feat: Add :if and :optional

.formatter.exs

@@ -1,4 +1,5 @@
 # Used by "mix format"
 [
-  inputs: ["{mix,.formatter}.exs", "{config,lib,test}/**/*.{ex,exs}"]
+  inputs: ["{mix,.formatter}.exs", "{config,lib,test}/**/*.{ex,exs}"],
+  plugins: [Styler]
 ]

.mash.exs

@@ -7,26 +7,29 @@ defmodule MashConfig do
     [
       %{
         name: :restore_cache,
+        if: fn _jobs ->
+          System.get_env("CI")
+        end,
         run: restore_cache()
       },
       %{
         name: :compile_dev,
-        needs: [:restore_cache],
+        needs: [restore_cache: :optional],
         run: mix("do", ["deps.compile,", "compile"], env: [{"MIX_ENV", "dev"}])
       },
       %{
         name: :test,
-        needs: [:restore_cache],
+        needs: [restore_cache: :optional],
         run: mix("test")
       },
       %{
         name: :credo,
-        needs: [:restore_cache],
+        needs: [restore_cache: :optional],
         run: mix("credo", ["--all"])
       },
       %{
         name: :save_cache,
-        needs: [:restore_cache],
+        needs: [:test, :compile_dev],
         run: save_cache()
       },
       %{
@@ -34,6 +37,12 @@ defmodule MashConfig do
         run: fn _io_pid ->
           IO.puts("This line should be captured.")
         end
+      },
+      %{
+        if: false,
+        run: fn _io_pid ->
+          {:error, "This job should not run."}
+        end
       }
     ]
   end

README.md

@@ -60,6 +60,8 @@ Each entry in the jobs list must, at a minimum, have two keys:
 
 Optionally, a job may also contain a key `needs` whose value is an array of other jobs that must pass before this job will be run.
 
+See [the docs for Mash.Job](https://hexdocs.pm/mash/Mash.Job.html) for more details, including conditional execution.
+
 ## Running
 
 ```shell

lib/mash/config.ex

@@ -9,7 +9,7 @@ defmodule Mash.Config do
 
   @callback jobs() :: [%{name: atom(), run: function()}]
 
-  def start_link() do
+  def start_link do
     case Agent.start_link(&compile_config_module!/0, name: __MODULE__) do
       {:error, {:already_started, pid}} ->
         {:ok, pid}

lib/mash/helpers.ex

@@ -75,9 +75,7 @@ defmodule Mash.Helpers do
       if File.exists?(path) do
         cmd("tar", ["-xzf", "#{name}.tar.gz", "--atime-preserve"], io_pid, [])
       else
-        IO.puts(
+        IO.puts(IO.ANSI.yellow() <> "Warning: cache file #{path} does not exist." <> IO.ANSI.reset())
-          IO.ANSI.yellow() <> "Warning: cache file #{path} does not exist." <> IO.ANSI.reset()
-        )
       end
     end
   end

lib/mash/job.ex

@@ -1,9 +1,22 @@
 defmodule Mash.Job do
   @moduledoc """
   Structure that represents the configuration and status of one Mash job.
+
+  Keys:
+  - `:name`: an atom which is the name of the job. It should be unique in the job list.
+  - `:if`: either a function w/ arity 1 or a plain value. The job will be run if the value is truthy \
+          or the function returns true. Otherwise it will be skipped. The argument to an if function is the runner's \
+          job list.
+  - `:needs`: a list of job name atoms which are required before running this job. If a dependency fails or is skipped, \
+             this job will be skipped. You can also include {job_name, :optional} to indicate an optional dependency. \
+             Optional dependencies do not block a job from running if they are skipped, only if they fail.
+  - `:run`: a function with arity 1 that is the code to be executed for the job. See `Mash.Helpers` for shortcut functions.\
+           The argument to the run function is the PID of the IO device which is capturing the output of this job. You\
+           probably don't need this, but you might need it for certain libaries that need to be passed an explicit IO PID.
+  - `:env`: an array of {string, string} pairs which represent ENV variables (name first, then value).
   """
 
-  defstruct name: nil, needs: [], run: nil, env: [], state: nil, task: nil, io_pid: nil
+  defstruct name: nil, if: true, needs: [], run: nil, env: [], state: nil, task: nil, io_pid: nil
 
   def from_map(map) do
     struct(__MODULE__, map)
@@ -11,11 +24,13 @@ defmodule Mash.Job do
 
   def validate(%__MODULE__{run: run, name: name} = job) do
     errors =
-      [
+      Enum.reject(
-        if(!is_function(run, 1), do: "run is required and must be a function with arity 1"),
+        [
-        if(!is_atom(name), do: "name is required and must be an atom")
+          if(!is_function(run, 1), do: "run is required and must be a function with arity 1"),
-      ]
+          if(!is_atom(name), do: "name is required and must be an atom")
-      |> Enum.reject(&is_nil(&1))
+        ],
+        &is_nil(&1)
+      )
 
     if errors == [] do
       {:ok, job}

lib/mash/runner.ex

@@ -22,7 +22,7 @@ defmodule Mash.Runner do
 
     tick()
 
-    jobs = Mash.Config.jobs() |> Enum.map(&Map.put(&1, :state, :to_run))
+    jobs = Enum.map(Mash.Config.jobs(), &Map.put(&1, :state, :to_run))
 
     {:ok, {parent, jobs}}
   end
@@ -34,7 +34,7 @@ defmodule Mash.Runner do
     if any_running?(new_jobs) do
       tick()
     else
-      send(parent, {:result, Enum.count(jobs, &(&1.state == :failed))})
+      send(parent, {:result, Enum.filter(jobs, &(&1.state == :failed))})
       Process.exit(self(), :normal)
     end
 
@@ -44,6 +44,9 @@ defmodule Mash.Runner do
   @spec tick_job(%{state: job_state()}, [Mash.Job.t()]) :: Mash.Job.t()
   def tick_job(%{state: :to_run} = job, jobs) do
     cond do
+      !if?(job, jobs) ->
+        %{job | state: :skipped}
+
       ready?(job, jobs) ->
         %{job | state: :running}
 
@@ -56,15 +59,14 @@ defmodule Mash.Runner do
   end
 
   def tick_job(%{name: name, state: :running, task: nil} = job, _jobs) do
-    IO.puts("Running #{name}")
+    IO.puts("[runner] Running #{name}")
 
     {task, io_pid} = Mash.Execution.run(job)
 
     %{job | task: task, io_pid: io_pid}
   end
 
-  def tick_job(%{name: name, state: :running, task: task, io_pid: io_pid} = job, _jobs)
+  def tick_job(%{name: name, state: :running, task: task, io_pid: io_pid} = job, _jobs) when is_struct(task, Task) do
-      when is_struct(task, Task) do
     flush_io(name, io_pid)
 
     job
@@ -72,6 +74,9 @@ defmodule Mash.Runner do
 
   def tick_job(%{state: state} = job, _jobs) when state in [:passed, :failed, :skipped], do: job
 
+  def if?(%{if: if_fun}, jobs) when is_function(if_fun), do: !!if_fun.(jobs)
+  def if?(%{if: if_val}, _jobs), do: !!if_val
+
   def any_running?(jobs) do
     Enum.any?(jobs, &(&1.state == :running))
   end
@@ -93,18 +98,29 @@ defmodule Mash.Runner do
   end
 
   defp ready?(%{needs: needs}, jobs) do
-    Enum.all?(needs, fn needed_job_name ->
+    Enum.all?(needs, fn
-      needed_job = Enum.find(jobs, &(&1.name == needed_job_name))
+      {needed_job_name, :optional} ->
+        needed_job = Enum.find(jobs, &(&1.name == needed_job_name))
 
-      needed_job.state == :passed
+        needed_job.state in [:skipped, :passed]
+
+      needed_job_name ->
+        needed_job = Enum.find(jobs, &(&1.name == needed_job_name))
+
+        needed_job.state == :passed
     end)
   end
 
   defp skippable?(%{needs: needs}, jobs) do
-    Enum.any?(needs, fn needed_job_name ->
+    Enum.any?(needs, fn
-      needed_job = Enum.find(jobs, &(&1.name == needed_job_name))
+      {needed_job_name, :optional} ->
+        needed_job = Enum.find(jobs, &(&1.name == needed_job_name))
+        needed_job.state == :failed
 
-      needed_job.state in [:failed, :skipped]
+      needed_job_name ->
+        needed_job = Enum.find(jobs, &(&1.name == needed_job_name))
+
+        needed_job.state in [:failed, :skipped]
     end)
   end
 
@@ -120,7 +136,7 @@ defmodule Mash.Runner do
 
     StringIO.close(job.io_pid)
     new_state = interpret_result(result)
-    IO.puts("Finishing #{job_name} -- #{new_state}")
+    IO.puts("[runner] Finishing #{job_name} -- #{new_state}")
 
     new_job = %{
       job

lib/mix/tasks/mash.ex

@@ -1,20 +1,22 @@
 defmodule Mix.Tasks.Mash do
+  @shortdoc "Run Mash jobs."
+
   @moduledoc """
   Task to run Mash jobs.
   """
-  @shortdoc "Run Mash jobs."
-
   use Mix.Task
 
   def run(_args) do
     {:ok, _pid} = Mash.Runner.start_link()
 
     receive do
-      {:result, failure_count} when failure_count > 0 ->
+      {:result, []} ->
-        Mix.raise("#{failure_count} job(s) failed.", exit_status: 1)
-
-      {:result, 0} ->
         :ok
+
+      {:result, failures} ->
+        failure_list = Enum.map_join(failures, "\n", fn %{name: name} -> "- #{name}" end)
+        failure_count = Enum.count(failures)
+        Mix.raise("#{failure_count} job(s) failed.\n#{failure_list}", exit_status: 1)
     end
   end
 end

mix.exs

@@ -4,7 +4,7 @@ defmodule Mash.MixProject do
   def project do
     [
       app: :mash,
-      version: "0.1.2",
+      version: "0.2.0",
       elixir: "~> 1.14",
       start_permanent: Mix.env() == :prod,
       deps: deps(),
@@ -31,7 +31,8 @@ defmodule Mash.MixProject do
   defp deps do
     [
       {:ex_doc, "~> 0.30.4", only: :dev},
-      {:credo, "~> 1.7"}
+      {:credo, "~> 1.7"},
+      {:styler, "~> 0.8.4"}
       # {:dep_from_hexpm, "~> 0.3.0"},
       # {:dep_from_git, git: "https://github.com/elixir-lang/my_dep.git", tag: "0.1.0"}
     ]

mix.lock

@@ -9,4 +9,5 @@
   "makeup_elixir": {:hex, :makeup_elixir, "0.16.1", "cc9e3ca312f1cfeccc572b37a09980287e243648108384b97ff2b76e505c3555", [:mix], [{:makeup, "~> 1.0", [hex: :makeup, repo: "hexpm", optional: false]}, {:nimble_parsec, "~> 1.2.3 or ~> 1.3", [hex: :nimble_parsec, repo: "hexpm", optional: false]}], "hexpm", "e127a341ad1b209bd80f7bd1620a15693a9908ed780c3b763bccf7d200c767c6"},
   "makeup_erlang": {:hex, :makeup_erlang, "0.1.2", "ad87296a092a46e03b7e9b0be7631ddcf64c790fa68a9ef5323b6cbb36affc72", [:mix], [{:makeup, "~> 1.0", [hex: :makeup, repo: "hexpm", optional: false]}], "hexpm", "f3f5a1ca93ce6e092d92b6d9c049bcda58a3b617a8d888f8e7231c85630e8108"},
   "nimble_parsec": {:hex, :nimble_parsec, "1.3.1", "2c54013ecf170e249e9291ed0a62e5832f70a476c61da16f6aac6dca0189f2af", [:mix], [], "hexpm", "2682e3c0b2eb58d90c6375fc0cc30bc7be06f365bf72608804fb9cffa5e1b167"},
+  "styler": {:hex, :styler, "0.8.4", "70580b48e728c81e0ad02f9de26839da35281547fb2369e397d84eb7840ec6d8", [:mix], [], "hexpm", "4525686e49d1784a53c0964f1602c33250caf7646c14a0e1c7dddca806337428"},
 }

test/mash_test.exs

@@ -1,4 +1,5 @@
 defmodule MashTest do
   use ExUnit.Case
+
   doctest Mash
 end