[SOLVED] gtest: check if string is equal to one of two strings

gtest: check if string is equal to one of two strings

Consider that I have two strings:

std::string s1 = "ab"; 
std::string s2 = "cd";

and I want to check (e.g. using EXPECT_EQ) if some given std::string str is equal either to s1 or s2.

If gtest's ASSERT_* and EXPECT_* would return bool I could have written

EXPECT_TRUE(EXPECT_EQ(str, s1) || EXPECT_EQ(str, s2));

but, unfortunately, they don't.

Solution

There is one problem with EXPECT_TRUE in this case. In gtest's doc it is described as:

sometimes a user has to use EXPECT_TRUE() to check a complex expression, for lack of a better macro. This has the problem of not showing you the values of the parts of the expression, making it hard to understand what went wrong.

So it is suggested to use EXPECT_PRED:

TEST(CompareStr, Test1) {
  std::string s1 = "ab";
  std::string s2 = "cd";
  std::string str;
  EXPECT_PRED3([](auto str, auto s1, auto s2) {
    return str == s1 || str == s2;}, str, s1, s2);
}

It gives a bit better diagnostic if a unittest fails:

[ RUN      ] CompareStr.Test1
Test.cpp:5: Failure
[](auto str, auto s1, auto s2) { return str == s1 || str == s2;}(str, s1, s2) evaluates to false, where
str evaluates to 
s1 evaluates to ab
s2 evaluates to cd

You can compare the message above with the output from EXPECT_TRUE:

Value of: s1 == str || s2 == str
  Actual: false
Expected: true