[Fix] Infinite while loop when called on root folder, add tests

src/functions/getFirstExistingParentPath.ts

@@ -8,15 +8,31 @@ import Dependencies from '@/src/types/dependencies'
  * @param dependencies - Dependencies container
  */
 async function getFirstExistingParentPath(directoryPath: string, dependencies: Dependencies): Promise<string> {
-	let parentDirectoryPath = directoryPath
+	let parentDirectoryPath = dependencies.pathNormalize(directoryPath)
 	let parentDirectoryFound = await isDirectoryExisting(parentDirectoryPath, dependencies)
 
-	while (!parentDirectoryFound) {
-		parentDirectoryPath = dependencies.pathNormalize(parentDirectoryPath + '/..')
+	const FAILED_TO_FIND_EXISTING_DIRECTORY_VALUE = ''
+
+	/**
+	 * Linux max file path length is 4096 characters.
+	 * With / separators and 1 letter folder names, this gives us a max of ~2048 folders to traverse.
+	 * This is much less error prone than a while loop.
+	 */
+	const maxNumberOfFolders = 2048
+	for (let i = 0; i < maxNumberOfFolders && !parentDirectoryFound; ++i) {
+		const newParentDirectoryPath = dependencies.pathNormalize(parentDirectoryPath + '/..')
+		if (parentDirectoryPath === newParentDirectoryPath || parentDirectoryPath === '.') {
+			return FAILED_TO_FIND_EXISTING_DIRECTORY_VALUE
+		}
+		parentDirectoryPath = newParentDirectoryPath
 		parentDirectoryFound = await isDirectoryExisting(parentDirectoryPath, dependencies)
 	}
 
-	return parentDirectoryPath
+	if (parentDirectoryPath !== '.') {
+		return parentDirectoryPath
+	}
+
+	return FAILED_TO_FIND_EXISTING_DIRECTORY_VALUE
 }
 
 export default getFirstExistingParentPath

test/functions/getFirstExistingParentPath.spec.ts

@@ -4,21 +4,47 @@ import { PathLike } from 'fs'
 import getFirstExistingParentPath from '@/src/functions/getFirstExistingParentPath'
 import mockDependencies from '@/test/__helpers__/mockDependencies'
 
+const getDependencies = (parentPath: string) => mockDependencies({
+	fsAccess: async (directoryPath: PathLike) => directoryPath === parentPath ? Promise.resolve() : Promise.reject(new Error('File does not exists')),
+})
 
 test('unix: get first existing parent path', async t => {
 	const parentPath = '/home/Alex'
-	const dependencies = mockDependencies({
-		fsAccess: async (directoryPath: PathLike) => directoryPath === parentPath ? Promise.resolve() : Promise.reject(new Error('File does not exists')),
-	})
+	const dependencies = getDependencies(parentPath)
 
 	t.is(await getFirstExistingParentPath('/home/Alex/games/Some/Game', dependencies), parentPath)
 })
 
 test('unix: get first parent can be the path itself', async t => {
 	const parentPath = '/home/Alex'
-	const dependencies = mockDependencies({
-		fsAccess: async (directoryPath: PathLike) => directoryPath === parentPath ? Promise.resolve() : Promise.reject(new Error('File does not exists')),
-	})
+	const dependencies = getDependencies(parentPath)
+
+	t.is(await getFirstExistingParentPath(parentPath, dependencies), parentPath)
+})
+
+test('unix: get first parent of root is root', async t => {
+	const parentPath = '/'
+	const dependencies = getDependencies(parentPath)
+
+	t.is(await getFirstExistingParentPath(parentPath, dependencies), parentPath)
+})
+
+test('win32: Gets parent to C:\\Alex', async t => {
+	// note that 'C:/' will fail on UNIX os's as normalize(C:/Alex/..) = C: not C:/
+	const parentPath = 'C:'
+	const dependencies = getDependencies(parentPath)
+	t.is(await getFirstExistingParentPath('C:/Alex', dependencies), parentPath)
+})
 
+test('win32: Returns root folder when called on root folder', async t => {
+	const parentPath = 'C:/'
+	const dependencies = getDependencies(parentPath)
 	t.is(await getFirstExistingParentPath(parentPath, dependencies), parentPath)
 })
+
+test('win32: returns empty string when drive does not exist', async t => {
+	const drivePathThatExists = 'C:/'
+	const dependencies = getDependencies(drivePathThatExists)
+	const drivePathThatDoesNotExist = 'Z:/'
+	t.is(await getFirstExistingParentPath(drivePathThatDoesNotExist, dependencies), '')
+})