'no module named setuptools' but it is contained in the DEPENDS variable - yocto

Question

This Problem regards Openembedded/Yocto.
I have source code which needs to be compiled by a custom python3 script.
That means, that some python3 script should run during the do_compile() process.
The script imports setuptools, therefore, I added DEPENDS += "python3-setuptools-native" to the recipe. As far as I understand the documentation, this should make the setuptools module available for the building process (native).
But when bitbake executes the do_compile() process, I get this error: no module named 'setuptools'.
Let me break it down to a minimal (non-)working example:
FILE: test.bb
LICENSE = "BSD"
LIC_FILES_CHKSUM = "file://test/LICENSE;md5=d41d8cd98f00b204e9800998ecf8427e"
DEPENDS += "python3-setuptools-native"
SRC_URI = "file://test.py \
file://LICENSE"
do_compile() {
python3 ${S}/../test.py
}
FILE: test.py
import setuptools
print("HELLO")
bitbaking:
$ bitbake test
ERROR: test-1.0-r0 do_compile: Function failed: do_compile (log file is located at /path/to/test/1.0-r0/temp/log.do_compile.8532)
ERROR: Logfile of failure stored in: /path/to/test/1.0-r0/temp/log.do_compile.8532
Log data follows:
| DEBUG: Executing shell function do_compile
| Traceback (most recent call last):
| File "/path/to/test-1.0/../test.py", line 1, in <module>
| import setuptools
| ImportError: No module named 'setuptools'
| WARNING: exit code 1 from a shell command.
| ERROR: Function failed: do_compile (log file is located at /path/to/test/1.0-r0/temp/log.do_compile.8532)
ERROR: Task (/path/to/test.bb:do_compile) failed with exit code '1'
NOTE: Tasks Summary: Attempted 400 tasks of which 398 didn't need to be rerun and 1 failed.
NOTE: Writing buildhistory
Summary: 1 task failed:
/path/to/test.bb:do_compile
Summary: There was 1 ERROR message shown, returning a non-zero exit code.
Is my exepectation wrong, that DEPENDS += "python3-setuptools-native" makes the python3 module 'setuptools' available to the python3 script in do_compile()? How may I accomplish this?

Answer 1

Under the hood quite a bit more is needed to get working setuptools support. Luckily there's a class to handle that:
inherit setuptools3
This should be all that's need to package a setuptools based project with OE-Core. As long as your project has a standard setup.py you don't need to write any do_compile() or do_install() functions.
If you do need to look at the details, meta/classes/setuptools3.bbclass and meta/classes/distutils3.bbclass should contain what you need (including the rather unobvious way to call native python from a recipe).