Set rootMode: "root" in loadPartialConfig (#13040)

packages/babel-core/src/config/partial.js

@@ -139,6 +139,7 @@ export default function* loadPrivatePartialConfig(
     envName: context.envName,
     cwd: context.cwd,
     root: context.root,
+    rootMode: "root",
     filename:
       typeof context.filename === "string" ? context.filename : undefined,
 

packages/babel-core/test/config-chain.js

@@ -982,6 +982,7 @@ describe("buildConfigChain", function () {
       browserslistConfigFile: false,
       cwd: process.cwd(),
       root: process.cwd(),
+      rootMode: "root",
       envName: "development",
       passPerPreset: false,
       plugins: [],

packages/babel-core/test/config-loading.js

@@ -118,6 +118,25 @@ describe("@babel/core config loading", () => {
       expect(item.value).toBe(preset);
       expect(item.options).toBe(false);
     });
+
+    it("should always set 'rootMode' to 'root'", async () => {
+      const cwd = path.join(
+        path.dirname(fileURLToPath(import.meta.url)),
+        "fixtures",
+        "config-loading",
+        "root",
+        "nested",
+      );
+
+      const { options } = await loadPartialConfig({
+        cwd,
+        filename: path.join(cwd, "file.js"),
+        rootMode: "upward",
+      });
+
+      expect(options.root).toBe(path.join(cwd, ".."));
+      expect(options.rootMode).toBe("root");
+    });
   });
 
   describe("config file", () => {

packages/babel-core/test/fixtures/config-loading/root/babel.config.json

@@ -0,0 +1 @@
+{}