Add support for move-only and &&-qualified actions in WillOnce.

This provides a type-safe way for an action to express that it wants to be
called only once, or to capture move-only objects. It is a generalization of
the type system-evading hack in ByMove, with the improvement that it works for
_any_ action (including user-defined ones), and correctly expresses that the
action can only be used with WillOnce. I'll make existing actions benefit in a
future commit.

PiperOrigin-RevId: 440496139
Change-Id: I4145d191cca5655995ef41360bb126c123cb41d3

1 files changed, 3 insertions, 1 deletions

diff --git a/docs/reference/mocking.md b/docs/reference/mocking.md
index c29f716..e414ffb 100644
--- a/docs/reference/mocking.md
+++ b/docs/reference/mocking.md
@@ -248,7 +248,9 @@ EXPECT_CALL(my_mock, GetNumber())
     .WillOnce(Return(3));
 ```
 
-The `WillOnce` clause can be used any number of times on an expectation.
+The `WillOnce` clause can be used any number of times on an expectation. Unlike
+`WillRepeatedly`, the action fed to each `WillOnce` call will be called at most
+once, so may be a move-only type and/or have an `&&`-qualified call operator.
 
 #### WillRepeatedly {#EXPECT_CALL.WillRepeatedly}