
      << " (" << m << " and " << n << ") are not mutually prime, "
      << "as they have a common divisor " << SmallestPrimeCommonDivisor(m, n);
}

使用一個AssertMutuallyPrime函數來包裝一下待測試函數MutuallyPrime。此時再使用斷言：

EXPECT_PRED_FORMAT2(AssertMutuallyPrime, b, c);

如果失敗，則會打印出失敗信息

b and c (4 and 10) are not mutually prime, as they have a common divisor 2.

還有類型斷言：

::testing::StaticAssertTypeEq<T1, T2>();

使用這個函數可以判斷T1和T2類型是否一致

最后，可以使用gmock中的各種matchers來進行斷言：

Fatal assertion	Nonfatal assertion	Verifies
ASSERT_THAT(value, matcher);	EXPECT_THAT(value, matcher);	value matches matcher

matchers 見gmock 的介紹

參考鏈接：https://github.com/google/googletest/blob/master/googletest/docs/advanced.md