[libc] Add 'UNIT_TEST_ONLY' and 'HERMETIC_TEST_ONLY' to 'add_libc_test'

[jhuber6]

Summary

The add_libc_test option allows us to enable both kinds of tests in a
single option. However, some tests cannot be made hermetic with the
current approach. Such as tests that rely on system utilities or
libraries. This patch adds two options UNIT_TEST_ONLY and
HERMETIC_TEST_ONLY to offer more fine-grained control over which
version gets built. This makes it explicit which version a test supports
and why.

Depends on D149662

[sivachandra]

libc/test/src/string/memory_utils/CMakeLists.txt

1–2

Nit: "... to enable a hermetic test also."

18

Nit: Move it right after the test name below line #3.

libc/cmake/modules/LLVMLibCTestRules.cmake

function(add_libc_hermetic_test test_name)
   )
 
   add_dependencies(${HERMETIC_TEST_SUITE} ${fq_target_name})
   add_dependencies(libc-hermetic-tests ${fq_target_name})
 endfunction(add_libc_hermetic_test)
 
 # A convenience function to add both a unit test as well as a hermetic test.
 function(add_libc_test test_name)
-  if(LIBC_ENABLE_UNITTESTS)
-    add_libc_unittest(${test_name}.__unit__ ${ARGN})
+  cmake_parse_arguments(
+    "LIBC_TEST"
+    "UNIT_TEST_ONLY;HERMETIC_TEST_ONLY" # Optional arguments
+    "" # Single value arguments
+    "" # Multi-value arguments
+    ${ARGN}
+  )
+  if(LIBC_ENABLE_UNITTESTS AND NOT LIBC_TEST_HERMETIC_TEST_ONLY)
+    add_libc_unittest(${test_name}.__unit__ ${LIBC_TEST_UNPARSED_ARGUMENTS})
   endif()
-  if(LIBC_ENABLE_HERMETIC_TESTS)
-    add_libc_hermetic_test(${test_name}.__hermetic__ ${ARGN})
+  if(LIBC_ENABLE_HERMETIC_TESTS AND NOT LIBC_TEST_UNIT_TEST_ONLY)
+    add_libc_hermetic_test(${test_name}.__hermetic__ ${LIBC_TEST_UNPARSED_ARGUMENTS})
   endif()
 endfunction(add_libc_test)

libc/test/src/string/memory_utils/CMakeLists.txt

-# This test uses too much memory to be made hermetic.
-add_libc_unittest(
+# This test currently uses too much memory to be made hermetic.
+add_libc_test(
   utils_test
   SUITE
     libc-string-tests
   SRCS
     op_tests.cpp
     utils_test.cpp
   COMPILE_OPTIONS
     ${LIBC_COMPILE_OPTIONS_NATIVE}
     -ffreestanding
   DEPENDS
     libc.src.__support.CPP.array
     libc.src.__support.CPP.cstddef
     libc.src.__support.CPP.span
     libc.src.__support.macros.sanitizer
     libc.src.string.memory_utils.memory_utils
+  UNIT_TEST_ONLY
 )