tests: Google FuzzTest support and chunked container PBT

.bazelrc

@@ -341,4 +341,42 @@ build:io_uring --//bazel:io_uring=True
 test --test_env=REDPANDA_RNG_SEEDING_MODE
 test --test_env=REDPANDA_DEBUG_TEST_HOOKS
 
+# =================================
+# FuzzTest (Google FuzzTest)
+# =================================
+# We define our own config rather than using the generated fuzztest.bazelrc
+# because FuzzTest's coverage runtime (__sanitizer_cov_8bit_counters_init)
+# only tracks a single counter region. The generated config instruments
+# every TU via a global --copt, causing external deps to register their
+# counters first and shadow our code (0 edges covered). Our config applies
+# coverage only to src/v/ via per_file_copt so only Redpanda code is tracked.
+
+# ASan (from fuzztest.bazelrc, duplicated here so we don't need try-import)
+build:fuzztest --linkopt=-fsanitize=address
+build:fuzztest --copt=-fsanitize=address
+build:fuzztest --copt=-DADDRESS_SANITIZER
+
+# Common fuzztest defines
+build:fuzztest --copt=-DFUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
+build:fuzztest --copt=-UNDEBUG
+
+# Link statically
+build:fuzztest --dynamic_mode=off
+
+# Seastar requires system allocator under ASan
+build:fuzztest --@seastar//:system_allocator=True
+build:fuzztest --linkopt=-fsanitize-link-c++-runtime
+
+# Coverage instrumentation ONLY for src/v/ (not global --copt).
+build:fuzztest --per_file_copt=src/v/.*@-fsanitize-coverage=inline-8bit-counters
+build:fuzztest --per_file_copt=src/v/.*@-fsanitize-coverage=trace-cmp
+build:fuzztest --per_file_copt=src/v/.*@-fsanitize-coverage=pc-table
+
+# Suppress warnings from FuzzTest headers included in our source files.
+# Two patterns: one for files with "fuzztest" in the path (including the
+# external fuzztest repo itself), one for *_pbt.cc files which include
+# fuzztest headers but don't have "fuzztest" in their filename.
+build --per_file_copt=.*fuzztest.*@-Wno-nullability-completeness,-Wno-unused-parameter,-Wno-deprecated-declarations,-Wno-sign-compare
+build --per_file_copt=.*_pbt\.cc@-Wno-deprecated-declarations,-Wno-sign-compare,-Wno-unused-parameter,-Wno-nullability-completeness
+
 try-import %workspace%/user.bazelrc

MODULE.bazel

@@ -59,6 +59,7 @@ bazel_dep(name = "zstd", version = "1.5.7")
 bazel_dep(name = "patchelf", version = "0.18.0")
 bazel_dep(name = "bzip2", version = "1.0.8.bcr.2")
 bazel_dep(name = "googleapis", version = "0.0.0-20250703-f9d6fe4a")
+bazel_dep(name = "fuzztest", version = "20260219.0")
 
 bazel_dep(name = "buildifier_prebuilt", version = "8.2.0.2", dev_dependency = True)
 single_version_override(

bazel/test.bzl

@@ -330,6 +330,34 @@ def redpanda_cc_fuzz_test(
         custom_args = args,
     )
 
+def redpanda_cc_fuzztest(
+        name,
+        timeout,
+        srcs = [],
+        defines = [],
+        deps = [],
+        args = [],
+        env = {},
+        cpu = None,
+        memory = None,
+        data = [],
+        tags = []):
+    _redpanda_cc_unit_test(
+        dash_dash_protocol = False,
+        name = name,
+        timeout = timeout,
+        srcs = srcs,
+        defines = defines,
+        cpu = cpu,
+        memory = memory,
+        deps = deps,
+        custom_args = args,
+        env = env,
+        data = data,
+        local_defines = ["IS_GTEST"],
+        tags = tags,
+    )
+
 def redpanda_cc_btest_no_seastar(
         name,
         timeout,

fuzztest.bazelrc

@@ -0,0 +1,85 @@
+### DO NOT EDIT. Generated file.
+#
+# To regenerate, run the following from your project's workspace:
+#
+#  bazel run @com_google_fuzztest//bazel:setup_configs > fuzztest.bazelrc
+#
+# And don't forget to add the following to your project's .bazelrc:
+#
+#  try-import %workspace%/fuzztest.bazelrc
+
+### Common options.
+#
+# Do not use directly.
+
+# Standard define for \"ifdef-ing\" any fuzz test specific code.
+build:fuzztest-common --copt=-DFUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
+
+# In fuzz tests, we want to catch assertion violations even in optimized builds.
+build:fuzztest-common --copt=-UNDEBUG
+
+# Enable libc++ assertions.
+# See https://libcxx.llvm.org/UsingLibcxx.html#enabling-the-safe-libc-mode
+build:fuzztest-common --copt=-D_LIBCPP_ENABLE_ASSERTIONS=1
+
+### ASan (Address Sanitizer) build configuration.
+#
+# Use with: --config=asan
+
+build:asan --linkopt=-fsanitize=address
+build:asan --copt=-fsanitize=address
+
+# We rely on the following flag instead of the compiler provided
+# __has_feature(address_sanitizer) to know that we have an ASAN build even in
+# the uninstrumented runtime.
+build:asan --copt=-DADDRESS_SANITIZER
+
+### FuzzTest build configuration.
+#
+# Use with: --config=fuzztest
+#
+# Note that this configuration includes the ASan configuration.
+
+build:fuzztest --config=asan
+build:fuzztest --config=fuzztest-common
+
+# Link statically.
+build:fuzztest --dynamic_mode=off
+
+# We apply coverage tracking instrumentation to everything but Centipede and the
+# FuzzTest framework itself (including GoogleTest and GoogleMock).
+build:fuzztest --copt=-fsanitize-coverage=inline-8bit-counters,trace-cmp,pc-table
+build:fuzztest --per_file_copt=common/.*,fuzztest/.*,centipede/.*,-centipede/.*fuzz_target,googletest/.*,googlemock/.*@-fsanitize-coverage=0
+
+### Experimental FuzzTest build configuration.
+#
+# Use with: --config=fuzztest-experimental
+#
+# Use this instead of --config=fuzztest when building test binaries to run with
+# Centipede. Eventually, this will be consolidated with --config=fuzztest.
+# Note that this configuration doesn't include the ASan configuration. If you
+# want to use both, you can use --config=fuzztest-experimental --config=asan.
+
+build:fuzztest-experimental --config=fuzztest-common
+build:fuzztest-experimental --@com_google_fuzztest//fuzztest:centipede_integration
+
+# Generate line tables for debugging.
+build:fuzztest-experimental --copt=-gline-tables-only
+build:fuzztest-experimental --strip=never
+
+# Prevent memcmp & co from being inlined.
+build:fuzztest-experimental --copt=-fno-builtin
+
+# Disable heap checking.
+build:fuzztest-experimental --copt=-DHEAPCHECK_DISABLE
+
+# Link statically.
+build:fuzztest-experimental --dynamic_mode=off
+
+# We apply coverage tracking instrumentation to everything but Centipede and the
+# FuzzTest framework itself (including GoogleTest and GoogleMock).
+# TODO(b/374840534): Add -fsanitize-coverage=control-flow once we start building
+# with clang 16+.
+build:fuzztest-experimental --copt=-fsanitize-coverage=trace-pc-guard,pc-table,trace-loads,trace-cmp
+build:fuzztest-experimental --per_file_copt=common/.*,fuzztest/.*,centipede/.*,-centipede/.*fuzz_target,googletest/.*,googlemock/.*@-fsanitize-coverage=0
+

src/v/container/tests/BUILD

@@ -1,4 +1,4 @@
-load("//bazel:test.bzl", "redpanda_cc_bench", "redpanda_cc_btest", "redpanda_cc_gtest", "redpanda_test_cc_library")
+load("//bazel:test.bzl", "redpanda_cc_bench", "redpanda_cc_btest", "redpanda_cc_fuzztest", "redpanda_cc_gtest", "redpanda_test_cc_library")
 
 redpanda_cc_gtest(
     name = "chunked_hash_map_test",
@@ -141,6 +141,21 @@ redpanda_cc_gtest(
     ],
 )
 
+redpanda_cc_fuzztest(
+    name = "chunked_pbt",
+    timeout = "short",
+    srcs = ["chunked_pbt.cc"],
+    cpu = 1,
+    memory = "128MiB",
+    deps = [
+        "//src/v/container:chunked_hash_map",
+        "//src/v/container:chunked_vector",
+        "//src/v/test_utils:fuzztest",
+        "@fuzztest//fuzztest",
+        "@googletest//:gtest",
+    ],
+)
+
 redpanda_cc_bench(
     name = "priority_queue_rpbench",
     srcs = [