catch2/docs/logging.md

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Logging macros

Additional messages can be logged during a test case.

Streaming macros

All these macros allow heterogenous sequences of values to be streaming using the insertion operator (<<) in the same way that std::ostream, std::cout, etc support it.

E.g.:

INFO( "The number is " << i );

(Note that there is no initial << - instead the insertion sequence is placed in parentheses.) These macros come in three forms:

INFO( message expression )

The message is logged to a buffer, but only reported with the next assertion that is logged. This allows you to log contextual information in case of failures which is not shown during a successful test run (for the console reporter, without -s). Messages are removed from the buffer at the end of their scope, so may be used, for example, in loops.

WARN( message expression )

The message is always reported but does not fail the test.

FAIL( message expression )

The message is reported and the test case fails.

Quickly capture a variable value

CAPTURE( expression )

Sometimes you just want to log the name and value of a variable. While you can easily do this with the INFO macro, above, as a convenience the CAPTURE macro handles the stringising of the variable name for you (actually it works with any expression, not just variables).

E.g.

CAPTURE( theAnswer );

This would log something like:

"theAnswer := 42"

Deprecated macros

SCOPED_INFO and SCOPED_CAPTURE

These macros are now deprecated and are just aliases for INFO and CAPTURE (which were not previously scoped).


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