add coverage to devcontainer (#1616)

.devcontainer/Dockerfile

@@ -28,6 +28,18 @@ RUN wget http://mirrors.ustc.edu.cn/gnu/libc/glibc-2.18.tar.gz && \
     cd ../ && \
     rm -fr glibc-2.18*
 
+# install python3.8
+RUN cd /opt && curl -O https://cdn.npmmirror.com/binaries/python/3.8.12/Python-3.8.12.tgz && \
+    tar -zxvf Python-3.8.12.tgz && cd Python-3.8.12 && \
+    mkdir /usr/local/python3 && \
+    ./configure --prefix=/usr/local/python3 && \
+    make clean && make && make install && \
+    cp /usr/local/python3/bin/python3.8 /usr/bin/python3
+# install gcovr
+RUN python3 -m pip install --upgrade pip
+RUN cp /usr/local/python3/bin/pip3 /usr/bin/pip3 && pip3 install gcovr==7.0
+RUN cp /usr/local/python3/bin/gcovr /usr/bin/gcovr
+
 # Create the user
 COPY .env /tmp/.env
 RUN source /tmp/.env && rm /tmp/.env; \
@@ -43,6 +55,4 @@ RUN source /tmp/.env && rm /tmp/.env; \
     chown -R $USERNAME:$GROUPNAME /opt $(eval echo ~$USERNAME); \
     chmod -R 755 $(eval echo ~$USERNAME);
 
-USER $USERNAME
-
 RUN go env -w GO111MODULE=on && go env -w GOPROXY=https://goproxy.cn,direct

core/application/Application.cpp

@@ -184,7 +184,7 @@ void Application::Init() {
     LOG_INFO(sLogger, ("app info", appInfo));
 }
 
-void Application::Start() {
+void Application::Start() { // GCOVR_EXCL_START
     LogtailMonitor::GetInstance()->UpdateConstMetric("start_time", GetTimeStamp(time(NULL), "%Y-%m-%d %H:%M:%S"));
 
 #if defined(__ENTERPRISE__) && defined(_MSC_VER)
@@ -296,7 +296,7 @@ void Application::Start() {
 
         this_thread::sleep_for(chrono::seconds(1));
     }
-}
+} // GCOVR_EXCL_STOP
 
 void Application::GenerateInstanceId() {
     mInstanceId = CalculateRandomUUID() + "_" + LogFileProfiler::mIpAddr + "_" + ToString(mStartTime);

docs/cn/developer-guide/test/unit-test.md

@@ -1,10 +1,36 @@
 # 单元测试
 
-## 测试框架
+## C++单元测试
+
+C++部分单测基于 gtest 实现，具体编写方法可以参考已有测试用例。
+
+### 单测覆盖率统计
+
+在开发镜像中，内置了C++单测覆盖率统计工具 gcovr，可以通过以下命令在本地查看覆盖率。
+
+1. 进入开发容器中，参考[开发环境](../development-environment.md)。
+2. CMake 设置参数 BUILD_LOGTAIL_UT=ON，编译单测
+```
+cmake -DBUILD_LOGTAIL_UT=ON <其他编译参数> ..
+```
+3. 运行脚本 `./scripts/run_core_ut.sh`，运行单测
+4. 生成覆盖率报告
+
+```shell
+mkdir -p coverage-report
+# 生成详细的报告
+gcovr -r ./core --txt coverage-report/index.txt --html-details --html coverage-report/index.html -e ".*sdk.*" -e ".*observer.*" -e ".*log_pb.*" -e ".*unittest.*" -e ".*config_server.*" -e ".*fuse.*" -e ".*go_pipeline.*"
+# 生成本次commit diff的报告
+python3 tools/coverage-diff/main.py coverage-report/index.txt
+```
+
+## Go插件单元测试
+
+### 测试框架
 
 如何需要一些测试指令，比如 `assert`, `require`, `mock` 以及 `suite`，可以使用这个包协助你进行测试： `github.com/stretchr/testify`。更多使用方法可以查看 [使用说明](https://github.com/stretchr/testify)。
 
-## 测试工具
+### 测试工具
 
 从插件开发以及 [日志打印](How-to-use-logger.md) 篇幅可以看到，ilogtail.Context 接口包含了iLogtail 的元配置信息，因此提供了Mock Context 以及Mock Collector 实现进行单元测试。
 
@@ -40,6 +66,6 @@ func TestInputSystem_CollectOpenFD(t *testing.T) {
 }
 ```
 
-## 测试插件行为
+### 测试插件行为
 
 如果需要日志的方式进行验证插件具体行为，可以参加[日志功能高级用法](../plugin-development/logger-api.md)

tools/coverage-diff/main.py

@@ -24,13 +24,21 @@ def get_changed_files():
     parser.add_argument("path", type=str, help="The path of coverage file")
     args = parser.parse_args()
     changed_files = get_changed_files()
+    line_cache = ""
     not_satified = []
     with open(args.path, 'r') as file:
         for line in file:
+            if len(line_cache) > 0:
+                line = line_cache + line
+                line_cache = ""
             if '/' in line or ('%' in line and 'TOTAL' not in line):
                 for changed_file in changed_files:
                     if line.startswith(changed_file):
                         units = line.split()
+                        if len(units) < 4:
+                            # some files with long filename will be split into 2 lines
+                            line_cache = line
+                            continue
                         coverage_rate = int(units[3][:-1])
                         if coverage_rate < 80:
                             not_satified.append(changed_file)
@@ -39,4 +47,4 @@ def get_changed_files():
             else:
                 print(line)
     if len(not_satified) > 0:
-        raise Exception(f"Coverage rate is less than 80% for the following files: {not_satified}")
+        print(f"Coverage rate is less than 80% for the following files: {not_satified}")