Fix gitignore paths applying as root-relative

Changed code to ensure that the folder hierarchy is included in all gitignore entries.

Should fix #36.

changelog.md

@@ -1,5 +1,8 @@
 # Changelog
 
+## Next
+- Fixed gitignore paths being applied as root-relative ([#36](https://github.com/Nixinova/LinguistJS/issues/36)).
+
 ## 2.8.0
 *2024-09-15*
 - Added checking of gitattributes override rule `linguist-detectable`.

src/helpers/walk-tree.ts

@@ -54,7 +54,13 @@ export default function walk(data: WalkInput): WalkOutput {
 		if (FS.existsSync(gitignoreFilename)) {
 			const gitignoreContents = FS.readFileSync(gitignoreFilename, 'utf-8');
 			const ignoredPaths = parseGitignore(gitignoreContents);
-			ignored.add(ignoredPaths);
+			const rootRelIgnoredPaths = ignoredPaths.map(ignorePath =>
+				// get absolute path of the ignore glob
+				normPath(folder, ignorePath)
+					// convert abs ignore glob to be relative to the root folder
+					.replace(commonRoot + '/', '')
+			);
+			ignored.add(rootRelIgnoredPaths);
 		}
 
 		// Add gitattributes if present

test/samples/.gitignore

@@ -1,2 +1,2 @@
 # Ignore this file
-ignore*
+.gitignore