Fuchsia 支援使用 Fuchsia 偵錯工具 (zxdb) 逐步偵錯元件。偵錯工具會附加至元件執行所在的主機程序，並允許開發人員設定中斷點，逐步完成程式碼執行。開發人員可透過測試執行工具架構編寫可測試驅動程式庫元件的測試。
在本節中，您將使用 Fuchsia 偵錯工具 (zxdb) 檢查執行中的驅動程式庫，並建構測試元件來測試驅動程式庫的功能。
連結偵錯工具
如要將 Fuchsia 偵錯工具連結至驅動程式庫元件，您必須判斷主機程序的 PID。使用 ffx driver list-hosts 指令，找出載入驅動程式庫的主機程序 PID：
ffx driver list-hosts這個指令會輸出類似以下的清單。找出列出 qemu_edu 驅動程式庫的驅動程式代管程序：
Driver Host: 5053
fuchsia-boot:///#meta/block.core.cm
fuchsia-boot:///#meta/bus-pci.cm
fuchsia-boot:///#meta/cpu-trace.cm
fuchsia-boot:///#meta/fvm.cm
fuchsia-boot:///#meta/hid.cm
fuchsia-boot:///#meta/netdevice-migration.cm
fuchsia-boot:///#meta/network-device.cm
fuchsia-boot:///#meta/platform-bus-x86.cm
fuchsia-boot:///#meta/platform-bus.cm
fuchsia-boot:///#meta/ramdisk.cm
fuchsia-boot:///#meta/sysmem.cm
fuchsia-boot:///#meta/virtio_block.cm
fuchsia-boot:///#meta/virtio_ethernet.cm
fuchsia-pkg://fuchsia.com/virtual_audio#meta/virtual_audio_driver.cm
Driver Host: 7774
fuchsia-boot:///#meta/intel-rtc.cm
Driver Host: 7855
fuchsia-boot:///#meta/pc-ps2.cm
Driver Host: 44887
fuchsia-pkg://bazel.pkg.component/qemu_edu#meta/qemu_edu.cm
請記下 qemu_edu 驅動程式代管程序的 PID。在上例中，PID 為 44887。
使用 ffx debug connect 啟動 Fuchsia 偵錯工具：
ffx debug connect偵錯工具連線至目標裝置後，請從 zxdb 提示連結至 qemu_edu 驅動程式庫主機：
[zxdb] attach HOST_PID
將 HOST_PID 替換為上一個步驟中所識別的驅動程式代管程序 PID。例如：
[zxdb] attach 44887
在驅動程式庫的 ComputeFactorial 函式中設定中斷點：
[zxdb] break QemuEduServer::ComputeFactorial
這個指令會輸出類似以下的內容，指出中斷點的設定位置：
[zxdb] break QemuEduServer::ComputeFactorial
Created Breakpoint 1 @ QemuEduServer::ComputeFactorial
47 void QemuEduServer::ComputeFactorial(ComputeFactorialRequestView request,
◉ 48 ComputeFactorialCompleter::Sync& completer) {
49 auto edu_device = device_.lock();
逐步執行驅動程式庫函式
在另一個終端機中，再次執行 eductl 工具：
bazel run //fuchsia-codelab/qemu_edu/tools:pkg.eductl_tool -- fact 12在 zxdb 終端機中，確認偵錯工具已在驅動程式庫的 ComputeFactorial 函式中命中中斷點。例如：
🛑 thread 2 on bp 1 qemu_edu::QemuEduServer::ComputeFactorial(qemu_edu::QemuEduServer*, fidl::WireServer<fuchsia_examples_qemuedu::Device>::ComputeFactorialRequestView, fidl::Completer<fidl::internal::WireCompleterBase<fuchsia_examples_qemuedu::Device::ComputeFactorial> >::Sync&) • qemu_edu.cc:144
46 // Driver Service: Compute factorial on the edu device
47 void QemuEduServer::ComputeFactorial(ComputeFactorialRequestView request,
▶ 48 ComputeFactorialCompleter::Sync& completer) {
49 auto edu_device = device_.lock();
50 if (!edu_device) {
在 zxdb 提示中使用 list 指令，即可顯示目前執行作業的暫停位置：
[zxdb] list
這個指令會輸出類似以下的內容：
46 // Driver Service: Compute factorial on the edu device
47 void QemuEduServer::ComputeFactorial(ComputeFactorialRequestView request,
▶ 48 ComputeFactorialCompleter::Sync& completer) {
49 auto edu_device = device_.lock();
50 if (!edu_device) {
51 FDF_LOG(ERROR, "Unable to access device resources.");
52 completer.ReplyError(ZX_ERR_BAD_STATE);
53 return;
54 }
55
56 uint32_t input = request->input;
57
58 edu_device->ComputeFactorial(input);
使用 next 指令進入 ComputeFactorial 函式：
[zxdb] next
列印傳遞至函式的要求內容：
[zxdb] print request
這個指令會列印包含階乘輸入值的輸出內容：
(*)0x747c1f2e98 ➔ {input = 12}
結束偵錯工具工作階段並中斷連線：
[zxdb] exit
建立新的系統測試元件
在本節中，您將建立新的測試元件，以便測試 qemu_edu 驅動程式庫公開的函式。
在 Bazel 工作區中為新測試元件建立新的專案目錄：
mkdir -p fuchsia-codelab/qemu_edu/tests完成本節後，專案應具有下列目錄結構：
//fuchsia-codelab/qemu_edu/tests
|- BUILD.bazel
|- meta
| |- qemu_edu_system_test.cml
|- qemu_edu_system_test.cc
建立 qemu_edu/tests/BUILD.bazel 檔案，並新增下列陳述式，以納入 Fuchsia SDK 的必要建構規則：
qemu_edu/tests/BUILD.bazel：
load(
"@rules_fuchsia//fuchsia:defs.bzl",
"fuchsia_cc_test",
"fuchsia_component_manifest",
"fuchsia_select",
"fuchsia_test_component",
"fuchsia_test_package",
)
請為專案建立新的 qemu_edu/tests/meta/qemu_edu_system_test.cml 元件資訊清單檔案，並加入下列內容：
qemu_edu/tests/meta/qemu_edu_system_test.cml：
{
include: [
"syslog/client.shard.cml",
"sys/testing/elf_test_runner.shard.cml",
],
program: {
binary: 'bin/qemu_edu_system_test',
},
use: [
{
directory: "dev-topological",
rights: [ "r*" ],
path: "/dev",
},
],
// Required to enable access to devfs
facets: {
"fuchsia.test": { type: "devices" },
},
}
與 eductl 類似，測試元件會使用 dev 目錄能力來探索及存取驅動程式庫。這個元件也包含 elf_test_runner.shard.cml，可讓它使用 Test Runner 架構執行。
建立含有下列內容的新 qemu_edu/tests/qemu_edu_system_test.cc 檔案，以便實作測試：
qemu_edu/tests/qemu_edu_system_test.cc：
#include <dirent.h>
#include <fcntl.h>
#include <fidl/examples.qemuedu/cpp/wire.h>
#include <lib/fdio/directory.h>
#include <sys/types.h>
#include <filesystem>
#include <gtest/gtest.h>
namespace {
constexpr char kDevfsRootPath[] = "/dev/sys/platform/";
constexpr char kEduDevicePath[] = "qemu-edu";
class QemuEduSystemTest : public testing::Test {
public:
void SetUp() {
auto device_path = SearchDevicePath();
ASSERT_TRUE(device_path.has_value());
zx::result endpoints = fidl::CreateEndpoints<examples_qemuedu::Device>();
ASSERT_EQ(endpoints.status_value(), ZX_OK);
ASSERT_EQ(fdio_service_connect(device_path.value().c_str(),
endpoints->server.TakeChannel().release()),
ZX_OK);
device_ = fidl::WireSyncClient(std::move(endpoints->client));
}
// Search for the device file entry in devfs
std::optional<std::string> SearchDevicePath() {
for (auto const& dir_entry : std::filesystem::recursive_directory_iterator(kDevfsRootPath)) {
if (dir_entry.path().string().find(kEduDevicePath) != std::string::npos) {
return {dir_entry.path()};
}
}
return {};
}
fidl::WireSyncClient<examples_qemuedu::Device>& device() { return device_; }
private:
fidl::WireSyncClient<examples_qemuedu::Device> device_;
};
TEST_F(QemuEduSystemTest, LivenessCheck) {
fidl::WireResult result = device()->LivenessCheck();
ASSERT_EQ(result.status(), ZX_OK);
ASSERT_TRUE(result->value()->result);
}
TEST_F(QemuEduSystemTest, ComputeFactorial) {
std::array<uint32_t, 11> kExpected = {
1, 1, 2, 6, 24, 120, 720, 5040, 40320, 362880, 3628800,
};
for (uint32_t i = 0; i < kExpected.size(); i++) {
fidl::WireResult result = device()->ComputeFactorial(i);
ASSERT_EQ(result.status(), ZX_OK);
EXPECT_EQ(result->value()->output, kExpected[i]);
}
}
} // namespace
每個測試案例都會開啟裝置驅動程式庫，並執行其中一個公開函式。
將下列新規則新增至專案的建構設定，將測試元件建構為 Fuchsia 測試套件：
qemu_edu/tests/BUILD.bazel：
fuchsia_cc_test(
name = "qemu_edu_system_test",
size = "small",
srcs = [
"qemu_edu_system_test.cc",
],
deps = ["@com_google_googletest//:gtest_main"] + fuchsia_select({
"@platforms//os:fuchsia": [
"//fuchsia-codelab/qemu_edu/fidl:examples.qemuedu_cc",
"@fuchsia_sdk//pkg/fdio",
],
}),
)
fuchsia_component_manifest(
name = "manifest",
src = "meta/qemu_edu_system_test.cml",
includes = [
"@fuchsia_sdk//pkg/sys/testing:elf_test_runner",
"@fuchsia_sdk//pkg/syslog:client",
],
)
fuchsia_test_component(
name = "component",
manifest = "manifest",
deps = [
":qemu_edu_system_test",
],
)
fuchsia_test_package(
name = "pkg",
package_name = "qemu_edu_system_test",
test_components = [
":component",
],
visibility = ["//visibility:public"],
)
執行系統測試
使用 bazel run 指令建構及執行測試元件目標：
bazel run //fuchsia-codelab/qemu_edu/tests:pkg.componentbazel run 指令會執行下列步驟：
- 建構元件和套件。
- 將套件發布至本機套件存放區。
- 將套件存放區註冊至目標裝置。
- 使用
ffx test run執行元件的測試套件。
驗證所有測試是否成功通過：
Running test 'fuchsia-pkg://bazel.test.pkg.system.test.component/qemu_edu_system_test#meta/qemu_edu_system_test.cm'
[RUNNING] main
[stdout - main]
Running main() from gmock_main.cc
[==========] Running 2 tests from 1 test suite.
[----------] Global test environment set-up.
[----------] 2 tests from QemuEduSystemTest
[ RUN ] QemuEduSystemTest.LivenessCheck
[ OK ] QemuEduSystemTest.LivenessCheck (4 ms)
[ RUN ] QemuEduSystemTest.ComputeFactorial
[ OK ] QemuEduSystemTest.ComputeFactorial (4 ms)
[----------] 2 tests from QemuEduSystemTest (9 ms total)
[----------] Global test environment tear-down
[==========] 2 tests from 1 test suite ran. (9 ms total)
[ PASSED ] 2 tests.
[PASSED] main
後續步驟
恭喜！您已成功對 Fuchsia 驅動程式庫進行偵錯並新增測試。
您現在已瞭解在 Fuchsia 上開發驅動程式的基礎知識，請進一步參閱以下資源，進一步瞭解相關知識：