refactor: migrate getLastCommitSha to use the Git Extension

src/git/wrapped_repository.ts

@@ -87,6 +87,10 @@ export class WrappedRepository {
     return this.getRemoteByName(pipelineGitRemoteName || this.remoteName);
   }
 
+  get lastCommitSha(): string | undefined {
+    return this.rawRepository.state.HEAD?.commit;
+  }
+
   get instanceUrl(): string {
     const remoteUrls = this.rawRepository.state.remotes
       .map(r => r.fetchUrl)

src/git_service.test.ts

@@ -59,17 +59,6 @@ describe('git_service', () => {
       gitService = new GitService(getDefaultOptions());
     });
 
-    describe('fetchLastCommitId', () => {
-      it('returns the last commit sha', async () => {
-        await git.commit('Test commit', [], { '--allow-empty': null });
-        const lastCommitSha = await git.revparse(['HEAD']);
-
-        const result = await gitService.fetchLastCommitId();
-
-        expect(result).toEqual(lastCommitSha);
-      });
-    });
-
     describe('fetchTrackingBranchName', () => {
       beforeEach(async () => {
         await git.checkout(['-b', 'new-branch']);
@@ -138,10 +127,6 @@ describe('git_service', () => {
       gitService = new GitService(options);
     });
 
-    it('fetchLastCommitId returns null', async () => {
-      expect(gitService.fetchLastCommitId()).rejects.toBeInstanceOf(Error);
-    });
-
     it('fetchTrackingBranchName returns null', async () => {
       expect(gitService.fetchTrackingBranchName()).rejects.toBeInstanceOf(Error);
     });

src/git_service.ts

@@ -27,10 +27,6 @@ export class GitService {
     return stdout;
   }
 
-  async fetchLastCommitId(): Promise<string> {
-    return this.fetch('git log --format=%H -n 1');
-  }
-
   /**
    * Fetches remote tracking branch name of current branch.
    * This should be used in link openers.

src/openers.ts

@@ -140,9 +140,8 @@ export async function compareCurrentBranch(): Promise<void> {
   if (!repository) return;
 
   const project = await gitLabService.fetchCurrentProject(repository.rootFsPath);
-  const lastCommitId = await repository.gitService.fetchLastCommitId();
 
-  if (project && lastCommitId) {
-    openUrl(`${project.webUrl}/compare/master...${lastCommitId}`);
+  if (project && repository.lastCommitSha) {
+    openUrl(`${project.webUrl}/compare/master...${repository.lastCommitSha}`);
   }
 }