Add coverage support for fuzzing_regression_test

.bazelrc

@@ -70,3 +70,15 @@ build:asan-jazzer --@rules_fuzzing//fuzzing:cc_engine_instrumentation=jazzer
 build:asan-jazzer --@rules_fuzzing//fuzzing:cc_engine_sanitizer=asan
 # Workaround for https://github.com/bazelbuild/bazel/issues/11128
 build:asan-jazzer --//fuzzing:cc_engine_sanitizer=asan
+
+# Coverage with Replay (C/C++ only)
+coverage --//fuzzing:cc_engine=//fuzzing/engines:replay
+coverage --@rules_fuzzing//fuzzing:cc_engine_instrumentation=none
+coverage --@rules_fuzzing//fuzzing:cc_engine_sanitizer=none
+coverage --instrument_test_targets
+coverage --action_env=BAZEL_USE_LLVM_NATIVE_COVERAGE=1
+coverage --action_env=GCOV=llvm-profdata-10
+coverage --action_env=BAZEL_LLVM_COV=llvm-cov-10
+coverage --combined_report=lcov
+coverage --experimental_use_llvm_covmap
+coverage --experimental_generate_llvm_lcov

.github/workflows/bazel_test.yml

@@ -81,6 +81,28 @@ jobs:
           bazel test --verbose_failures --test_output=all \
               --build_tag_filters=fuzz-test --config=${{ matrix.config }} \
               //examples:all
+  coverage:
+    name: Coverage gathering (C++)
+    runs-on: ubuntu-latest
+    timeout-minutes: 30
+    strategy:
+      matrix:
+        target: ["//examples:empty_fuzz_test", "//examples:re2_fuzz_test"]
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v2
+      - name: Install dependencies
+        run: |
+          sudo apt-get update && sudo apt-get install -yq \
+            clang-10 \
+            libunwind-dev \
+            libblocksruntime-dev
+      - name: Gather coverage
+        run: |
+          bazel coverage ${{ matrix.target }}
+      - name: Check coverage gathered is non-empty
+        run: |
+          [[ -s bazel-out/_coverage/_coverage_report.dat ]]
   fuzzer_run_tests_java:
     name: Brief fuzz test runs (Java)
     runs-on: ubuntu-latest

fuzzing/private/binary.bzl

@@ -131,6 +131,10 @@ def _fuzzing_binary_impl(ctx):
             engine_info = ctx.attr.engine[FuzzingEngineInfo],
             options_file = ctx.file.options,
         ),
+        coverage_common.instrumented_files_info(
+            ctx,
+            dependency_attributes = ["binary"],
+        ),
     ]
 
 _common_fuzzing_binary_attrs = {

fuzzing/private/regression.bzl

@@ -48,7 +48,7 @@ exec '{engine_launcher}'
     runfiles = runfiles.merge(binary_info.engine_info.launcher_runfiles)
     return [DefaultInfo(executable = script, runfiles = runfiles)]
 
-fuzzing_regression_test = rule(
+fuzzing_regression_test_script = rule(
     implementation = _fuzzing_regression_test_impl,
     doc = """
 Executes a fuzz test on its seed corpus.
@@ -62,5 +62,13 @@ Executes a fuzz test on its seed corpus.
             mandatory = True,
         ),
     },
-    test = True,
 )
+
+def fuzzing_regression_test(name, binary, tags):
+    script_name = name + "_regression_test"
+    fuzzing_regression_test_script(name = script_name, binary = binary, tags = tags, testonly = True)
+    native.sh_test(
+        name = name,
+        srcs = [script_name],
+        data = [binary],
+    )