legendary-doc-site/script/coverage-json-to-cobertura

#!/usr/bin/env elixir

Mix.install([
  {:jason, "~> 1.0"},
  {:xml_builder, "~> 2.1"}
])

%{"source_files" => data} =
  "cover/excoveralls.json"
  |> File.read!()
  |> Jason.decode!()

{total_covered, total_total} =
  data
  |> Enum.reduce({0,0}, fn %{"coverage" => cover}, {covered, total} ->
    file_covered =
      cover
      |> Enum.reduce(0, &(if is_integer(&1) && &1 > 0, do: &2 + 1, else: &2))

    file_total =
      cover
      |> Enum.reduce(0, &(if is_nil(&1), do: &2, else: &2 + 1))

    {covered + file_covered, total + file_total}
  end)

ratio = total_covered / total_total

files =
  data
  |> Enum.map(fn %{"coverage" => cover, "name" => name} ->
    file_covered =
      cover
      |> Enum.reduce(0, &(if is_integer(&1) && &1 > 0, do: &2 + 1, else: &2))

    file_total =
      cover
      |> Enum.reduce(0, &(if is_nil(&1), do: &2, else: &2 + 1))

    lines =
      cover
      |> Enum.with_index
      |> Enum.map(fn
        {nil, _index} ->
          nil
        {line, index} ->
          {:line, %{"number" => index, "hits" => line}, []}
      end)
      |> Enum.reject(&is_nil/1)

    ratio =
      if file_total == 0 do
        1.0
      else
        file_covered / file_total
      end

    {
      :class,
      %{"filename" => name, "line-rate" => ratio},
      [
        {
          :lines,
          %{},
          lines
        }
      ]
    }
  end)

source =
  if System.get_env("CI_PROJECT_NAME") do
    "#{System.get_env("CI_BUILDS_DIR")}/#{System.get_env("CI_PROJECT_NAMESPACE")}/#{System.get_env("CI_PROJECT_NAME")}"
  else
    File.cwd!
  end


buffer =
  XmlBuilder.document([
    XmlBuilder.doctype(
      "coverage",
      system: ["http://cobertura.sourceforge.net/xml/coverage-03.dtd"]
    ),
    {
      :coverage,
      %{
        "line-rate" => ratio,
      },
      [
        {
          :sources,
          %{},
          [
            {
              :source,
              %{},
              source
            }
          ]
        },
        {
          :packages,
          %{},
          [
            {
              :package,
              %{"name" => "", "line-rate" => ratio},
              [
                {
                  :classes,
                  %{},
                  files
                }
              ]
            }
          ]
        }
      ]
    }
  ])
  |> XmlBuilder.generate

File.write!("cover/cobertura.xml", buffer)