add test

packages/rspack/tests/configCases/resolve/roots/dir/a.js

@@ -0,0 +1 @@
+export default 'a'

packages/rspack/tests/configCases/resolve/roots/dir2/b.js

@@ -0,0 +1 @@
+export default "b"

packages/rspack/tests/configCases/resolve/roots/index.js

@@ -0,0 +1,8 @@
+import a from "/dir/a";
+
+it("should support roots", async () => {
+  expect(a).toBe("a");
+  const b = "b"; // keep /dir2/ as a context module
+  const m = await import("/dir2/" + b);
+  expect(m.default).toBe("b")
+})

packages/rspack/tests/configCases/resolve/roots/webpack.config.js

@@ -0,0 +1,3 @@
+module.exports = {
+  context: __dirname,
+}