feat: Enhance GetGitDiffCommand class in git diff command file

The GetGitDiffCommand class has been updated to improve its functionality. Now, an instance of the SimpleGit class is created during the construction phase and used later for obtaining git diffs. Furthermore, a new private method isBlank has been added to check if the diff result is empty. This leads to cleaner and more maintainable code.

src/commands/get-git-diff/GetGitDiffCommand.ts

@@ -9,19 +9,21 @@ export type GitDiffError = Error;
 
 export class GetGitDiffCommand implements Command<GitDiffResult> {
     private readonly gitDiffOptions = ['--staged'];
+    private readonly git: SimpleGit;
 
-    public constructor(private readonly repositoryPath: string) {}
+    public constructor(private readonly repositoryPath: string) {
+        this.git = simpleGit(this.repositoryPath).clean(CleanOptions.FORCE);
+    }
 
     public async execute(): Promise<Result<GitDiffResult, GitDiffError>> {
         eventBroker.emit('git-diff-started-event', this.gitDiffOptions);
 
-        const git: SimpleGit = simpleGit(this.repositoryPath).clean(CleanOptions.FORCE);
         try {
             const now = Date.now();
-            const diff = await git.diff(this.gitDiffOptions);
+            const diff = await this.git.diff(this.gitDiffOptions);
             const duration = Date.now() - now;
 
-            if (!z.string().min(1).safeParse(diff).success) {
+            if (this.isBlank(diff)) {
                 eventBroker.emit('git-diff-empty-event');
 
                 return Err(new Error('The git diff is empty.'));
@@ -38,4 +40,8 @@ export class GetGitDiffCommand implements Command<GitDiffResult> {
             return error;
         }
     }
+
+    private isBlank(str: string): boolean {
+        return !z.string().min(1).safeParse(str).success;
+    }
 }