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bash的自动化测试框架-bats

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今天在kubernetes中部署mongodb-rs时，发现其helm模板中使用到了一个bats,搜索了一下发现这是一个对bash领域的自动化测试框架，简单学习一下.

使用

mongodb-rs的部署不在这里详述了，直接来到使用到bats的地方,

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---
# Source: mongodb-replicaset/templates/tests/mongodb-up-test-pod.yaml
apiVersion: v1
kind: Pod
metadata:
  labels:
    app: mongodb-replicaset
    chart: mongodb-replicaset-3.17.0
    heritage: Helm
    release: mongodb-rs
  name: mongodb-rs-mongodb-replicaset-test
  namespace: infra
  annotations:
    "helm.sh/hook": test-success
spec:
  initContainers:
    - name: test-framework
      image: dduportal/bats:0.4.0
      command:
        - bash
        - -c
        - |
          set -ex
          # copy bats to tools dir
          cp -R /usr/local/libexec/ /tools/bats/
      volumeMounts:
        - name: tools
          mountPath: /tools
  containers:
    - name: mongo
      image: "mongo:4.2"
      command:
        - /tools/bats/bats
        - -t
        - /tests/mongodb-up-test.sh
      env:
        - name: FULL_NAME
          value: mongodb-rs-mongodb-replicaset
        - name: NAMESPACE
          value: infra
        - name: REPLICAS
          value: "3"
        - name: AUTH
          value: "true"
        - name: ADMIN_USER
          valueFrom:
            secretKeyRef:
              name: "mongodb-rs-mongodb-replicaset-admin"
              key: user
        - name: ADMIN_PASSWORD
          valueFrom:
            secretKeyRef:
              name: "mongodb-rs-mongodb-replicaset-admin"
              key: password
      volumeMounts:
        - name: tools
          mountPath: /tools
        - name: tests
          mountPath: /tests
  volumes:
    - name: tools
      emptyDir: {}
    - name: tests
      configMap:
        name: mongodb-rs-mongodb-replicaset-tests
  restartPolicy: Never # 指定pod的启动命令为Never，表示只运行一次.

首先看到initContainers执行了cp -R /usr/local/libexec/ /tools/bats/，从bats github中可以看到，这个目录下是一些可执行的bash代码，这是整个核心.

然后在主containers中执行了/tools/bats/bats -t /tests/mongodb-up-test.sh, 这个脚本内容如下:

cat mongodb-up-test.sh

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#!/usr/bin/env bash
    
    set -ex
    
    CACRT_FILE=/work-dir/tls.crt
    CAKEY_FILE=/work-dir/tls.key
    MONGOPEM=/work-dir/mongo.pem
    
    MONGOARGS="--quiet"
    
    if [ -e "/tls/tls.crt" ]; then
        # log "Generating certificate"
        mkdir -p /work-dir
        cp /tls/tls.crt /work-dir/tls.crt
        cp /tls/tls.key /work-dir/tls.key
    
        # Move into /work-dir
        pushd /work-dir
    
    cat >openssl.cnf <<EOL
    [req]
    req_extensions = v3_req
    distinguished_name = req_distinguished_name
    [req_distinguished_name]
    [ v3_req ]
    basicConstraints = CA:FALSE
    keyUsage = nonRepudiation, digitalSignature, keyEncipherment
    subjectAltName = @alt_names
    [alt_names]
    DNS.1 = $(echo -n "$(hostname)" | sed s/-[0-9]*$//)
    DNS.2 = $(hostname)
    DNS.3 = localhost
    DNS.4 = 127.0.0.1
    EOL
    
        # Generate the certs
        openssl genrsa -out mongo.key 2048
        openssl req -new -key mongo.key -out mongo.csr -subj "/OU=MongoDB/CN=$(hostname)" -config openssl.cnf
        openssl x509 -req -in mongo.csr \
            -CA "$CACRT_FILE" -CAkey "$CAKEY_FILE" -CAcreateserial \
            -out mongo.crt -days 3650 -extensions v3_req -extfile openssl.cnf
        cat mongo.crt mongo.key > $MONGOPEM
        MONGOARGS="$MONGOARGS --ssl --sslCAFile $CACRT_FILE --sslPEMKeyFile $MONGOPEM"
    fi
    
    if [[ "${AUTH}" == "true" ]]; then
        MONGOARGS="$MONGOARGS --username $ADMIN_USER --password $ADMIN_PASSWORD --authenticationDatabase admin"
    fi
    
    pod_name() {
        local full_name="${FULL_NAME?Environment variable FULL_NAME not set}"
        local namespace="${NAMESPACE?Environment variable NAMESPACE not set}"
        local index="$1"
        echo "$full_name-$index.$full_name.$namespace.svc.cluster.local"
    }
    
    replicas() {
        echo "${REPLICAS?Environment variable REPLICAS not set}"
    }
    
    master_pod() {
        for ((i = 0; i < $(replicas); ++i)); do
            response=$(mongo $MONGOARGS "--host=$(pod_name "$i")" "--eval=rs.isMaster().ismaster")
            if [[ "$response" == "true" ]]; then
                pod_name "$i"
                break
            fi
        done
    }
    
    setup() {
        local ready=0
        until [[ "$ready" -eq $(replicas) ]]; do
            echo "Waiting for application to become ready" >&2
            sleep 1
            ready=0
            for ((i = 0; i < $(replicas); ++i)); do
                response=$(mongo $MONGOARGS "--host=$(pod_name "$i")" "--eval=rs.status().ok" || true)
                if [[ "$response" -eq 1 ]]; then
                    ready=$((ready + 1))
                fi
            done
        done
    }
    
    @test "Testing mongodb client is executable" {
        mongo -h
        [ "$?" -eq 0 ]
    }
    
    @test "Connect mongodb client to mongodb pods" {
        for ((i = 0; i < $(replicas); ++i)); do
            response=$(mongo $MONGOARGS "--host=$(pod_name "$i")" "--eval=rs.status().ok")
            if [[ ! "$response" -eq 1 ]]; then
                exit 1
            fi
        done
    }
    
    @test "Write key to primary" {
        response=$(mongo $MONGOARGS --host=$(master_pod) "--eval=db.test.insert({\"abc\": \"def\"}).nInserted")
        if [[ ! "$response" -eq 1 ]]; then
            exit 1
        fi
    }
    
    @test "Read key from slaves" {
        # wait for slaves to catch up
        sleep 10
    
        for ((i = 0; i < $(replicas); ++i)); do
            response=$(mongo $MONGOARGS --host=$(pod_name "$i") "--eval=rs.slaveOk(); db.test.find({\"abc\":\"def\"})")
            if [[ ! "$response" =~ .*def.* ]]; then
                exit 1
            fi
        done
    
        # Clean up a document after test
        mongo $MONGOARGS --host=$(master_pod) "--eval=db.test.deleteMany({\"abc\": \"def\"})"
    }

该脚本的上半部分可以先忽略

然后定义了几个函数, 其实setup()函数在bats中是特殊的函数,其实还有一个teardown，主要用于在执行测试函数前/后执行的两个函数， setup用于做一些准备工作,teardown用于做一些清理工作

最重要的部分是@test,比如:

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@test "Testing mongodb client is executable" {
    mongo -h
    [ "$?" -eq 0 ]
}

@test是一个关键字，指定被包含代码块需要被testing.在上面的脚本中指定了4个@test函数. 它到底是如何执行的呢？

源码分析

首先: 在bats-preprocess中,这个代码主要是解析待测试脚本，可以发现以下代码:

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pattern='^ *@test  *([^ ].*)  *\{ *(.*)$'

while IFS= read -r line; do
  let index+=1
  if [[ "$line" =~ $pattern ]]; then
    quoted_name="${BASH_REMATCH[1]}"
    body="${BASH_REMATCH[2]}"
    name="$(eval echo "$quoted_name")"
    encoded_name="$(encode_name "$name")"
    tests["${#tests[@]}"]="$encoded_name"
    echo "${encoded_name}() { bats_test_begin ${quoted_name} ${index}; ${body}"
  else
    printf "%s\n" "$line"
  fi
done

通过解析@test来得到有多个需要testing的代码块，从pod的日志中也可以看出

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++ bats_test_function test_Testing_mongodb_client_is_executable
++ local test_name=test_Testing_mongodb_client_is_executable
++ BATS_TEST_NAMES["${#BATS_TEST_NAMES[@]}"]=test_Testing_mongodb_client_is_executable
++ bats_test_function test_Connect_mongodb_client_to_mongodb_pods
++ local test_name=test_Connect_mongodb_client_to_mongodb_pods
++ BATS_TEST_NAMES["${#BATS_TEST_NAMES[@]}"]=test_Connect_mongodb_client_to_mongodb_pods
++ bats_test_function test_Write_key_to_primary
++ local test_name=test_Write_key_to_primary
++ BATS_TEST_NAMES["${#BATS_TEST_NAMES[@]}"]=test_Write_key_to_primary
++ bats_test_function test_Read_key_from_slaves
++ local test_name=test_Read_key_from_slaves
++ BATS_TEST_NAMES["${#BATS_TEST_NAMES[@]}"]=test_Read_key_from_slaves
+ '[' -n '' ']'
+ bats_perform_tests test_Testing_mongodb_client_is_executable test_Connect_mongodb_client_to_mongodb_pods test_Write_key_to_primary test_Read_key_from_slaves
+ echo 1..4
+ test_number=1
+ status=0
1..4
+ for test_name in "$@"
+ /tools/bats/bats-exec-test /tests/mongodb-up-test.sh test_Testing_mongodb_client_is_executable 1
+

从日志中可以看到，成功解析到了4个@test代码块, 然后最后循环调用/tools/bats/bats-exec-test, 来看看这个函数

传递了三个参数，第一个是脚本文件，第二个是获取到的@test代码块的名字， 第三个是序号

到/tools/bats/bats-exec-test,调用这个函数

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bats_perform_test() {
  BATS_TEST_NAME="$1"
  if [ "$(type -t "$BATS_TEST_NAME" || true)" = "function" ]; then
    BATS_TEST_NUMBER="$2"
    if [ -z "$BATS_TEST_NUMBER" ]; then
      echo "1..1"
      BATS_TEST_NUMBER="1"
    fi

    BATS_TEST_COMPLETED=""
    BATS_TEARDOWN_COMPLETED=""
    trap "bats_debug_trap \"\$BASH_SOURCE\"" debug  # trap是bash中用于捕捉信号函数
    trap "bats_error_trap" err
    trap "bats_teardown_trap" exit
    "$BATS_TEST_NAME" >>"$BATS_OUT" 2>&1 # 执行命令
    BATS_TEST_COMPLETED=1

  else
    echo "bats: unknown test name \`$BATS_TEST_NAME'" >&2
    exit 1
  fi
}

因此，当命令在执行过程出现error时则会被trap捕获到,然后设置错误码

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bats_error_trap() {
  BATS_ERROR_STATUS="$?"
  BATS_ERROR_STACK_TRACE=( "${BATS_PREVIOUS_STACK_TRACE[@]}" )
  trap - debug
}

这样，一旦生成了错误码，则pod的状态即会出现异常状态，而正常情况下指定了restart:Never的pod执行完启动命令的状态会变成complete.

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# kubectl get pod -n infra
NAME                                 READY   STATUS      RESTARTS   AGE
mongodb-rs-mongodb-replicaset-0      1/1     Running     0          4h36m
mongodb-rs-mongodb-replicaset-1      1/1     Running     0          4h35m
mongodb-rs-mongodb-replicaset-2      1/1     Running     0          4h35m
mongodb-rs-mongodb-replicaset-test   0/1     Completed   0          4h22m

bats还有一些其它的使用技巧, 比如可以使用skip来跳过某些@test代码块、可以用于@test网页等.可到github查看

不过batsN久没有更新了, 有一个改良版的bats-core，是在bats的基本之上改良的，感兴趣的可以看看.

参考文章:

转载请注明原作者: 周淑科(https://izsk.me)

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