dofs: treat empty find pattern as no pattern

find compiled the pattern argument into a regex whenever it was not
undefined. An empty string is defined, so find(db, dir, "") produced
the regex ^$, which matches only empty relative paths and returned no
results instead of every entry.

Guard the compile step on a truthy pattern so an empty string behaves
like an omitted pattern and walks the whole tree. Add a regression test
covering the empty-pattern case.

Author: aron-cf

packages/dofs/src/fs/find.test.ts

@@ -27,6 +27,21 @@ describe("find", () => {
     });
   });
 
+  it("treats an empty pattern like no pattern and returns every entry", async () => {
+    await withDB(async (db) => {
+      mkdir(db, "/a/b", { recursive: true }, () => 0);
+      await writeFile(db, "/a/x.ts", "", {}, () => 0);
+      await writeFile(db, "/a/b/y.md", "", {}, () => 0);
+      const entries = find(db, "/", "").sort((p, q) => p.path.localeCompare(q.path));
+      expect(entries).toEqual([
+        { path: "/a", type: "dir" },
+        { path: "/a/b", type: "dir" },
+        { path: "/a/b/y.md", type: "file" },
+        { path: "/a/x.ts", type: "file" },
+      ]);
+    });
+  });
+
   it("matches a single-level glob *.ts within the directory only", async () => {
     await withDB(async (db) => {
       mkdir(db, "/a/b", { recursive: true }, () => 0);

packages/dofs/src/fs/find.ts

@@ -25,7 +25,10 @@ export function find(db: Database, directory: string, pattern?: string): Workspa
   }
 
   const out: WorkspaceFoundEntry[] = [];
-  const regex = pattern !== undefined ? compileGlob(pattern) : undefined;
+  // An empty pattern is equivalent to no pattern: walk and return
+  // everything rather than compiling it into `^$`, which would match
+  // only empty relative paths and yield no results.
+  const regex = pattern ? compileGlob(pattern) : undefined;
 
   walk(db, node.inode, canonical, out);