test(rccl): add host microtests for src/bootstrap.cc

projects/rccl/test/host/CMakeLists.txt

@@ -388,6 +388,15 @@ function(rccl_define_micro_source_lists)
     fakes/transport_p2p_fakes.cc         # src/transport/p2p.cc shareable buffers
     ../common/main_altrsmi.cpp
     PARENT_SCOPE)
+
+  # rccl-UnitTestsMicroBootstrap -- src/bootstrap.cc. Own binary: the test supplies its own socket layer,
+  # net plugin and logging seams, and other binaries link bootstrap_stubs.cc for this unit's symbols.
+  set(TEST_MICRO_BOOTSTRAP_SOURCE_FILES
+    bootstrap-test.cc
+    fakes/env_fakes.cc
+    fakes/os_fakes.cc
+    ../common/main_altrsmi.cpp
+    PARENT_SCOPE)
 endfunction()
 
 # Create one host-only micro-test binary and apply all the boilerplate that
@@ -1055,6 +1064,16 @@ rccl_add_micro_binary(rccl-UnitTestsMicroClientSupport
     CLIENT_SUPPORT_CC_PATH="${RCCL_HOST_HIPIFY_DIR}/src/ras/client_support.cc"
   CATEGORIES_YAML "${CMAKE_CURRENT_SOURCE_DIR}/../test_categories_micro.yaml")
 
+# ---------------------------------------------------------------------------
+# rccl-UnitTestsMicroBootstrap
+# ---------------------------------------------------------------------------
+rccl_add_micro_binary(rccl-UnitTestsMicroBootstrap
+  SOURCES ${TEST_MICRO_BOOTSTRAP_SOURCE_FILES}
+  EXTRA_DEFS
+    ${_MICRO_MODE_DEFS}
+    BOOTSTRAP_CC_PATH="${RCCL_HOST_HIPIFY_DIR}/src/bootstrap.cc"
+  CATEGORIES_YAML "${CMAKE_CURRENT_SOURCE_DIR}/../test_categories_micro_bootstrap.yaml")
+
 # ---------------------------------------------------------------------------
 # rccl-UnitTestsMicroSymKernels
 # ---------------------------------------------------------------------------

projects/rccl/test/host/MICROTEST_README.md

@@ -310,6 +310,11 @@ export colliding non-`static` symbols; otherwise a unit needs its own binary:
   `NCCL_GIN_PROXY_NTHREADS` progress-thread assignment. Its own binary, not
   sharing `rccl-UnitTestsMicro`: `gin-plugin-init-test.cc` already defines
   `ncclParamGinEnable` there. See `test_categories_micro_gin_host.yaml`.
+- **`rccl-UnitTestsMicroBootstrap`** — `bootstrap.cc` (via `BOOTSTRAP_CC_PATH`, from
+  `bootstrap-test.cc`); suite `Bootstrap*`. Ranks run as threads over an in-memory socket
+  layer and net plugin defined in the test. Its own binary because those seams replace
+  `misc/socket.cc` wholesale, and other binaries link `bootstrap_stubs.cc` for this unit's
+  symbols. See `test_categories_micro_bootstrap.yaml`.
 - **`rccl-UnitTestsMicroDiagnostics`**: `src/diagnostics/p2p.cc` (via
   `DIAG_P2P_CC_PATH`, suite `DiagP2pMicrotest.*`) and `src/diagnostics/ib_write_bw.cc`
   (via `DIAG_IB_WRITE_BW_CC_PATH`, suite `DiagIbWriteBwMicrotest.*`). Its own binary: it fakes the
@@ -829,6 +834,7 @@ can be configured **directly** to build every host binary — `rccl-HostUnitTest
 `rccl-UnitTestsMicro`, `rccl-UnitTestsMicroWarpSpeed`,
 `rccl-UnitTestsMicroInit[-uncached|-faultinj]`, `rccl-UnitTestsMicroEnqueue[-devlinker]`,
 `rccl-UnitTestsMicroGinHost`, `rccl-UnitTestsMicroCe`, `rccl-UnitTestsMicroDiagnostics`,
+`rccl-UnitTestsMicroBootstrap`,
 `rccl-UnitTestsMicroSymKernels` and `rccl-UnitTestsMicroTaskPrep` — **without configuring/building all of
 librccl**. It compiles just the tests + fakes + the hipified unit-under-test
 sources.
@@ -869,6 +875,7 @@ cmake --build build -j"$(nproc)"
 ./build/rccl-UnitTestsMicroTaskPrep           # src/enqueue/task_prep/ + task_sched/ tests
 ./build/rccl-UnitTestsMicroDiagnostics        # src/diagnostics/{p2p,ib_write_bw}.cc tests
 ./build/rccl-UnitTestsMicroGinHost            # src/gin/gin_host.cc GIN_PROXY_NTHREADS
+./build/rccl-UnitTestsMicroBootstrap          # src/bootstrap.cc tests
 ./build/rccl-UnitTestsMicroDiagnostics        # src/diagnostics/p2p.cc tests
 ./build/rccl-UnitTestsMicroCe                 # src/ce_coll.cc tests
 ./build/rccl-HostUnitTests