Commit.from_object/1: Add tests for interop with command-line git.

test/xgit/core/commit_test.exs

@@ -7,9 +7,13 @@ defmodule Xgit.Core.CommitTest do
   alias Xgit.GitInitTestCase
   alias Xgit.Repository
   alias Xgit.Repository.OnDisk
+  alias Xgit.Test.OnDiskRepoTestCase
 
   import FolderDiff
 
+  import Xgit.Test.OnDiskRepoTestCase,
+    only: [setup_with_valid_tree!: 0, setup_with_valid_parent_commit!: 0]
+
   @valid_pi %PersonIdent{
     name: "A. U. Thor",
     email: "author@example.com",
@@ -24,6 +28,8 @@ defmodule Xgit.Core.CommitTest do
     tz_offset: 150
   }
 
+  @env OnDiskRepoTestCase.sample_commit_env()
+
   describe "valid?/1" do
     test "valid: no parent" do
       assert Commit.valid?(%Commit{
@@ -214,8 +220,69 @@ defmodule Xgit.Core.CommitTest do
   end
 
   describe "from_object/1" do
-    # TO DO: Test ability to read commits generated by command-line git.
-    # https://github.com/elixir-git/xgit/issues/203
+    test "command-line interop: no parents" do
+      %{xgit_path: path, xgit_repo: repo, tree_id: tree_id} = setup_with_valid_tree!()
+
+      assert {commit_id_str, 0} =
+               System.cmd("git", ["commit-tree", tree_id, "-m", "xxx"], cd: path, env: @env)
+
+      commit_id = String.trim(commit_id_str)
+
+      {:ok, commit_object} = Repository.get_object(repo, commit_id)
+
+      assert {:ok,
+              %Xgit.Core.Commit{
+                author: %Xgit.Core.PersonIdent{
+                  email: "author@example.com",
+                  name: "A. U. Thor",
+                  tz_offset: 150,
+                  when: 1_142_878_449
+                },
+                committer: %Xgit.Core.PersonIdent{
+                  email: "author@example.com",
+                  name: "A. U. Thor",
+                  tz_offset: 150,
+                  when: 1_142_878_449
+                },
+                message: 'xxx\n',
+                parents: [],
+                tree: "3e69f02f3247843b482cc99872683692999f6703"
+              }} = Commit.from_object(commit_object)
+    end
+
+    test "command-line interop: one parent" do
+      %{xgit_path: path, xgit_repo: repo, tree_id: tree_id, parent_id: parent_id} =
+        setup_with_valid_parent_commit!()
+
+      assert {commit_id_str, 0} =
+               System.cmd("git", ["commit-tree", tree_id, "-m", "mumble", "-p", parent_id],
+                 cd: path,
+                 env: @env
+               )
+
+      commit_id = String.trim(commit_id_str)
+
+      {:ok, commit_object} = Repository.get_object(repo, commit_id)
+
+      assert {:ok,
+              %Xgit.Core.Commit{
+                author: %Xgit.Core.PersonIdent{
+                  email: "author@example.com",
+                  name: "A. U. Thor",
+                  tz_offset: 150,
+                  when: 1_142_878_449
+                },
+                committer: %Xgit.Core.PersonIdent{
+                  email: "author@example.com",
+                  name: "A. U. Thor",
+                  tz_offset: 150,
+                  when: 1_142_878_449
+                },
+                message: 'mumble\n',
+                parents: [^parent_id],
+                tree: "3e69f02f3247843b482cc99872683692999f6703"
+              }} = Commit.from_object(commit_object)
+    end
 
     test "valid: no parent" do
       assert {:ok,