count_spec.rb

require 'aws-sdk'

class MetricsWriter

  def initialize(connection_info)
    @client = Aws::DynamoDB::Client.new(connection_info)
    ensure_tables
  end

  def ensure_tables
    @client.create_table({
                             table_name: 'metrics',
                             attribute_definitions: [
                                 {
                                     attribute_name: 'org',
                                     attribute_type: 'S'
                                 },
                                 {
                                     attribute_name: 'unit',
                                     attribute_type: 'S'
                                 }
                             ],
                             key_schema: [
                                 {
                                     attribute_name: 'org',
                                     key_type: 'HASH'
                                 },
                                 {
                                     attribute_name: 'unit',
                                     key_type: 'range'
                                 }
                             ],
                             provisioned_throughput: {
                                 read_capacity_units: 1,
                                 write_capacity_units: 1
                             }
                         })
  end

  def save(records)
    records.each do |record|
      @client.put_item({
                           'table_name': 'metrics',
                           item: record
                       })
    end
  end

end

RSpec.describe MetricsWriter do

  connection_info = {region: 'us-east-1', endpoint: 'http://localhost:8000'}
  dynamodb = Aws::DynamoDB::Client.new(connection_info)

  before(:each) do
    tables = dynamodb.list_tables.table_names
    if tables.include?('metrics')
      dynamodb.delete_table({
                                table_name: 'metrics',
                            })
    end
  end

  it 'saves metering records' do
    metrics_records = [
        {
            'org': 'my-org-1',
            'unit': 'ops',
            'at': '2016-02-28T11:21:33+05:30',
            'data': [{'id': 'p1', 'result': 'pass'}, {'id': 'p2', 'result': 'fail'}]
        },
        {
            'org': 'my-org-1',
            'unit': 'dev',
            'at': '2016-02-29T12:22:33+05:30',
            'data': [{'id': 'p1', 'result': 'pass'}, {'id': 'p2', 'result': 'fail'}]
        },
        {
            'org': 'my-org-2',
            'unit': 'fin',
            'at': '2016-02-29T13:23:33+05:30',
            'data': [{'id': 'p1', 'result': 'pass'}, {'id': 'p2', 'result': 'fail'}]
        }
    ]

    MetricsWriter.new(connection_info).save(metrics_records)

    response = dynamodb.query({
                                  table_name: 'metrics',
                                  select: 'COUNT',
                                  key_condition_expression: "org = :v_org",
                                  expression_attribute_values: {
                                      ":v_org": 'my-org-1',
                                  },
                                  return_consumed_capacity: 'TOTAL'
                              })

    expect(response.count).to eql(2)
  end

end