backend-test-utils: add MockDirectory content callback + default file modes

Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>

packages/backend-test-utils/api-report.md

@@ -54,9 +54,24 @@ export interface MockDirectory {
 
 // @public
 export type MockDirectoryContent = {
-  [name in string]: MockDirectoryContent | string | Buffer;
+  [name in string]:
+    | MockDirectoryContent
+    | string
+    | Buffer
+    | MockDirectoryContentCallback;
 };
 
+// @public
+export type MockDirectoryContentCallback = (
+  ctx: MockDirectoryContentCallbackContext,
+) => void;
+
+// @public
+export interface MockDirectoryContentCallbackContext {
+  path: string;
+  symlink(target: string): void;
+}
+
 // @public
 export interface MockDirectoryContentOptions {
   path?: string;

packages/backend-test-utils/src/filesystem/MockDirectory.test.ts

@@ -119,6 +119,20 @@ describe('createMockDirectory', () => {
     });
   });
 
+  it('should be able to use callback for more detailed file system operations', () => {
+    mockDir.setContent({
+      'a.txt': 'a',
+      'b.txt': ctx => ctx.symlink('./a.txt'),
+      'c.txt': ctx => fs.copyFileSync(mockDir.resolve('a.txt'), ctx.path),
+    });
+
+    expect(mockDir.content()).toEqual({
+      'a.txt': 'a',
+      'b.txt': 'a',
+      'c.txt': 'a',
+    });
+  });
+
   it('should read content from sub dirs', () => {
     mockDir.setContent({
       'a.txt': 'a',

packages/backend-test-utils/src/filesystem/MockDirectory.ts

@@ -30,6 +30,28 @@ import {
 
 const tmpdirMarker = Symbol('os-tmpdir-mock');
 
+/**
+ * A context that allows for more advanced file system operations when writing mock directory content.
+ *
+ * @public
+ */
+export interface MockDirectoryContentCallbackContext {
+  /** Absolute path to the location of this piece of content on the filesystem */
+  path: string;
+
+  /** Creates a symbolic link at the current location */
+  symlink(target: string): void;
+}
+
+/**
+ * A callback that allows for more advanced file system operations when writing mock directory content.
+ *
+ * @public
+ */
+export type MockDirectoryContentCallback = (
+  ctx: MockDirectoryContentCallbackContext,
+) => void;
+
 /**
  * The content of a mock directory represented by a nested object structure.
  *
@@ -54,7 +76,11 @@ const tmpdirMarker = Symbol('os-tmpdir-mock');
  * @public
  */
 export type MockDirectoryContent = {
-  [name in string]: MockDirectoryContent | string | Buffer;
+  [name in string]:
+    | MockDirectoryContent
+    | string
+    | Buffer
+    | MockDirectoryContentCallback;
 };
 
 /**
@@ -178,6 +204,11 @@ type MockEntry =
   | {
       type: 'dir';
       path: string;
+    }
+  | {
+      type: 'callback';
+      path: string;
+      callback: MockDirectoryContentCallback;
     };
 
 /** @internal */
@@ -214,10 +245,18 @@ class MockDirectoryImpl {
       }
 
       if (entry.type === 'dir') {
-        fs.ensureDirSync(fullPath, { mode: 0o777 });
+        fs.ensureDirSync(fullPath);
       } else if (entry.type === 'file') {
-        fs.ensureDirSync(dirname(fullPath), { mode: 0o777 });
-        fs.writeFileSync(fullPath, entry.content, { mode: 0o666 });
+        fs.ensureDirSync(dirname(fullPath));
+        fs.writeFileSync(fullPath, entry.content);
+      } else if (entry.type === 'callback') {
+        fs.ensureDirSync(dirname(fullPath));
+        entry.callback({
+          path: fullPath,
+          symlink(target: string) {
+            fs.symlinkSync(target, fullPath);
+          },
+        });
       }
     }
   }
@@ -287,6 +326,8 @@ class MockDirectoryImpl {
         });
       } else if (node instanceof Buffer) {
         entries.push({ type: 'file', path, content: node });
+      } else if (typeof node === 'function') {
+        entries.push({ type: 'callback', path, callback: node });
       } else {
         entries.push({ type: 'dir', path });
         for (const [name, child] of Object.entries(node)) {

packages/backend-test-utils/src/filesystem/index.ts

@@ -20,4 +20,6 @@ export {
   type MockDirectoryOptions,
   type MockDirectoryContent,
   type MockDirectoryContentOptions,
+  type MockDirectoryContentCallback,
+  type MockDirectoryContentCallbackContext,
 } from './MockDirectory';