The result of calling stub is that, when where
is invoked and when it internally makes a call to what,
how is going to be called instead.
stub(where, what, how, depth = 1)Function to be called that will in turn call
what.
Name of the function you want to stub out (a
character string).
Replacement function (also a mock function)
or a return value for which a function will be created
automatically.
Specifies the depth to which the function should be stubbed
This is much more limited in scope in comparison to
with_mock which effectively replaces
what everywhere. In other words, when using with_mock
and regardless of the number of intermediate calls, how is
always called instead of what. However, using this API,
the replacement takes place only for a single function where
and only for calls originating in that function.
f <- function() TRUE
g <- function() f()
stub(g, 'f', FALSE)
# now g() returns FALSE because f() has been stubbed out
g()
#> [1] FALSE
# you can stub multiple functions by calling stub() multiple times
f <- function() TRUE
g <- function() TRUE
h <- function() any(f(), g())
stub(h, 'f', FALSE)
stub(h, 'g', FALSE)
# now h() returns FALSE because both f() and g() have been stubbed out
h()
#> [1] FALSE