Adds a time zone fuzz test (google#326)

Based on
https://github.com/google/oss-fuzz/blob/master/projects/cctz/fuzz_cctz.cc
but uses the Google FuzzTest framework and runs directly in the CCTZ
project using Bazel

Author: derekmauro

.github/workflows/ci.yaml

@@ -19,6 +19,7 @@ jobs:
     - name: Tests
       run: >
         bazel test ...
+        --build_tag_filters=-fuzztest
         --copt=-DGTEST_REMOVE_LEGACY_TEST_CASEAPI_=1
         --copt=-Werror
         --cxxopt=-Wall
@@ -43,7 +44,7 @@ jobs:
         --show_timestamps
         --test_env="TZDIR=${GITHUB_WORKSPACE}/testdata/zoneinfo"
         --test_output=errors
-        --test_tag_filters=-benchmark
+        --test_tag_filters=-benchmark,-fuzztest
 
   Linux-Clang:
     runs-on: ubuntu-latest
@@ -57,6 +58,7 @@ jobs:
       run: >
         bazel test ...
         --action_env=CC=clang
+        --build_tag_filters=-fuzztest
         --copt=-DGTEST_REMOVE_LEGACY_TEST_CASEAPI_=1
         --copt=-Werror
         --cxxopt=-Wall
@@ -97,7 +99,33 @@ jobs:
         --show_timestamps
         --test_env="TZDIR=${GITHUB_WORKSPACE}/testdata/zoneinfo"
         --test_output=errors
-        --test_tag_filters=-benchmark
+        --test_tag_filters=-benchmark,-fuzztest
+
+  Linux-FuzzTest:
+    runs-on: ubuntu-latest
+    steps:
+
+    - uses: actions/checkout@v4
+      with:
+        fetch-depth: 0
+
+    - name: Configure Fuzztest
+      run: bazel run @fuzztest//bazel:setup_configs > fuzztest.bazelrc
+    - name: Fuzz
+      run: >
+        bazel --bazelrc=fuzztest.bazelrc test ...
+        --action_env=CC=clang
+        --build_tag_filters=fuzztest
+        --config=fuzztest
+        --copt=-DGTEST_REMOVE_LEGACY_TEST_CASEAPI_=1
+        --define=absl=1
+        --features=external_include_paths
+        --keep_going
+        --show_timestamps
+        --test_arg=--fuzz_for=30s
+        --test_env="TZDIR=${GITHUB_WORKSPACE}/testdata/zoneinfo"
+        --test_output=errors
+        --test_tag_filters=fuzztest
 
   macOS:
     runs-on: macos-latest
@@ -110,13 +138,14 @@ jobs:
     - name: Tests
       run: >
         bazel test ...
+        --build_tag_filters=-fuzztest
         --cxxopt="-std=c++17"
         --features=external_include_paths
         --keep_going
         --show_timestamps
         --test_env="TZDIR=${GITHUB_WORKSPACE}/testdata/zoneinfo"
         --test_output=errors
-        --test_tag_filters=-benchmark
+        --test_tag_filters=-benchmark,-fuzztest
 
   Windows:
     runs-on: windows-latest
@@ -129,8 +158,9 @@ jobs:
     - name: Tests
       run: >
         bazel test ...
+        --build_tag_filters="-fuzztest"
         --keep_going
         --show_timestamps
         --test_env="TZDIR=$env:GITHUB_WORKSPACE\testdata\zoneinfo"
         --test_output=errors
-        --test_tag_filters=-benchmark
+        --test_tag_filters="-benchmark,-fuzztest"

BUILD

@@ -75,9 +75,12 @@ cc_library(
 
 ### tests
 
-test_suite(
-    name = "all_tests",
-    visibility = ["//visibility:public"],
+cc_library(
+    name = "test_time_zone_names",
+    testonly = True,
+    srcs = ["src/test_time_zone_names.cc"],
+    hdrs = ["src/test_time_zone_names.h"],
+    visibility = ["//visibility:private"],
 )
 
 cc_test(
@@ -109,12 +112,35 @@ cc_test(
     srcs = ["src/time_zone_lookup_test.cc"],
     deps = [
         ":civil_time",
+        ":test_time_zone_names",
         ":time_zone",
         "@googletest//:gtest",
         "@googletest//:gtest_main",
     ],
 )
 
+cc_test(
+    name = "time_zone_fuzz_test",
+    srcs = [
+        "src/time_zone_fuzz_test.cc",
+        "src/time_zone_if.h",
+        "src/time_zone_impl.h",
+        "src/time_zone_info.h",
+        "src/tzfile.h",
+    ],
+    tags = [
+        "fuzztest",
+    ],
+    deps = [
+        ":civil_time",
+        ":test_time_zone_names",
+        ":time_zone",
+        "@fuzztest//fuzztest",
+        "@fuzztest//fuzztest:fuzztest_gtest_main",
+        "@googletest//:gtest",
+    ],
+)
+
 ### benchmarks
 
 cc_test(
@@ -130,6 +156,7 @@ cc_test(
     tags = ["benchmark"],
     deps = [
         ":civil_time",
+        ":test_time_zone_names",
         ":time_zone",
         "@google_benchmark//:benchmark_main",
     ],

CMakeLists.txt

@@ -111,6 +111,11 @@ if (BUILD_EXAMPLES)
 endif()
 
 if (BUILD_TESTING)
+  add_library(test_time_zone_names
+    "src/test_time_zone_names.cc"
+    "src/test_time_zone_names.h"
+    )
+
   add_executable(civil_time_test src/civil_time_test.cc)
   cctz_target_set_cxx_standard(civil_time_test)
   target_include_directories(civil_time_test PRIVATE ${GTEST_INCLUDE_DIRS})
@@ -126,6 +131,7 @@ if (BUILD_TESTING)
   target_include_directories(time_zone_lookup_test PRIVATE ${GTEST_INCLUDE_DIRS})
   target_link_libraries(time_zone_lookup_test
     cctz::cctz
+    test_time_zone_names
     ${GTEST_BOTH_LIBRARIES}
     ${CMAKE_THREAD_LIBS_INIT}
     )
@@ -153,7 +159,11 @@ if (BUILD_TESTING)
   if (BUILD_BENCHMARK)
     add_executable(cctz_benchmark src/cctz_benchmark.cc)
     cctz_target_set_cxx_standard(cctz_benchmark)
-    target_link_libraries(cctz_benchmark cctz::cctz benchmark::benchmark_main)
+    target_link_libraries(cctz_benchmark
+      cctz::cctz
+      test_time_zone_names
+      benchmark::benchmark_main
+      )
   endif()
 endif()
 

MODULE.bazel

@@ -22,6 +22,10 @@ module(
 
 # Only direct dependencies need to be listed below.
 
+bazel_dep(name = "fuzztest",
+          version = "20250728.0",
+          dev_dependency = True)
+
 bazel_dep(name = "google_benchmark",
           version = "1.9.4",
           dev_dependency = True)