libsnapshot_fuzzer: Add tests

Add tests for the fuzzer itself. The test ensures that the
initial corpus is a good run on SnapshotManager (in the sense
that not only it doesn't crash, but also it executes as expected).

Also changed fuzz_utils so that impl functions return the
invocation result too, so that the test can check its values.

Test: run it
Bug: 154633114

Change-Id: I31ab7830f8c20a0575aaadabd038632d10f33962

4 files changed, 248 insertions, 84 deletions

diff --git a/fs_mgr/TEST_MAPPING b/fs_mgr/TEST_MAPPING
index 676f446e72..6cd043013d 100644
--- a/fs_mgr/TEST_MAPPING
+++ b/fs_mgr/TEST_MAPPING
@@ -14,6 +14,9 @@
     },
     {
       "name": "vts_libsnapshot_test"
+    },
+    {
+      "name": "libsnapshot_fuzzer_test"
     }
   ]
 }
diff --git a/fs_mgr/libsnapshot/Android.bp b/fs_mgr/libsnapshot/Android.bp
index c1911022f1..2783e4de4c 100644
--- a/fs_mgr/libsnapshot/Android.bp
+++ b/fs_mgr/libsnapshot/Android.bp
@@ -246,8 +246,8 @@ cc_test {
     gtest: false,
 }
 
-cc_fuzz {
-    name: "libsnapshot_fuzzer",
+cc_defaults {
+    name: "libsnapshot_fuzzer_defaults",
 
     // TODO(b/154633114): make host supported.
     // host_supported: true,
@@ -289,6 +289,11 @@ cc_fuzz {
         canonical_path_from_root: false,
         local_include_dirs: ["."],
     },
+}
+
+cc_fuzz {
+    name: "libsnapshot_fuzzer",
+    defaults: ["libsnapshot_fuzzer_defaults"],
     corpus: ["corpus/*"],
     fuzz_config: {
         cc: ["android-virtual-ab+bugs@google.com"],
@@ -298,3 +303,14 @@ cc_fuzz {
         fuzz_on_haiku_device: true,
     },
 }
+
+cc_test {
+    name: "libsnapshot_fuzzer_test",
+    defaults: ["libsnapshot_fuzzer_defaults"],
+    data: ["corpus/*"],
+    test_suites: [
+        "device-tests",
+    ],
+    auto_gen_config: true,
+    require_root: true,
+}
diff --git a/fs_mgr/libsnapshot/fuzz_utils.h b/fs_mgr/libsnapshot/fuzz_utils.h
index 4dc6cdc0b2..20b13b2fae 100644
--- a/fs_mgr/libsnapshot/fuzz_utils.h
+++ b/fs_mgr/libsnapshot/fuzz_utils.h
@@ -68,17 +68,25 @@ int CheckConsistency() {
     return 0;
 }
 
+// Get the field descriptor for the oneof field in the action message. If no oneof field is set,
+// return nullptr.
 template <typename Action>
-void ExecuteActionProto(typename Action::Class* module,
-                        const typename Action::Proto& action_proto) {
+const google::protobuf::FieldDescriptor* GetValueFieldDescriptor(
+        const typename Action::Proto& action_proto) {
     static auto* action_value_desc = GetProtoValueDescriptor(Action::Proto::GetDescriptor());
 
     auto* action_refl = Action::Proto::GetReflection();
     if (!action_refl->HasOneof(action_proto, action_value_desc)) {
-        return;
+        return nullptr;
     }
+    return action_refl->GetOneofFieldDescriptor(action_proto, action_value_desc);
+}
 
-    const auto* field_desc = action_refl->GetOneofFieldDescriptor(action_proto, action_value_desc);
+template <typename Action>
+void ExecuteActionProto(typename Action::ClassType* module,
+                        const typename Action::Proto& action_proto) {
+    const auto* field_desc = GetValueFieldDescriptor<Action>(action_proto);
+    if (field_desc == nullptr) return;
     auto number = field_desc->number();
     const auto& map = *Action::GetFunctionMap();
     auto it = map.find(number);
@@ -89,7 +97,7 @@ void ExecuteActionProto(typename Action::Class* module,
 
 template <typename Action>
 void ExecuteAllActionProtos(
-        typename Action::Class* module,
+        typename Action::ClassType* module,
         const google::protobuf::RepeatedPtrField<typename Action::Proto>& action_protos) {
     for (const auto& proto : action_protos) {
         ExecuteActionProto<Action>(module, proto);
@@ -134,53 +142,57 @@ FUZZ_DEFINE_PRIMITIVE_GETTER(float, GetFloat);
 // ActionPerformer extracts arguments from the protobuf message, and then call FuzzFunction
 // with these arguments.
 template <typename FuzzFunction, typename Signature, typename Enabled = void>
-struct ActionPerfomer;  // undefined
+struct ActionPerformerImpl;  // undefined
 
 template <typename FuzzFunction, typename MessageProto>
-struct ActionPerfomer<
+struct ActionPerformerImpl<
         FuzzFunction, void(const MessageProto&),
         typename std::enable_if_t<std::is_base_of_v<google::protobuf::Message, MessageProto>>> {
-    static void Invoke(typename FuzzFunction::Class* module,
-                       const google::protobuf::Message& action_proto,
-                       const google::protobuf::FieldDescriptor* field_desc) {
+    static typename FuzzFunction::ReturnType Invoke(
+            typename FuzzFunction::ClassType* module, const google::protobuf::Message& action_proto,
+            const google::protobuf::FieldDescriptor* field_desc) {
         const MessageProto& arg = CheckedCast<std::remove_reference_t<MessageProto>>(
                 action_proto.GetReflection()->GetMessage(action_proto, field_desc));
-        FuzzFunction::ImplBody(module, arg);
+        return FuzzFunction::ImplBody(module, arg);
     }
 };
 
 template <typename FuzzFunction, typename Primitive>
-struct ActionPerfomer<FuzzFunction, void(Primitive),
-                      typename std::enable_if_t<std::is_arithmetic_v<Primitive>>> {
-    static void Invoke(typename FuzzFunction::Class* module,
-                       const google::protobuf::Message& action_proto,
-                       const google::protobuf::FieldDescriptor* field_desc) {
+struct ActionPerformerImpl<FuzzFunction, void(Primitive),
+                           typename std::enable_if_t<std::is_arithmetic_v<Primitive>>> {
+    static typename FuzzFunction::ReturnType Invoke(
+            typename FuzzFunction::ClassType* module, const google::protobuf::Message& action_proto,
+            const google::protobuf::FieldDescriptor* field_desc) {
         Primitive arg = std::invoke(PrimitiveGetter<Primitive>::fp, action_proto.GetReflection(),
                                     action_proto, field_desc);
-        FuzzFunction::ImplBody(module, arg);
+        return FuzzFunction::ImplBody(module, arg);
     }
 };
 
 template <typename FuzzFunction>
-struct ActionPerfomer<FuzzFunction, void()> {
-    static void Invoke(typename FuzzFunction::Class* module, const google::protobuf::Message&,
-                       const google::protobuf::FieldDescriptor*) {
-        FuzzFunction::ImplBody(module);
+struct ActionPerformerImpl<FuzzFunction, void()> {
+    static typename FuzzFunction::ReturnType Invoke(typename FuzzFunction::ClassType* module,
+                                                    const google::protobuf::Message&,
+                                                    const google::protobuf::FieldDescriptor*) {
+        return FuzzFunction::ImplBody(module);
     }
 };
 
 template <typename FuzzFunction>
-struct ActionPerfomer<FuzzFunction, void(const std::string&)> {
-    static void Invoke(typename FuzzFunction::Class* module,
-                       const google::protobuf::Message& action_proto,
-                       const google::protobuf::FieldDescriptor* field_desc) {
+struct ActionPerformerImpl<FuzzFunction, void(const std::string&)> {
+    static typename FuzzFunction::ReturnType Invoke(
+            typename FuzzFunction::ClassType* module, const google::protobuf::Message& action_proto,
+            const google::protobuf::FieldDescriptor* field_desc) {
         std::string scratch;
         const std::string& arg = action_proto.GetReflection()->GetStringReference(
                 action_proto, field_desc, &scratch);
-        FuzzFunction::ImplBody(module, arg);
+        return FuzzFunction::ImplBody(module, arg);
     }
 };
 
+template <typename FuzzFunction>
+struct ActionPerformer : ActionPerformerImpl<FuzzFunction, typename FuzzFunction::Signature> {};
+
 }  // namespace android::fuzz
 
 // Fuzz existing C++ class, ClassType, with a collection of functions under the name Action.
@@ -197,11 +209,11 @@ struct ActionPerfomer<FuzzFunction, void(const std::string&)> {
 //   FUZZ_CLASS(Foo, FooAction)
 // After linking functions of Foo to FooAction, execute all actions by:
 //   FooAction::ExecuteAll(foo_object, action_protos)
-#define FUZZ_CLASS(ClassType, Action)                                                            \
+#define FUZZ_CLASS(Class, Action)                                                                \
     class Action {                                                                               \
       public:                                                                                    \
         using Proto = Action##Proto;                                                             \
-        using Class = ClassType;                                                                 \
+        using ClassType = Class;                                                                 \
         using FunctionMap = android::fuzz::FunctionMap<Class>;                                   \
         static FunctionMap* GetFunctionMap() {                                                   \
             static Action::FunctionMap map;                                                      \
@@ -225,29 +237,33 @@ struct ActionPerfomer<FuzzFunction, void(const std::string&)> {
 // }
 // class Foo { public: void DoAwesomeFoo(bool arg); };
 // FUZZ_OBJECT(FooAction, Foo);
-// FUZZ_FUNCTION(FooAction, DoFoo, module, bool arg) {
+// FUZZ_FUNCTION(FooAction, DoFoo, void, IFoo* module, bool arg) {
 //   module->DoAwesomeFoo(arg);
 // }
 // The name DoFoo is the camel case name of the action in protobuf definition of FooActionProto.
-#define FUZZ_FUNCTION(Action, FunctionName, module, ...)                                         \
-    class FUZZ_FUNCTION_CLASS_NAME(Action, FunctionName) {                                       \
-      public:                                                                                    \
-        using Class = Action::Class;                                                             \
-        static void ImplBody(Action::Class*, ##__VA_ARGS__);                                     \
-                                                                                                 \
-      private:                                                                                   \
-        static bool registered_;                                                                 \
-    };                                                                                           \
-    auto FUZZ_FUNCTION_CLASS_NAME(Action, FunctionName)::registered_ = ([] {                     \
-        auto tag = Action::Proto::ValueCase::FUZZ_FUNCTION_TAG_NAME(FunctionName);               \
-        auto func =                                                                              \
-                &::android::fuzz::ActionPerfomer<FUZZ_FUNCTION_CLASS_NAME(Action, FunctionName), \
-                                                 void(__VA_ARGS__)>::Invoke;                     \
-        Action::GetFunctionMap()->CheckEmplace(tag, func);                                       \
-        return true;                                                                             \
-    })();                                                                                        \
-    void FUZZ_FUNCTION_CLASS_NAME(Action, FunctionName)::ImplBody(Action::Class* module,         \
-                                                                  ##__VA_ARGS__)
+#define FUZZ_FUNCTION(Action, FunctionName, Return, ModuleArg, ...)             \
+    class FUZZ_FUNCTION_CLASS_NAME(Action, FunctionName) {                      \
+      public:                                                                   \
+        using ActionType = Action;                                              \
+        using ClassType = Action::ClassType;                                    \
+        using ReturnType = Return;                                              \
+        using Signature = void(__VA_ARGS__);                                    \
+        static constexpr const char name[] = #FunctionName;                     \
+        static constexpr const auto tag =                                       \
+                Action::Proto::ValueCase::FUZZ_FUNCTION_TAG_NAME(FunctionName); \
+        static ReturnType ImplBody(ModuleArg, ##__VA_ARGS__);                   \
+                                                                                \
+      private:                                                                  \
+        static bool registered_;                                                \
+    };                                                                          \
+    auto FUZZ_FUNCTION_CLASS_NAME(Action, FunctionName)::registered_ = ([] {    \
+        auto tag = FUZZ_FUNCTION_CLASS_NAME(Action, FunctionName)::tag;         \
+        auto func = &::android::fuzz::ActionPerformer<FUZZ_FUNCTION_CLASS_NAME( \
+                Action, FunctionName)>::Invoke;                                 \
+        Action::GetFunctionMap()->CheckEmplace(tag, func);                      \
+        return true;                                                            \
+    })();                                                                       \
+    Return FUZZ_FUNCTION_CLASS_NAME(Action, FunctionName)::ImplBody(ModuleArg, ##__VA_ARGS__)
 
 // Implement a simple action by linking it to the function with the same name. Example:
 // message FooActionProto {
@@ -261,5 +277,9 @@ struct ActionPerfomer<FuzzFunction, void(const std::string&)> {
 // FUZZ_FUNCTION(FooAction, DoBar);
 // The name DoBar is the camel case name of the action in protobuf definition of FooActionProto, and
 // also the name of the function of Foo.
-#define FUZZ_SIMPLE_FUNCTION(Action, FunctionName) \
-    FUZZ_FUNCTION(Action, FunctionName, module) { (void)module->FunctionName(); }
+#define FUZZ_SIMPLE_FUNCTION(Action, FunctionName)                            \
+    FUZZ_FUNCTION(Action, FunctionName,                                       \
+                  decltype(std::declval<Action::ClassType>().FunctionName()), \
+                  Action::ClassType* module) {                                \
+        return module->FunctionName();                                        \
+    }
diff --git a/fs_mgr/libsnapshot/snapshot_fuzz.cpp b/fs_mgr/libsnapshot/snapshot_fuzz.cpp
index 1e90ace6f7..5b145c31f2 100644
--- a/fs_mgr/libsnapshot/snapshot_fuzz.cpp
+++ b/fs_mgr/libsnapshot/snapshot_fuzz.cpp
@@ -21,14 +21,21 @@
 #include <tuple>
 
 #include <android-base/logging.h>
+#include <android-base/properties.h>
+#include <android-base/result.h>
+#include <gtest/gtest.h>
 #include <src/libfuzzer/libfuzzer_macro.h>
 #include <storage_literals/storage_literals.h>
 
 #include "fuzz_utils.h"
 #include "snapshot_fuzz_utils.h"
 
+using android::base::Error;
+using android::base::GetBoolProperty;
 using android::base::LogId;
 using android::base::LogSeverity;
+using android::base::ReadFileToString;
+using android::base::Result;
 using android::base::SetLogger;
 using android::base::StderrLogger;
 using android::base::StdioLogger;
@@ -37,6 +44,8 @@ using android::fuzz::CheckedCast;
 using android::snapshot::SnapshotFuzzData;
 using android::snapshot::SnapshotFuzzEnv;
 using chromeos_update_engine::DeltaArchiveManifest;
+using google::protobuf::FieldDescriptor;
+using google::protobuf::Message;
 using google::protobuf::RepeatedPtrField;
 
 // Avoid linking to libgsi since it needs disk I/O.
@@ -74,48 +83,49 @@ FUZZ_SIMPLE_FUNCTION(SnapshotManagerAction, RecoveryCreateSnapshotDevices);
 FUZZ_SIMPLE_FUNCTION(SnapshotManagerAction, EnsureMetadataMounted);
 FUZZ_SIMPLE_FUNCTION(SnapshotManagerAction, GetSnapshotMergeStatsInstance);
 
-#define SNAPSHOT_FUZZ_FUNCTION(FunctionName, ...) \
-    FUZZ_FUNCTION(SnapshotManagerAction, FunctionName, snapshot, ##__VA_ARGS__)
+#define SNAPSHOT_FUZZ_FUNCTION(FunctionName, ReturnType, ...)                                  \
+    FUZZ_FUNCTION(SnapshotManagerAction, FunctionName, ReturnType, ISnapshotManager* snapshot, \
+                  ##__VA_ARGS__)
 
-SNAPSHOT_FUZZ_FUNCTION(FinishedSnapshotWrites, bool wipe) {
-    (void)snapshot->FinishedSnapshotWrites(wipe);
+SNAPSHOT_FUZZ_FUNCTION(FinishedSnapshotWrites, bool, bool wipe) {
+    return snapshot->FinishedSnapshotWrites(wipe);
 }
 
-SNAPSHOT_FUZZ_FUNCTION(ProcessUpdateState, const ProcessUpdateStateArgs& args) {
+SNAPSHOT_FUZZ_FUNCTION(ProcessUpdateState, bool, const ProcessUpdateStateArgs& args) {
     std::function<bool()> before_cancel;
     if (args.has_before_cancel()) {
         before_cancel = [&]() { return args.fail_before_cancel(); };
     }
-    (void)snapshot->ProcessUpdateState({}, before_cancel);
+    return snapshot->ProcessUpdateState({}, before_cancel);
 }
 
-SNAPSHOT_FUZZ_FUNCTION(GetUpdateState, bool has_progress_arg) {
+SNAPSHOT_FUZZ_FUNCTION(GetUpdateState, UpdateState, bool has_progress_arg) {
     double progress;
-    (void)snapshot->GetUpdateState(has_progress_arg ? &progress : nullptr);
+    return snapshot->GetUpdateState(has_progress_arg ? &progress : nullptr);
 }
 
-SNAPSHOT_FUZZ_FUNCTION(HandleImminentDataWipe, bool has_callback) {
+SNAPSHOT_FUZZ_FUNCTION(HandleImminentDataWipe, bool, bool has_callback) {
     std::function<void()> callback;
     if (has_callback) {
         callback = []() {};
     }
-    (void)snapshot->HandleImminentDataWipe(callback);
+    return snapshot->HandleImminentDataWipe(callback);
 }
 
-SNAPSHOT_FUZZ_FUNCTION(Dump) {
+SNAPSHOT_FUZZ_FUNCTION(Dump, bool) {
     std::stringstream ss;
-    (void)snapshot->Dump(ss);
+    return snapshot->Dump(ss);
 }
 
-SNAPSHOT_FUZZ_FUNCTION(CreateUpdateSnapshots, const DeltaArchiveManifest& manifest) {
-    (void)snapshot->CreateUpdateSnapshots(manifest);
+SNAPSHOT_FUZZ_FUNCTION(CreateUpdateSnapshots, bool, const DeltaArchiveManifest& manifest) {
+    return snapshot->CreateUpdateSnapshots(manifest);
 }
 
-SNAPSHOT_FUZZ_FUNCTION(UnmapUpdateSnapshot, const std::string& name) {
-    (void)snapshot->UnmapUpdateSnapshot(name);
+SNAPSHOT_FUZZ_FUNCTION(UnmapUpdateSnapshot, bool, const std::string& name) {
+    return snapshot->UnmapUpdateSnapshot(name);
 }
 
-SNAPSHOT_FUZZ_FUNCTION(CreateLogicalAndSnapshotPartitions,
+SNAPSHOT_FUZZ_FUNCTION(CreateLogicalAndSnapshotPartitions, bool,
                        const CreateLogicalAndSnapshotPartitionsArgs& args) {
     const std::string* super;
     if (args.use_correct_super()) {
@@ -123,20 +133,21 @@ SNAPSHOT_FUZZ_FUNCTION(CreateLogicalAndSnapshotPartitions,
     } else {
         super = &args.super();
     }
-    (void)snapshot->CreateLogicalAndSnapshotPartitions(
+    return snapshot->CreateLogicalAndSnapshotPartitions(
             *super, std::chrono::milliseconds(args.timeout_millis()));
 }
 
-SNAPSHOT_FUZZ_FUNCTION(RecoveryCreateSnapshotDevicesWithMetadata,
+SNAPSHOT_FUZZ_FUNCTION(RecoveryCreateSnapshotDevicesWithMetadata, CreateResult,
                        const RecoveryCreateSnapshotDevicesArgs& args) {
     std::unique_ptr<AutoDevice> device;
     if (args.has_metadata_device_object()) {
         device = std::make_unique<DummyAutoDevice>(args.metadata_mounted());
     }
-    (void)snapshot->RecoveryCreateSnapshotDevices(device);
+    return snapshot->RecoveryCreateSnapshotDevices(device);
 }
 
-SNAPSHOT_FUZZ_FUNCTION(MapUpdateSnapshot, const CreateLogicalPartitionParamsProto& params_proto) {
+SNAPSHOT_FUZZ_FUNCTION(MapUpdateSnapshot, bool,
+                       const CreateLogicalPartitionParamsProto& params_proto) {
     auto partition_opener = std::make_unique<TestPartitionOpener>(GetSnapshotFuzzEnv()->super());
     CreateLogicalPartitionParams params;
     if (params_proto.use_correct_super()) {
@@ -153,10 +164,10 @@ SNAPSHOT_FUZZ_FUNCTION(MapUpdateSnapshot, const CreateLogicalPartitionParamsProt
     params.device_name = params_proto.device_name();
     params.partition_opener = partition_opener.get();
     std::string path;
-    (void)snapshot->MapUpdateSnapshot(params, &path);
+    return snapshot->MapUpdateSnapshot(params, &path);
 }
 
-SNAPSHOT_FUZZ_FUNCTION(SwitchSlot) {
+SNAPSHOT_FUZZ_FUNCTION(SwitchSlot, void) {
     (void)snapshot;
     CHECK(current_module != nullptr);
     CHECK(current_module->device_info != nullptr);
@@ -194,7 +205,8 @@ void FatalOnlyLogger(LogId logid, LogSeverity severity, const char* tag, const c
 }
 // Stop logging (except fatal messages) after global initialization. This is only done once.
 int StopLoggingAfterGlobalInit() {
-    [[maybe_unused]] static protobuf_mutator::protobuf::LogSilencer log_silincer;
+    (void)GetSnapshotFuzzEnv();
+    [[maybe_unused]] static protobuf_mutator::protobuf::LogSilencer log_silencer;
     SetLogger(&FatalOnlyLogger);
     return 0;
 }
@@ -202,15 +214,10 @@ int StopLoggingAfterGlobalInit() {
 SnapshotFuzzEnv* GetSnapshotFuzzEnv() {
     [[maybe_unused]] static auto allow_logging = AllowLoggingDuringGlobalInit();
     static SnapshotFuzzEnv env;
-    [[maybe_unused]] static auto stop_logging = StopLoggingAfterGlobalInit();
     return &env;
 }
 
-}  // namespace android::snapshot
-
-DEFINE_PROTO_FUZZER(const SnapshotFuzzData& snapshot_fuzz_data) {
-    using namespace android::snapshot;
-
+SnapshotTestModule SetUpTest(const SnapshotFuzzData& snapshot_fuzz_data) {
     current_data = &snapshot_fuzz_data;
 
     auto env = GetSnapshotFuzzEnv();
@@ -219,9 +226,127 @@ DEFINE_PROTO_FUZZER(const SnapshotFuzzData& snapshot_fuzz_data) {
     auto test_module = env->CheckCreateSnapshotManager(snapshot_fuzz_data);
     current_module = &test_module;
     CHECK(test_module.snapshot);
+    return test_module;
+}
 
-    SnapshotManagerAction::ExecuteAll(test_module.snapshot.get(), snapshot_fuzz_data.actions());
-
+void TearDownTest() {
     current_module = nullptr;
     current_data = nullptr;
 }
+
+}  // namespace android::snapshot
+
+DEFINE_PROTO_FUZZER(const SnapshotFuzzData& snapshot_fuzz_data) {
+    using namespace android::snapshot;
+
+    [[maybe_unused]] static auto stop_logging = StopLoggingAfterGlobalInit();
+    auto test_module = SetUpTest(snapshot_fuzz_data);
+    SnapshotManagerAction::ExecuteAll(test_module.snapshot.get(), snapshot_fuzz_data.actions());
+    TearDownTest();
+}
+
+namespace android::snapshot {
+
+// Work-around to cast a 'void' value to Result<void>.
+template <typename T>
+struct GoodResult {
+    template <typename F>
+    static Result<T> Cast(F&& f) {
+        return f();
+    }
+};
+
+template <>
+struct GoodResult<void> {
+    template <typename F>
+    static Result<void> Cast(F&& f) {
+        f();
+        return {};
+    }
+};
+
+class LibsnapshotFuzzerTest : public ::testing::Test {
+  protected:
+    static void SetUpTestCase() {
+        // Do initialization once.
+        (void)GetSnapshotFuzzEnv();
+    }
+    void SetUp() override {
+        bool is_virtual_ab = GetBoolProperty("ro.virtual_ab.enabled", false);
+        if (!is_virtual_ab) GTEST_SKIP() << "Test only runs on Virtual A/B devices.";
+    }
+    void SetUpFuzzData(const std::string& fn) {
+        auto path = android::base::GetExecutableDirectory() + "/corpus/"s + fn;
+        std::string proto_text;
+        ASSERT_TRUE(ReadFileToString(path, &proto_text));
+        snapshot_fuzz_data_ = std::make_unique<SnapshotFuzzData>();
+        ASSERT_TRUE(google::protobuf::TextFormat::ParseFromString(proto_text,
+                                                                  snapshot_fuzz_data_.get()));
+        test_module_ = android::snapshot::SetUpTest(*snapshot_fuzz_data_);
+    }
+    void TearDown() override { android::snapshot::TearDownTest(); }
+    template <typename FuzzFunction>
+    Result<typename FuzzFunction::ReturnType> Execute(int action_index) {
+        if (action_index >= snapshot_fuzz_data_->actions_size()) {
+            return Error() << "Index " << action_index << " is out of bounds ("
+                           << snapshot_fuzz_data_->actions_size() << " actions in corpus";
+        }
+        const auto& action_proto = snapshot_fuzz_data_->actions(action_index);
+        const auto* field_desc =
+                android::fuzz::GetValueFieldDescriptor<typename FuzzFunction::ActionType>(
+                        action_proto);
+        if (field_desc == nullptr) {
+            return Error() << "Action at index " << action_index << " has no value defined.";
+        }
+        if (FuzzFunction::tag != field_desc->number()) {
+            return Error() << "Action at index " << action_index << " is expected to be "
+                           << FuzzFunction::name << ", but it is " << field_desc->name()
+                           << " in corpus.";
+        }
+        return GoodResult<typename FuzzFunction::ReturnType>::Cast([&]() {
+            return android::fuzz::ActionPerformer<FuzzFunction>::Invoke(test_module_.snapshot.get(),
+                                                                        action_proto, field_desc);
+        });
+    }
+
+    std::unique_ptr<SnapshotFuzzData> snapshot_fuzz_data_;
+    SnapshotTestModule test_module_;
+};
+
+#define SNAPSHOT_FUZZ_FN_NAME(name) FUZZ_FUNCTION_CLASS_NAME(SnapshotManagerAction, name)
+
+MATCHER_P(ResultIs, expected, "") {
+    if (!arg.ok()) {
+        *result_listener << arg.error();
+        return false;
+    }
+    *result_listener << "expected: " << expected;
+    return arg.value() == expected;
+}
+
+#define ASSERT_RESULT_TRUE(actual) ASSERT_THAT(actual, ResultIs(true))
+
+// Check that launch_device.txt is executed correctly.
+TEST_F(LibsnapshotFuzzerTest, LaunchDevice) {
+    SetUpFuzzData("launch_device.txt");
+
+    int i = 0;
+    ASSERT_RESULT_TRUE(Execute<SNAPSHOT_FUZZ_FN_NAME(BeginUpdate)>(i++));
+    ASSERT_RESULT_TRUE(Execute<SNAPSHOT_FUZZ_FN_NAME(CreateUpdateSnapshots)>(i++));
+    ASSERT_RESULT_TRUE(Execute<SNAPSHOT_FUZZ_FN_NAME(MapUpdateSnapshot)>(i++)) << "sys_b";
+    ASSERT_RESULT_TRUE(Execute<SNAPSHOT_FUZZ_FN_NAME(MapUpdateSnapshot)>(i++)) << "vnd_b";
+    ASSERT_RESULT_TRUE(Execute<SNAPSHOT_FUZZ_FN_NAME(MapUpdateSnapshot)>(i++)) << "prd_b";
+    ASSERT_RESULT_TRUE(Execute<SNAPSHOT_FUZZ_FN_NAME(FinishedSnapshotWrites)>(i++));
+    ASSERT_RESULT_TRUE(Execute<SNAPSHOT_FUZZ_FN_NAME(UnmapUpdateSnapshot)>(i++)) << "sys_b";
+    ASSERT_RESULT_TRUE(Execute<SNAPSHOT_FUZZ_FN_NAME(UnmapUpdateSnapshot)>(i++)) << "vnd_b";
+    ASSERT_RESULT_TRUE(Execute<SNAPSHOT_FUZZ_FN_NAME(UnmapUpdateSnapshot)>(i++)) << "prd_b";
+    ASSERT_RESULT_OK(Execute<SNAPSHOT_FUZZ_FN_NAME(SwitchSlot)>(i++));
+    ASSERT_EQ("_b", test_module_.device_info->GetSlotSuffix());
+    ASSERT_RESULT_TRUE(Execute<SNAPSHOT_FUZZ_FN_NAME(NeedSnapshotsInFirstStageMount)>(i++));
+    ASSERT_RESULT_TRUE(Execute<SNAPSHOT_FUZZ_FN_NAME(CreateLogicalAndSnapshotPartitions)>(i++));
+    ASSERT_RESULT_TRUE(Execute<SNAPSHOT_FUZZ_FN_NAME(InitiateMerge)>(i++));
+    ASSERT_RESULT_TRUE(Execute<SNAPSHOT_FUZZ_FN_NAME(ProcessUpdateState)>(i++));
+    ASSERT_EQ(i, snapshot_fuzz_data_->actions_size()) << "Not all actions are executed.";
+}
+
+}  // namespace android::snapshot