parse empty commits

__test__/entrypoint.sh

@@ -22,6 +22,7 @@ git config --global user.name "Your Name"
 echo "#test-base" > README.md
 git add .
 git commit -m "initial commit"
+git commit --allow-empty -m "empty commit for tests"
 echo "#test-base :sparkles:" > README.md
 git add .
 git commit -m "add sparkles" -m "Change description:

__test__/git-command-manager.int.test.ts

@@ -11,17 +11,26 @@ describe('git-command-manager integration tests', () => {
   })
 
   it('tests getCommit', async () => {
-    const parent = await git.getCommit('HEAD^')
-    const commit = await git.getCommit('HEAD')
-    expect(parent.subject).toEqual('initial commit')
-    expect(parent.signed).toBeFalsy()
-    expect(parent.changes).toEqual([
+    const initialCommit = await git.getCommit('HEAD^^')
+    const emptyCommit = await git.getCommit('HEAD^')
+    const headCommit = await git.getCommit('HEAD')
+
+    expect(initialCommit.subject).toEqual('initial commit')
+    expect(initialCommit.signed).toBeFalsy()
+    expect(initialCommit.changes).toEqual([
       {mode: '100644', status: 'A', path: 'README.md'}
     ])
-    expect(commit.subject).toEqual('add sparkles')
-    expect(commit.parents[0]).toEqual(parent.sha)
-    expect(commit.signed).toBeFalsy()
-    expect(commit.changes).toEqual([
+
+    expect(emptyCommit.subject).toEqual('empty commit for tests')
+    expect(emptyCommit.tree).toEqual(initialCommit.tree) // empty commits have no tree and reference the parent's
+    expect(emptyCommit.parents[0]).toEqual(initialCommit.sha)
+    expect(emptyCommit.signed).toBeFalsy()
+    expect(emptyCommit.changes).toEqual([])
+
+    expect(headCommit.subject).toEqual('add sparkles')
+    expect(headCommit.parents[0]).toEqual(emptyCommit.sha)
+    expect(headCommit.signed).toBeFalsy()
+    expect(headCommit.changes).toEqual([
       {mode: '100644', status: 'M', path: 'README.md'}
     ])
   })