RSpec测试JSON API遇Webpacker文件缺失错误，求解决方案

背景 #

我创建了一个工时表（timesheet），想用JSON API测试其CRUD功能，但运行RSpec测试时，控制台返回Webpacker无法找到文件的错误。

测试代码（创建工时表的RSpec代码） #

it 'Create timesheet' do
    timesheet = {
        start_date: Date.new(2023,1,1), 
        end_date: Date.new(2023,1,31)
    }
    sign_in_as_a_valid_user
    post "/timesheets.json", headers: headers, params: timesheet, as: :json
    expect(response).to have_http_status(:created)
    json_response = JSON.parse(response.body)
    byebug
    expect(json_response['start_date']).to eq(2023,1,1)
    expect(json_response['end_date']).to eq(2023,1,31)
end

错误信息 #

运行测试后控制台返回的错误：

1) Api Create timesheet
     Failure/Error: <%= javascript_pack_tag 'application', 'data-turbolinks-track': 'reload', defer: true %>
     
     ActionView::Template::Error:
       Webpacker can't find application.js in /home/yir/Documents/workspace/projet1/alpha/public/packs-test/manifest.json. Possible causes:
       1. You want to set webpacker.yml value of compile to true for your environment
          unless you are using the `webpack -w` or the webpack-dev-server.
       2. webpack has not yet re-run to reflect updates.
       3. You have misconfigured Webpacker's config/webpacker.yml file.
       4. Your webpack configuration is not creating a manifest.
       Your manifest contains:
       {
       }

补充（2023年4月18日）：工时表控制器代码 #

class TimesheetsController < ApplicationController
  before_action :set_timesheet, only: %i[ show edit update destroy ]
  before_action :authenticate_user!
  # GET /timesheets or /timesheets.json
  def index
    @timesheets = Timesheet.order(start_date: :asc)
  end

  # GET /timesheets/1 or /timesheets/1.json
  def show
  end

  # GET /timesheets/new
  def new
    @timesheet = Timesheet.new
    my_date = Date.today
    @days = my_date.beginning_of_month.upto(my_date.end_of_month)
  end

  # GET /timesheets/1/edit
  def edit
  end

  # POST /timesheets or /timesheets.json
  def create

    @timesheet = Timesheet.new(timesheet_params)

    respond_to do |format|
      if @timesheet.save
        format.html { redirect_to @timesheet, notice: "Timesheet was successfully created." }
        format.json { render :show, status: :created, location: @timesheet }
      else
        format.html { render :new, status: :unprocessable_entity }
        format.json { render json: @timesheet.errors, status: :unprocessable_entity }
      end
    end
  end

  # PATCH/PUT /timesheets/1 or /timesheets/1.json
  def update
    respond_to do |format|
      if @timesheet.update(timesheet_params)
        format.html { redirect_to @timesheet, notice: "Timesheet was successfully updated." }
        format.json { render :show, status: :ok, location: @timesheet }
      else
        format.html { render :edit, status: :unprocessable_entity }
        format.json { render json: @timesheet.errors, status: :unprocessable_entity }
      end
    end
  end

  # DELETE /timesheets/1 or /timesheets/1.json
  def destroy
    @timesheet.destroy
    respond_to do |format|
      format.html { redirect_to timesheets_url, notice: "Timesheet was successfully destroyed." }
      format.json { head :no_content }
    end
  end

  private
    # Use callbacks to share common setup or constraints between actions.
    def set_timesheet
      @timesheet = Timesheet.find(params[:id])
    end

    # Only allow a list of trusted parameters through.
    def timesheet_params
      params.require(:timesheet).permit(:month, :start_date, :end_date)
    end
end

解决方案 #

1. 配置测试环境自动编译Webpack资源 #

打开config/webpacker.yml，找到test环境配置，将compile设置为true：

test:
  <<: *default
  compile: true
  # 其他配置保持不变

这样测试时Webpack会自动编译缺失的资源，无需手动运行编译命令。

2. 手动编译测试环境的Webpack资源 #

在项目根目录执行以下命令，提前编译测试环境的前端资源：

RAILS_ENV=test bundle exec rails webpacker:compile

执行完成后再重新运行RSpec测试。

3. 修复测试参数并避免渲染HTML模板 #

从错误信息看，测试过程中触发了HTML模板渲染，核心原因有两个：

• 测试参数未按控制器要求包裹在:timesheet键下，导致参数校验失败，控制器走了format.html分支渲染模板。修改测试参数为：

timesheet = {
    timesheet: {
        start_date: Date.new(2023,1,1), 
        end_date: Date.new(2023,1,31)
    }
}

• 检查sign_in_as_a_valid_user方法，确保它仅设置认证会话（比如直接赋值session[:user_id] = valid_user.id），而非渲染HTML页面或跳转。

4. 简化测试环境的布局配置（可选） #

如果API测试完全不需要前端资源，可以修改控制器，在测试环境下关闭API动作的布局：

class TimesheetsController < ApplicationController
  # ...其他代码
  layout false, only: [:create, :update, :destroy, :index, :show] if Rails.env.test?
  # ...其他代码
end

这样测试时API动作不会渲染包含Webpack标签的布局。

内容的提问来源于stack exchange，提问作者yir