Analyzer CLI: Allow commit hashes for comparisons (#33356)

tools/code-analyzer/src/git.ts

@@ -10,7 +10,7 @@ import { readFileSync } from 'fs';
 /**
  * Internal dependencies
  */
-import { startWPEnv, stopWPEnv } from './utils';
+import { startWPEnv, stopWPEnv, isValidCommitHash } from './utils';
 
 /**
  * Fetch branches from origin.
@@ -35,13 +35,20 @@ export const fetchBranch = (
 		return true;
 	}
 
+	if ( isValidCommitHash( branch ) ) {
+		// The hash is valid and available in history. No need to fetch anything.
+		return true;
+	}
+
 	try {
 		// Fetch branch.
 		execSync( `git fetch origin ${ branch }` );
 		// Create branch.
 		execSync( `git branch ${ branch } origin/${ branch }` );
 	} catch ( e ) {
-		error( `Unable to fetch ${ branch }` );
+		error(
+			`Unable to fetch ${ branch }. Supply a valid branch name or commit hash.`
+		);
 		return false;
 	}
 

tools/code-analyzer/src/utils.ts

@@ -174,3 +174,22 @@ export const stopWPEnv = ( error: ( s: string ) => void ): boolean => {
 		return false;
 	}
 };
+
+/**
+ * Check if branch string is actually a commit hash and exists in git history.
+ *
+ * @param {string } branch branch name or commit hash.
+ * @return {boolean} If string is valid commit hash.
+ */
+export const isValidCommitHash = ( branch: string ): boolean => {
+	try {
+		// See if hash is valid and exists in the history.
+		execSync( `git show -s ${ branch }`, {
+			encoding: 'utf-8',
+		} );
+		return true;
+	} catch ( e ) {
+		// git show -s produces an error if the string is not a valid hash.
+		return false;
+	}
+};