Additional messages can be logged during a test case (safely even in concurrent threads).
The INFO() macro allows heterogeneous sequences of expressions to be streamed using the insertion operator (<<) in the same way that std::ostream, std::cout, etc support it.
INFO("The number is " << i);
This message will be relevant to all asserts after it in the current scope or in scopes nested in the current one and will be printed later only if an assert fails.
The expression is NOT evaluated right away - instead it gets lazily evaluated only when needed.
Some notes:
The lazy evaluation means that in the common case when no asserts fail the code runs super fast. This makes it suitable even in loops - perhaps to log the iteration.
There is also the CAPTURE() macro which is a convenience wrapper of INFO():
CAPTURE(some_variable)
This will handle the stringification of the variable name for you (actually it works with any expression, not just variables).
This would log something like:
some_variable := 42
There are a few other macros for logging information:
MESSAGE(message)FAIL_CHECK(message)FAIL(message)FAIL() is like a REQUIRE assert - fails the test case and exits it. FAIL_CHECK() acts like a CHECK assert - fails the test case but continues with the execution. MESSAGE() just prints a message.
In all these macros the messages are again composed using the << streaming operator - like this:
FAIL("This is not supposed to happen! some var: " << var);
Also there is no lazy stringification here - strings are always constructed and printed and thus there are no limitations to the values being logged - temporaries and rvalues are accepted - unlike with the INFO() macro.
There are also a few more intended for use by third party libraries such as mocking frameworks:
ADD_MESSAGE_AT(file, line, message)ADD_FAIL_CHECK_AT(file, line, message)ADD_FAIL_AT(file, line, message)They can be useful when integrating asserts from a different framework with doctest.