Is it possible to share header file only with a cc_test target?

Question

Say I have a package with a single cc_library target and an inner package for tests with a single cc_test target as follows:

mylib/
     BUILD
     mylib.h
     mylib.c
     mylib-private.h
     tests/
         BUILD
         test.c

In order to perform some unit-tests I need access to "private" methods, so I created mylib-private.h which I want to include only in the test code.
Obviously this header should not be part of the library API and should not be shipped with it.

If I add mylib-private to the hdrs of mylib - It'll be visible to all.
If I add mylib-private to srcs of mylib - only mylib can use it...

Is there a way to control the visibility of a single header file?

Answer 1

Not sure what is the official recommended pattern here, but I ended up inclduing both mylib and mylib-tests in the same package, and then they could both add mylib-private to their srcs attribute:

BUILD:

cc_library(
    name="mylib",
    hdrs=["mylib.h",],
    srcs=[
        "mylib.c",
        "mylib-private.h"
    ]
)

cc_test(
    name="mylib-tests",
    srcs=glob([
        "tests/*.c",
        "mylib-private.h"
    ]),
    deps=[
        "//:mylib"
    ]
)

And the structure:

mylib/
     BUILD
     mylib.h
     mylib.c
     mylib-private.h
     tests/
         test.c