GitDirectoryResource: Accept "/", "", "." as root paths (#1860)

GitDirectoryResource was merged in
#1858.
Unfortunately, it didn't provide an easy way of saying "checkout all the
files from the repo". This PR adds support for three root path syntaxes:

* `"path": "/"`
* `"path": "."`
* `"path": ""`

 ## Testing instructions

Run this Blueprint locally and confirm it installs the blocky formats
plugin:

```json
{
	"$schema": "https://playground.wordpress.net/blueprint-schema.json",
	"login": true,
	"landingPage": "/wp-admin/",
    "steps": [
        {
            "step": "installPlugin",
            "pluginData": {
                "resource": "git:directory",
                "url": "https://github.com/dmsnell/blocky-formats.git",
                "ref": "trunk",
                "path": "/"
            }
        }
    ]
}
```

packages/playground/blueprints/src/lib/resources.ts

@@ -461,9 +461,13 @@ export class GitDirectoryResource extends Resource<Directory> {
 		const repoUrl = this.options?.corsProxy
 			? `${this.options.corsProxy}/${this.reference.url}`
 			: this.reference.url;
-		const ref = `refs/heads/${this.reference.ref}`;
+		const ref = ['', 'HEAD'].includes(this.reference.ref)
+			? 'HEAD'
+			: `refs/heads/${this.reference.ref}`;
 		const allFiles = await listGitFiles(repoUrl, ref);
-		const filesToClone = listDescendantFiles(allFiles, this.reference.path);
+
+		const requestedPath = this.reference.path.replace(/^\/+/, '');
+		const filesToClone = listDescendantFiles(allFiles, requestedPath);
 		let files = await sparseCheckout(repoUrl, ref, filesToClone);
 		// Remove the path prefix from the cloned file names.
 		files = Object.fromEntries(

packages/playground/storage/src/lib/paths.spec.ts

@@ -0,0 +1,122 @@
+import { FileTree } from './git-sparse-checkout';
+import { listDescendantFiles } from './paths';
+
+const testTree: FileTree[] = [
+	{
+		name: 'packages',
+		type: 'folder',
+		children: [
+			{
+				name: 'playground',
+				type: 'folder',
+				children: [
+					{
+						name: 'storage',
+						type: 'folder',
+						children: [
+							{
+								name: 'package.json',
+								type: 'file',
+							},
+							{
+								name: 'STORAGE_README.md',
+								type: 'file',
+							},
+						],
+					},
+				],
+			},
+			{
+				name: 'php-wasm',
+				type: 'folder',
+				children: [
+					{
+						name: 'package.json',
+						type: 'file',
+					},
+				],
+			},
+		],
+	},
+	{
+		name: 'wordpress',
+		type: 'folder',
+		children: [
+			{
+				name: 'wp-content',
+				type: 'folder',
+				children: [
+					{
+						name: 'plugins',
+						type: 'folder',
+						children: [
+							{
+								name: 'blocky-formats',
+								type: 'folder',
+								children: [
+									{
+										name: 'block.json',
+										type: 'file',
+									},
+									{
+										name: 'index.php',
+										type: 'file',
+									},
+									{
+										name: 'README.md',
+										type: 'file',
+									},
+								],
+							},
+						],
+					},
+				],
+			},
+			{
+				name: 'index.php',
+				type: 'file',
+			},
+			{
+				name: 'wp-includes',
+				type: 'folder',
+				children: [
+					{
+						name: 'version.php',
+						type: 'file',
+					},
+				],
+			},
+			{
+				name: 'wp-config.php',
+				type: 'file',
+			},
+		],
+	},
+];
+
+describe('listDescendantFiles', () => {
+	it('should list all the descendant files from a subdirectory of a file tree', async () => {
+		const files = listDescendantFiles(testTree, 'packages/playground');
+		expect(files).toEqual(
+			expect.arrayContaining([
+				'packages/playground/storage/package.json',
+				'packages/playground/storage/STORAGE_README.md',
+			])
+		);
+	});
+	it.each(['.', '/', ''])(
+		'should list all the descendant files when "%s" is passed as path',
+		async (path: string) => {
+			const files = listDescendantFiles(
+				[
+					{
+						name: 'index.php',
+						type: 'file',
+					},
+				],
+				path
+			);
+			expect(files).toEqual(expect.arrayContaining(['index.php']));
+		}
+	);
+});

packages/playground/storage/src/lib/paths.ts

@@ -1,41 +1,46 @@
+import { normalizePath } from '@php-wasm/util';
 import { FileTree } from './git-sparse-checkout';
 
 export function listDescendantFiles(files: FileTree[], selectedPath: string) {
-	if (!selectedPath) {
-		return [];
-	}
+	selectedPath = normalizePath(selectedPath);
+	const isRoot = ['', '.', '/'].includes(selectedPath);
 
-	// Calculate the list of files to checkout based on the mapping
-	const descendants: string[] = [];
-	const segments = selectedPath.split('/');
 	let currentTree: FileTree[] | null = files;
-	for (const segment of segments) {
-		const file = currentTree?.find(
-			(file) => file.name === segment
-		) as FileTree;
-		if (file?.type === 'folder') {
-			currentTree = file.children;
-		} else if (file) {
-			return [file.name];
-		} else {
-			return [];
+	if (isRoot) {
+		selectedPath = '';
+	} else {
+		const segments = selectedPath.split('/');
+		for (const segment of segments) {
+			const file = currentTree?.find(
+				(file) => file.name === segment
+			) as FileTree;
+			if (file?.type === 'folder') {
+				currentTree = file.children;
+			} else if (file) {
+				return [file.name];
+			} else {
+				return [];
+			}
 		}
 	}
 
+	// Calculate the list of files to checkout based on the mapping
+	const descendants: string[] = [];
 	const stack = [{ tree: currentTree, path: selectedPath }];
 	while (stack.length > 0) {
 		const { tree, path } = stack.pop() as {
 			tree: FileTree[];
 			path: string;
 		};
 		for (const file of tree) {
+			const filePath = `${path}${path ? '/' : ''}${file.name}`;
 			if (file.type === 'folder') {
 				stack.push({
 					tree: file.children,
-					path: `${path}/${file.name}`,
+					path: filePath,
 				});
 			} else {
-				descendants.push(`${path}/${file.name}`);
+				descendants.push(filePath);
 			}
 		}
 	}