improvement: Enable git_ops.check_message to check the latest commit message.

lib/mix/tasks/git_ops.check_message.ex

@@ -4,9 +4,15 @@ defmodule Mix.Tasks.GitOps.CheckMessage do
   @shortdoc "Check if a file's content follows the Conventional Commits spec"
 
   @moduledoc """
-  Receives a file path and validates if it's content follows the Conventional Commits specification.
+  Validates a commit message against the Conventional Commits specification.
+
+  Check a file containing a commit message using:
 
       mix git_ops.check_message <path/to/file>
+
+  or to check the most recent commit on the current branch:
+
+      mix git_ops.check_message --head
 
   Logs an error if the commit message is not parse-able.
 
@@ -17,6 +23,15 @@ defmodule Mix.Tasks.GitOps.CheckMessage do
   alias GitOps.Config
 
   @doc false
+  def run(["--head"]) do
+    message =
+      Config.repository_path()
+      |> Git.init!()
+      |> Git.log!(["-1", "--format=%s"])
+
+    validate(message)
+  end
+
   def run([path]) do
     # Full paths do not need to be wrapped with repo root
     path =
@@ -26,8 +41,17 @@ defmodule Mix.Tasks.GitOps.CheckMessage do
         Path.join(Config.repository_path(), path)
       end
 
-    message = File.read!(path)
+    path
+    |> File.read!()
+    |> validate()
+  end
+
+  def run(_), do: error_exit("Invalid usage. See `mix help git_ops.check_message`")
 
+  @spec error_exit(String.t()) :: no_return
+  defp error_exit(message), do: raise(Mix.Error, message: message)
+
+  defp validate(message) do
     case Commit.parse(message) do
       {:ok, _} ->
         :ok
@@ -70,9 +94,4 @@ defmodule Mix.Tasks.GitOps.CheckMessage do
         """)
     end
   end
-
-  def run(_), do: error_exit("Invalid usage. See `mix help git_ops.check_message`")
-
-  @spec error_exit(String.t()) :: no_return
-  defp error_exit(message), do: raise(Mix.Error, message: message)
 end

test/check_message_test.exs

@@ -2,7 +2,7 @@
 Mix.shell(Mix.Shell.Process)
 
 defmodule GitOps.Mix.Tasks.Test.CheckMessageTest do
-  use ExUnit.Case
+  use ExUnit.Case, async: false
 
   alias Mix.Tasks.GitOps.CheckMessage
 
@@ -17,6 +17,46 @@ defmodule GitOps.Mix.Tasks.Test.CheckMessageTest do
       CheckMessage.run(["path/to/nowhere"])
     end
   end
+
+  describe "with --head" do
+    setup do
+      repo_path = System.tmp_dir!()
+        |> Path.join("repo")
+
+      repo = Git.init!(repo_path)
+
+      Application.put_env(:git_ops, :repository_path, repo_path)
+
+      on_exit(fn ->
+        Application.delete_env(:git_ops, :repository_path)
+        File.rm_rf!(repo_path)
+
+        :ok
+      end)
+
+      {:ok, repo: repo}
+    end
+
+    test "it fails when the repo contains no commits" do
+      assert_raise(Git.Error, ~r/does not have any commits/, fn ->
+        CheckMessage.run(["--head"])
+      end)
+    end
+
+    test "it fails when the latest commit does not have a valid message", %{repo: repo} do
+      Git.commit!(repo, ["-m 'invalid message'", "--allow-empty"])
+
+      assert_raise(Mix.Error, ~r/Not a valid Conventional Commit message/, fn ->
+        CheckMessage.run(["--head"])
+      end)
+    end
+
+    test "it succeeds when the latest commit has a valid message", %{repo: repo} do
+      Git.commit!(repo, ["-m 'chore: counting toes'", "--allow-empty"])
+
+      assert :ok = CheckMessage.run(["--head"])
+    end
+  end
 
   describe "with valid path" do
     setup do

test/config_test.exs

@@ -10,7 +10,7 @@ defmodule GitOps.Test.ConfigTest do
     Application.put_env(:git_ops, :changelog_file, "CUSTOM_CHANGELOG.md")
     Application.put_env(:git_ops, :manage_readme_version, true)
     Application.put_env(:git_ops, :types, custom: [header: "Custom"], docs: [hidden?: false])
-    Application.put_env(:git_ops, :tags, [allowed: ["tag_1", "tag_2"], allow_untagged?: false])
+    Application.put_env(:git_ops, :tags, allowed: ["tag_1", "tag_2"], allow_untagged?: false)
     Application.put_env(:git_ops, :version_tag_prefix, "v")
   end