Catch/docs/logging.md

# 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.:
```c++
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).

**SCOPED_INFO(** _message expression_ **)**

As INFO, but is only in effect during the current scope. If a failure occurs beyond the end of the scope the message is not logged. In a looped block the message is reset on each iteration.

**WARN(** _message expression_ **)**

The message is always reported.

**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.
```c++
CAPTURE( theAnswer );
```

This would log something like:

<pre>"theAnswer := 42"</pre>

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